JP2019090995A - Optical system, imaging device, distance measuring device, and on-vehicle camera system - Google Patents

Abstract

A compact, low-cost optical system capable of distance measurement is provided. An optical system (L0) for forming an image of an object, comprising first and second imaging optical systems (L1, L2) and light from each of the first and second imaging optical systems The first and second images formed by the first and second imaging optical systems, which have first and second aperture stops (SP) arranged on the path, are oriented in the direction of the Ys axis. and the paths of the reference rays passing through the centers of the apertures of the first and second aperture stops and reaching the center of the reduction surface on the XsYs plane are defined as the first and second reference axes, When the first and second extension axes obtained by extending the first and second reference axes from the reduction surface in the traveling direction of the reference ray are projected onto the YsZs plane, the first and second extension axes are cross each other. [Selection drawing] Fig. 1

Description

  The present invention relates to a wide-angle optical system capable of distance measurement.

  A wide-angle lens applied to surveillance cameras, in-vehicle cameras, UAVs (Unmanned Aerial Vehicles), etc., while securing a wide field of view, in a compact, low-priced two-group configuration in which the number of lenses is reduced The type of lens is known. In Patent Document 1, a biconcave lens with negative refractive power, an aperture stop, and a biconvex lens with positive refractive power, which are arranged in order from the object side, form at least one surface of the biconcave lens or biconvex lens as an aspheric surface. Wide-angle lenses are known.

  Patent Document 2 and Patent Document 3 disclose a design method of the non-coaxial optical system and a calculation method of paraxial amount such as focal length. An optical system in which the aberration is sufficiently corrected by introducing the concept of a reference axis as in Patent Document 2 and Patent Document 3 and making the constituent surface of the optical system asymmetrical with respect to the reference axis and aspheric, It has become clear that it can be built.

  Such non-coaxial optics are called off-axial (off-axial) optics. The off-axial optical system is a curved surface (off-axial curved surface) in which the surface normal at the point of intersection with the reference axis of the component surface is not on the reference axis Defined as an optical system including In this case, the reference axis has a bent shape. In the Off-Axial optical system, the constituent surface is generally non-coaxial, and vignetting does not occur even on the reflective surface, so it is easy to construct an optical system using the reflective surface. Further, by forming an intermediate image in the optical system, a compact optical system can be configured while realizing a wide angle of view. In addition, although it is an optical system of the front stop, the optical path can be relatively freely routed, so it is possible to construct a compact optical system.

  Patent Document 4 discloses a method of calculating an object distance from a stereo image.

Unexamined-Japanese-Patent No. 9-159912 gazette JP-A-9-5650 JP 2005-24695 A JP-A-8-14861

  By the way, with regard to on-vehicle cameras and UAVs, since there are severe restrictions on the size and weight of the imaging device to be mounted, downsizing and thinning of the optical system are desired. There is no problem with conventional optical systems as long as images are simply acquired. However, when trying to measure the distance from the image and use it for sensing to control the own vehicle (or own vehicle) using the result, it is possible to widen the angle while reducing aberrations that are different for each image height such as distortion. You need to In addition, high-speed image processing is also required. When an optical system is configured with a refractive lens as disclosed in Patent Document 1, it is difficult to achieve both widening of the angle and distortion reduction. I will.

  Although the optical system which uses a free-form surface mirror is disclosed by patent document 2 and patent document 3, there is no mention for utilizing for sensing which measures distance. For example, even if it is necessary to use two imaging elements even if it is going to comprise a stereo optical system using two optical systems of patent document 2 and patent document 3, the scale of a signal processing calculation will become large. In addition, if a dedicated imaging device or circuit for reducing the scale of signal processing operation is prepared, the cost increases. Patent Document 4 discloses a method of calculating a subject distance from a stereo image, but does not mention an optical configuration that is optimal when configuring a stereo optical system.

  Therefore, an object of the present invention is to provide an optical system, an imaging device, a distance measuring device, and an on-vehicle camera system that can perform distance measurement in a small size and at low cost.

  An optical system according to one aspect of the present invention is an optical system that forms an image of an object, and includes light of first and second imaging optical systems and respective light of the first and second imaging optical systems. An intermediate point of a straight line connecting the aperture centers of the first and second aperture stops is an origin point, and the first and second aperture stops are arranged from the aperture center of the first aperture stop. The straight line whose direction toward the opening center of the second aperture stop is positive is the Ys axis, and the straight line perpendicular to the Ys axis passes the origin according to the definition of the right-handed coordinate system, the Xs axis passes the origin, the Xs axis and the Xs axis When a straight line perpendicular to each of the Ys axes is taken as a Zs axis, first and second images formed by each of the first and second imaging optical systems are along the direction of the Ys axis. Arrayed, passing through the centers of the respective first and second apertures and X The path of the reference ray reaching the center of the reduction plane on the Ys plane is taken as the first and second reference axes, and the first and second reference axes are extended from the reduction plane in the traveling direction of the reference ray When the obtained first and second extension axes are projected onto the YsZs plane, the first and second extension axes intersect with each other.

  An imaging device as another aspect of the present invention includes the optical system and an imaging element that receives an image formed by the optical system.

  A distance measuring apparatus according to another aspect of the present invention includes the imaging device for acquiring image data of an object, and a distance calculating unit for acquiring distance information to the object based on the image data.

  An on-vehicle camera system according to another aspect of the present invention includes the distance measuring device, and a collision determination unit that determines the possibility of collision between the host vehicle and the object based on the distance information.

  Other objects and features of the present invention will be described in the following embodiments.

  According to the present invention, it is possible to provide a compact, low-cost optical system capable of distance measurement, an imaging device, a distance measuring device, and an on-vehicle camera system.

1 is a cross-sectional view of an optical system and a schematic layout view of an imaging device in a first embodiment. It is a figure which shows the distortion of the optical system in 1st Embodiment. FIG. 5 is a lateral aberration diagram of the optical system in the first embodiment. They are a sectional view of an optical system in a 2nd embodiment, and a schematic layout of an imaging device. It is a figure which shows the distortion of the optical system in 2nd Embodiment. It is a transverse aberration figure of the optical system in a 2nd embodiment. They are a sectional view of an optical system in a 3rd embodiment, and a schematic layout of an imaging device. It is a figure which shows the distortion of the optical system in 3rd Embodiment. It is a transverse-aberration figure of the optical system in 3rd Embodiment. It is explanatory drawing of the coordinate system in each embodiment. It is explanatory drawing of the coordinate system in each embodiment. It is explanatory drawing of the evaluation position of the horizontal aberration in each embodiment. It is an arrangement | positioning figure of the last image formation surface on the image pick-up element in each embodiment. It is an arrangement | positioning figure of the last image formation surface on the image pick-up element in each embodiment. It is a figure which shows the relationship between the coordinate system of the stereo optical system in each embodiment, and the absolute coordinate system of each imaging optical system. It is a figure which shows the relationship between the stereo optical system and each imaging optical system in each embodiment. It is a functional block diagram of the in-vehicle camera system in a 4th embodiment. It is the principal part schematic of the vehicle in 4th Embodiment. It is a flowchart which shows the operation example of the vehicle-mounted camera system in 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, matters common to each embodiment will be described together with the outline of the present invention.

(Items common to each embodiment)
1) Definition of Optical Coordinate System, etc. FIG. 10 is an explanatory view of a coordinate system which defines configuration data of an imaging optical system used for the optical system (stereo optical system) of each embodiment. In each embodiment, from the center of the object surface (not shown) to the center of the pupil (aperture: aperture stop SP) from the object side (the object side) to the image side (the image forming surface formed on the imaging device) One ray passing through the center) to the center of the image plane is defined as a central chief ray or a reference axis ray. The object side may be referred to as a magnifying conjugate side, and the image side may be referred to as a reduction conjugate side. In FIG. 10, the central chief ray or the reference axis ray is indicated by an alternate long and short dash line. Also, the path followed by the central chief ray or the reference axis ray is defined as a reference axis. Further, along the reference axis, the i-th surface from the object side is the i-th surface Ri.

  In FIG. 10, the first surface R1 is an aperture stop SP (diaphragm surface) disposed on the light path, the second surface R2 is a reflective surface tilted with respect to the first surface R1, the third surface R3 and the fourth surface R4 are Reflective surfaces shifted and tilted with respect to each previous surface. Each of the reflecting surfaces from the second surface R2 to the fourth surface R4 is a mirror made of a medium such as metal, glass, or plastic. In addition, it does not limit to 4th surface R4, and a reflective surface may continue on 5th surface R5 or subsequent ones.

  Since the imaging optical system in the stereo optical system of each embodiment is an off-axial optical system (off axial optical system), the surfaces constituting the imaging optical system do not have a common optical axis. So, in each embodiment, the absolute coordinate system which makes the origin the center of 1st surface R1 is set. That is, the path followed by the ray (central chief ray or reference axis ray) passing through the origin position of the imaging optical coordinate system that is the center of the first surface R1 and the center position of the optical final imaging surface (reduction surface) is It is a reference axis. Also, the reference axis has a direction. The direction is the direction in which the central chief ray or the reference axis ray travels during imaging. Here, the “final image forming surface” is an image forming surface which exists at the end of the light path of the image forming optical system, and is also simply referred to as “image forming surface” or “image surface”. Imaging is performed by disposing the imaging element IMG0 on the final imaging plane. The final imaging plane is an optical plane and does not directly mean an imaging device. Therefore, "the center of the final image forming surface" does not mean "the center of the imaging element IMG0". Therefore, "the center of the final image forming plane" is not limited to "the center of the imaging element IMG0". As described later, when there is an imaging surface connecting a real image in the middle of the light path, the imaging surface is called an “intermediate imaging surface”. The term "imaging plane" or "image plane" simply refers to the final imaging plane.

  In each of the following embodiments, each refracting surface until the central chief ray or the reference axis ray passes through the center point (origin) of the first surface R1 which is the aperture center of the aperture stop SP to the center of the final image forming surface And refract and reflect by reflective surfaces. The order of the constituent surfaces is set in the order in which the central chief ray or the reference axis ray is incident from the object side (enlarged conjugate side) to be refracted and reflected. For this reason, the reference axis finally reaches the center of the final image plane while changing its direction according to the law of refraction or reflection along the order of each set surface. Moreover, in each of the following embodiments, the object side (enlargement conjugate side) and the image side (reduction conjugate side) mean which side with respect to the direction of the reference axis.

  In each embodiment, the reference axis which is the reference of the imaging optical system is set as described above, but the method of determining the axis is an optical design, an aberration summary, or each constituting the imaging optical system. A convenient axis may be employed to express the surface shape. In general, if the path taken by the ray passing through the center of the image plane and either the stop, the entrance pupil, the exit pupil, or the center of the first surface R1 of the imaging optical system or the final surface is set as the reference axis Good.

  In each of the following embodiments, each axis of the absolute coordinate system of the imaging optical system is determined as follows. That is, the Z-axis is a straight line passing through the origin and the center of the object plane (a reference axis passing from the object side to the center (opening center) of the aperture stop SP (first surface R1)), from the object plane to the first surface R1. The direction is positive. The Y-axis is a straight line passing through the origin and at 90 ° counterclockwise to the Z-axis according to the definition of the right-handed coordinate system. The X-axis is a straight line passing through the origin and perpendicular to each of the Z-axis and the Y-axis, and the direction toward the back of the paper surface of FIG. 10 is positive.

  Further, the surface shape and tilt angle of the ith surface constituting the optical system can be easily understood by expressing as follows. Set a local coordinate system whose origin is the point where the reference axis and the i-th plane intersect. Then, the surface shape of the surface may be represented in the local coordinate system, and the tilt angle may be represented by the angle between the reference axis and the local coordinate system. Therefore, the surface shape of the i-th surface is expressed by the following local coordinate system. That is, the z-axis is the surface normal that passes through the origin of the local coordinates (the positive direction is shown in FIG. 10). The y-axis is a straight line passing through the origin of the local coordinates and making a 90 ° counterclockwise with respect to the z-direction according to the definition of the right-handed coordinate system. The x-axis is a straight line passing through the origin of the local coordinates and perpendicular to the yz-plane, and the direction toward the back of the paper surface of FIG. 10 is positive.

Therefore, the tilt angle in the yz-plane of the i-th surface is an acute angle that the z-axis of the local coordinate system makes with the reference axis, and is represented by an angle θ _xi (unit “°”) with the counterclockwise direction being positive. Be done. Further, the tilt angle in the xz plane of the i-th plane is expressed by an angle θ _yi (unit “°”) with the positive counterclockwise direction with respect to the reference axis. Further, the tilt angle in the xy plane of the i-th plane is expressed by an angle θ _zi (unit “°”) with the positive counterclockwise direction with respect to the y axis. However, normally, the angle θ _zi corresponds to the rotation of the surface, and does not exist in the following embodiments. FIG. 10 shows the correlation between these absolute coordinate systems and the local coordinate system. The directions of the arrows of the respective axes in FIG. 10 indicate the positive and negative directions of the respective axes. (+) Indicates the positive direction, and (-) indicates the negative direction. In FIG. 10, a ray obliquely incident on the absolute coordinate origin is drawn as an off-axis chief ray. When the incident angle of the off-axis principal ray on the YZ plane is ωy, the sign of the incident angle is defined with the on-axis principal ray entering from above as negative and the on-axis chief ray entering from below as a positive angle. Although drawn on the YZ plane in FIG. 10, the sign of the incident angle on the XZ plane is shown in FIG.

  FIG. 11 is a diagram in which the coordinate system depicted in FIG. 10 is rotated 90 degrees clockwise about the Z axis, and the direction from the back of the paper to the front of the Y axis is positive. At this time, assuming that the incident angle of the off-axis chief ray on the XZ plane is ωx with the Z-axis as a reference, the off-axis chief ray incident from above is negative, and the off-axis chief ray incident from below is positive. Define the sign of the incident angle. A light ray located at the outermost side (a position where the incident angle ωx or ωy is the largest angle) of the incident angles ωx and ωy determines the maximum angle of view of the optical system on the XZ plane and the YZ plane, respectively It is.

  So far, the coordinate system for each imaging optical system has been described. However, the coordinate system when a stereo optical system is configured by combining two imaging optical systems is determined as follows. That is, the Zs axis is the center (opening center) SPO1 of the aperture stop (first aperture stop) SP of the imaging optical system L1 and the center (opening center of the aperture stop (second aperture stop) SP of the imaging optical system L2. ) A middle point of a straight line connecting SPO 2 is an origin point O, and the straight line passes through the center of the object plane and the origin. The direction from the object plane center to the origin O is positive. The Ys axis is a straight line that passes through the origin O and forms an angle of 90 ° counterclockwise with respect to the Zs axis according to the definition of the right-handed coordinate system. The Xs axis is a straight line passing through the origin O and perpendicular to each of the Zs axis and the Ys axis. The direction in which the Ys axis makes 90 ° counterclockwise around the Zs axis is positive. In other words, each axis is defined as follows. That is, an intermediate point of a straight line connecting the center SPO1 of the aperture stop SP of the imaging optical system L1 and the center SPO2 of the aperture stop SP of the imaging optical system L2 is set as an origin O. At this time, the Ys axis is a straight line whose direction from the center SPO1 of the aperture stop SP of the imaging optical system L1 to the center SPO2 of the aperture stop SP of the imaging optical system L2 is positive. The Xs axis is a straight line passing through the origin O and perpendicular to the Ys axis according to the definition of the right-handed coordinate system. The Zs axis is a straight line perpendicular to each of the Xs axis and the Ys axis.

  FIG. 15 is a diagram showing the mutual relationship between the coordinate system of the stereo optical system L0 and the absolute coordinate system of the imaging optical systems L1 and L2. In FIG. 15, the directions of the arrows of the respective axes indicate the positive and negative directions of the respective axes. That is, (+) indicates the positive direction, and (-) indicates the negative direction.

2) Specific Expression of Imaging Optical System In each embodiment, numerical data of each constituent surface is shown as a numerical example. Di is a scalar quantity representing the distance between the origin of the local coordinates of the i-th surface and the (i + 1) -th surface, Ndi and didi are the refractive index and Abbe number of the medium between the i-th surface and the (i + 1) -th surface. In each embodiment, the medium between the origins is air. E-X represents a ^{10 -X.} A spherical surface is a shape represented by the following formula (A), where Ri is the radius of curvature of the i-th surface and x and y are local coordinate values of the i-th surface.

  The imaging optical systems of the following embodiments each have two or more surfaces (free-form surfaces) having a rotationally asymmetric shape (curvature), and the shape is represented by the following equation (B).

  The surface equation represented by the equation (B) is only an even order term with respect to x. Therefore, the curved surface defined by the curved surface equation represented by the equation (B) has a plane-symmetrical shape with the yz plane as a plane of symmetry.

3) Ideal form as stereo optical system The stereo optical system in each embodiment (the first and second imaging optical systems for condensing the light flux from the subject on the first and second imaging planes) Based on ideas like Heretofore, there has been a transmission type optical system using a lens in an optical system for use in a car-mounted camera. Then, various optical systems have been proposed which measure the distance by arranging the same two optical systems horizontally and viewing them in stereo, or acquiring a 3D shape. In addition, various optical systems of small size and high image quality have also been proposed using an imaging optical system including a rotationally asymmetric reflective surface. In order to measure a distance with high precision using a stereo optical system or to acquire a 3D shape, it is necessary to enhance imaging performance to achieve high image quality. Moreover, in the distance measurement application by a vehicle-mounted camera, since it is necessary to catch the circumference widely, it is necessary to widen to a certain extent.

  When a stereo optical system is configured by a transmission type lens optical system, it is possible to form a wide-angle high-quality stereo optical system having a bright F value by increasing the number of lenses. However, since the number of parts is greatly increased, the cost is increased, and it is necessary to suppress the manufacturing error and the assembling error, which increases the manufacturing difficulty. On the other hand, when the stereo optical system is configured not by a transmission type lens optical system but by a free-form surface prism optical system having a rotationally asymmetric reflective surface in a prism, a plurality of reflective surfaces can be integrated. Therefore, it is possible to reduce the imaging performance deterioration due to the manufacturing error at the time of assembly. However, in the case of the free-form surface prism, chromatic aberration occurs at the interface with the air on the incident side or the interface at the exit side, and it is difficult to maintain a wide visible light region with high image quality only with the prism. In addition, the transmittance in the prism may differ depending on the wavelength, or even in the environment resistance, the entire optical system may be distorted due to temperature change, and the material constituting the prism is limited. Furthermore, because the entire optical system is a prism, the weight is heavier than it looks.

4) Outline of the present invention (hollow reflection mirror configuration having a rotationally asymmetric shape, and configuration in which a stereo optical system is imaged on one imaging device)
In each embodiment, the imaging optical system constituting the stereo optical system has a hollow reflection mirror configuration (hollow mirror configuration) having a rotationally asymmetric shape (free curved surface shape). As a result, it is not necessary to increase the number of lenses for chromatic aberration correction, and it is possible to maintain a high F value and high imaging performance with a small number of parts. Here, in the hollow mirror configuration, the reflecting surface is a mirror structure in which a material having a high reflectance in the visible light region such as silver or aluminum is vapor-deposited, and both the incident side and the emitting side (reflection side) of the reflecting surface A configuration that is a gaseous medium such as air or vacuum. Thus, each embodiment is not a configuration in which light propagates in a transparent solid such as a prism and is reflected by a wall surface (or a boundary with the outside) in the solid. Use of a prism or the like is not preferable because it causes chromatic aberration as described above.

  Further, in each embodiment, the final image forming surface of the two image forming optical systems constituting the stereo optical system is formed on the surface of one imaging element IMG0. As a result, it is not necessary to prepare two independent signal processing circuits, and image information of the two imaging optical systems can be extracted only by specifying the readout region.

First Embodiment
Next, a first embodiment of the present invention will be described. First, the basic configuration of the stereo optical system (optical system) L0 of the present embodiment will be described with reference to FIG. An imaging optical system (first imaging optical system) including an imaging element IMG0 common to at least two reflecting surface i-th surfaces Ri (i is a surface number sequentially given from the object side) of the stereo optical system L0 ) L1 and an imaging optical system (second imaging optical system) L2. The two imaging optical systems L1 and L2 included in the stereo optical system L0 each have an aperture stop SP (first surface R1) on the most object side. In FIG. 1, the aperture stop SP, the common imaging element IMG0, and the imaging optical systems L1 and L2 are displayed. In addition, regarding the aperture stop SP, in FIG. 1, it is assumed that it is one optical element surface, and the notation R1 is in parentheses. Each of the final imaging planes formed by the two imaging optical systems L1 and L2 of the stereo optical system L0 is formed on one imaging element IMG0.

  FIG. 1 shows the arrangement (YsZs plane) of the imaging optical system inside the stereo optical system L0 in this embodiment. In FIG. 1, light is taken in from each of two aperture stops SP, and passes through the second surface R2 to the sixth surface R6, which are reflection surfaces of the imaging optical system L1 and the imaging optical system L2, to be coupled to the imaging element IMG0. It shows how to make an image. The position of the aperture stop SP corresponds to the position of the entrance pupil of the Off-Axial imaging optical system L1 and the imaging optical system L2 which are composed of the second surface R2 to the sixth surface R6, which are a plurality of reflecting surfaces.

  In FIG. 1, the reflecting surface second surface R2 to the sixth surface R6 constituting the imaging optical systems L1 and L2 each have a rotationally asymmetric shape, and the off-axial optical system in which the reference axis is bent as described above (Off axial optical system) is configured. The imaging element IMG0 is disposed at the position of the final imaging plane formed by the imaging optical systems L1 and L2. FIG. 13 is a layout view of final imaging planes IMG1 and IMG2 on the imaging element IMG0. In FIG. 13, the final imaging surface formed by the imaging optical system L1 is shown as IMG1, and the final imaging surface formed by the imaging optical system L2 is shown as IMG2. As described above, in the present embodiment, two final imaging planes (partial areas) are arranged side by side on the imaging element IMG0 in the horizontal direction (the same direction as the Ys axis). As described above, in the present embodiment, the imaging optical systems L1 and L2 form a plurality of images having parallax with each other in different regions of one imaging element IMG0.

  Since the imaging optical systems L1 and L2 are optical systems having the same design value, data of numerical examples and distortions and lateral aberrations described later are representatively shown by an example of the imaging optical system L2. FIG. 2 shows the state of distortion in the present embodiment (Numerical Example 1). In FIG. 2, the horizontal axis represents coordinate values (corresponding to an X angle of view) on the image plane in the X axis direction, and the vertical axis represents coordinate values (corresponding to a Y angle of view) on the image plane in the Y axis direction. Also, the distortion-free ideal grid (Paraxial FOV) and the grid of actual ray tracing results (Actual FOV) are superimposed and drawn. In the case of an optical system with large distortion, it is easy to see that the gratings are offset, but since the imaging optical systems L1 and L2 of this embodiment can reduce distortion very well, an actual grating is substantially the same as the ideal grating. Indistinguishable.

  FIG. 12 shows evaluation positions 1, 2, 3, 4 and 5 on final imaging planes IMG1 and IMG2 on the imaging element IMG0. FIG. 3 shows transverse aberration diagrams at evaluation positions 1 to 5. Further, in the lateral aberration diagram of FIG. 3, the horizontal axis is taken as the X-axis or Y-axis on the pupil plane, and the vertical axis is meant for the amount of aberration on the image plane. The wavelength of the evaluation beam is d-line. ω is a half angle of view. In all aberration diagrams, when each numerical value example to be described later is expressed in mm, it is drawn on a scale of lateral aberration ± 0.025 mm. In addition, the overlapping description is abbreviate | omitted in each embodiment after this embodiment, and the meaning of the code | symbol used redundantly is made common unless there is a notice.

  Next, based on the configuration of the present embodiment, the features and advantageous effects of the present invention will be described. As described above, various methods for acquiring the distance between a subject and a camera and the distance between subjects using a stereo optical system have been conventionally disclosed. In addition, various techniques have been disclosed in which miniaturization and improvement in imaging performance are compatible by using a reflection optical system utilizing a free curved surface mirror having a rotationally asymmetric shape for an imaging device.

  However, stereo optics require two imaging optics. That is, two imaging elements are needed if it thinks simply. Image information from two imaging elements is acquired, and arithmetic processing is performed on the two image information after imaging. If it is permissible to take time to perform arithmetic processing here, the conventional signal processing apparatus is sufficient. However, in the case where a stereo optical system is mounted on a device such as a UAV and it is intended to autonomously move the device while feeding back the sensing result in real time, it is necessary to have a fast signal processing capability. As a result, equipment such as waste heat measures and securing of the power supply may become large, and it may not be able to be installed in the UAV.

  Therefore, in the present embodiment, as shown in FIG. 1, the two final imaging planes formed by the imaging optical systems L1 and L2 can be formed on one imaging element plane. However, if two imaging optical systems are simply arranged to form an image on one imaging device, a very large imaging device surface is required, or an imaging device having a special shape is required. As a result, it is necessary to make a dedicated imaging device, which is not preferable because the cost is extremely high. Alternatively, when a large imaging element is used, there are many areas not used for imaging, which is not efficient. Therefore, in order to make it possible to use imaging elements conventionally mass-produced, the two final imaging planes are arranged in close proximity. Also, in order to be able to do that, the two final imaging planes are arranged at an angle to one another from the reference axis. As a result, the optical members constituting the two imaging optical systems can be arranged without interference, and the two final imaging planes can be arranged close to each other. For this reason, it is possible to efficiently use one imaging element surface for stereo image acquisition.

  As described above, since the two final imaging planes are configured to be inclined from the reference axis, when the respective reference axes of the imaging optical systems L1 and L2 are further extended in the light ray traveling direction, the respective final imaging plane positions It crosses at the intersection point P on the back side. When the imaging optical systems L1 and L2 can be ideally manufactured and assembled without error, the intersection point P is formed on the YsZs plane as shown in FIG. However, there is actually a manufacturing error, and it is also conceivable that the reference axes of the imaging optical systems L1 and L2 are not on the same YsZs plane. Therefore, two extended reference axes are projected and considered in the YsZs plane. In this way, the two reference axes have an intersection point P which always intersects at one point. That is, in the present embodiment, the first and second images (parallax images) formed by the imaging optical systems L1 and L2 are arranged along the direction of the Ys axis. Here, the final image forming surface (reduction surface) on the Xs Ys plane passes through the opening centers (SPO1 and SPO2) of the first and second aperture stops (the aperture stops SP of the imaging optical systems L1 and L2). The path of the reference beam leading to the center of the first and second reference axes. When the first and second extension axes obtained by extending the first and second reference axes in the direction of travel of the reference beam from the reduction plane are projected onto the YsZs plane, the first and second extension axes are Cross each other at intersection point P.

  The imaging optical systems L1 and L2 of the present embodiment are configured as described above, but preferably are configured to satisfy at least one of the following conditions. According to this, it is possible to obtain a stereo optical system that is compact and capable of distance measurement and can reduce the information processing calculation scale while achieving both widening of angle and reduction of distortion, and an imaging device using the same.

  The imaging optical systems L1 and L2 each have two or more reflecting surfaces (free-form surfaces) having a rotationally asymmetric shape in order to bend the reference axis. By having such a reflective surface, aberration correction can be made easier, and imaging performance can be improved. Preferably, at least one of the reflective surfaces having a rotationally asymmetric shape is decentered in the imaging optical systems L1 and L2. Further, each of the imaging optical systems L1 and L2 has an aperture stop SP on the object side of the reflection surface (first reflection surface) closest to the object side among the plurality of reflection surfaces having a rotationally asymmetric shape. As a result, all of the light rays finally incident on the imaging device can be incident on the imaging device without being disturbed by the edges of the optical elements included in the imaging optical systems L1 and L2, so that peripheral light reduction can be reduced. It becomes possible.

  Further, in each of the imaging optical systems L1 and L2, the aperture stop SP is disposed as the first surface R1 and the position of the aperture stop SP is the entrance pupil position, so that each reflecting surface is obtained even if the angle of view is increased. Also has the advantage of not becoming larger. As a result, the incident light and the reflected light on each of the reflection surfaces can share the same space, so that the space can be effectively used, and downsizing can be achieved. Even when the entrance pupil position does not strictly come to the position of the aperture stop SP due to a manufacturing error or the like, a slight deviation is allowed.

  The imaging optical systems L1 and L2 constituting the stereo optical system L0 of the present embodiment have an angle of view of ± 40 degrees around the Z axis in the YZ plane, and around the Z axis in the XZ plane. It has an angle of view of ± 20 degrees. A reflecting surface having a rotationally asymmetric shape in order from the object side along the reference axis such that the reflecting surface of the second surface R2 is the first reflecting surface and the succeeding reflecting surfaces are the second reflecting surface and the third reflecting surface. Number the. At this time, in order to achieve high image quality over the entire screen while maintaining this angle of view, the first reflective surface has a deep concave shape having positive power.

  In this embodiment, an intermediate imaging plane is provided between the first reflection surface and the final reflection surface for all angle-of-view light fluxes. The final reflection surface is a reflection surface where a light beam incident on the optical imaging surface of the imaging optical systems L1 and L2 is reflected immediately before. In the present embodiment, the fifth reflective surface (R6) corresponds to the final reflective surface. By having the intermediate imaging surface, even in the case of an imaging optical system having a wide angle of view, it is possible to combine light rays of peripheral angle of view around the reference axis, and the area of the reflecting surface can be reduced.

  More preferably, among the plurality of reflecting surfaces having a rotationally asymmetric shape, the reflecting surface (first reflecting surface) closest to the object side and the reflecting surface (second reflecting surface) adjacent along the reference axis. At least one beam has an intermediate imaging point. In the case of an imaging optical system having a wide angle of view, the width of the angle of view is closely related as a parameter for determining the size of the first reflection surface. When the light is guided to the second reflection surface without intermediate image formation, the second reflection surface also becomes very large. On the other hand, if an intermediate imaging point is provided between the first reflection surface and the second reflection surface, rays of each angle of view can be collected in a narrow area even at a wide angle of view. The area after the surface can be reduced.

  More preferably, an intermediate imaging point is provided between the first reflection surface and the second reflection surface for all angle-of-view light fluxes. Also preferably, it is preferable to have an intermediate imaging surface M between the first reflection surface and the second reflection surface. By having an intermediate imaging plane M which forms an intermediate image at all angles of view not only at one angle of view, all off-axis chief rays reflected by the first reflection surface are grouped near the ray on the reference axis Can. As a result, it is possible to make the reflecting surface of the second reflecting surface smaller while shortening the distance between the first reflecting surface and the second reflecting surface. Thereby, miniaturization of each reflective surface can be achieved even at a wide angle of view of ± 40 degrees. The position of the intermediate image formation plane M is not limited to the position shown in FIG. Also, in the other embodiments described below, the intermediate imaging plane M is similarly provided in the imaging optical systems L1 and L2.

  Further, in the present embodiment, the imaging optical systems L1 and L2 constituting the stereo optical system L0 have a hollow reflection mirror configuration having a rotationally asymmetric shape. As a result, it is not necessary to increase the number of lenses for chromatic aberration correction, and it is possible to maintain a bright F value and high imaging performance with a small number of parts.

  Further, in the present embodiment, the reflection direction of the light beam on the even-numbered reflection surface and the reflection direction of the light beam on the odd-numbered reflection surface in the YZ plane are opposite to each other in the traveling direction of the light beam. The reflective surface having each rotationally asymmetric shape is constructed. For example, in the case of the imaging optical system L2 of the present embodiment, the first reflecting surface reflects light in the right direction along the reference axis after light incidence, while the second reflecting surface reflects it in the left direction. As a result, it becomes easy to cancel the decentration aberration generated on each reflecting surface, and it becomes possible to improve the image quality over the entire screen.

  Preferably, the imaging optical systems L1 and L2 are substantially the same optical system. If the angle of view or F number differs between the two optical systems, the range over which the distance can be measured is determined by the imaging optical system with a narrow angle of view, or if the depth of field is different, the distance measurement accuracy is degraded. It is not preferable because it

  FIG. 16 is a diagram showing the relationship between the stereo optical system L0 and the imaging optical systems L1 and L2. As shown in FIG. 16, let dsp be the length of the straight line connecting the centers (opening centers) SPO1 and SPO2 of the two aperture stops SP, and let dim be the length of the straight line connecting the centers of the two final imaging planes. At the same time, it is preferable to satisfy the following conditional expression (1).

dsp> dim ... (1)
As a result, the two aperture stops SP can be separated while the imaging surfaces of the two imaging optical systems L1 and L2 are close to each other. If conditional expression (1) is satisfied, it is preferable because a long baseline length can be obtained and the accuracy of calculating the distance from the parallax image can be increased. On the other hand, when the conditional expression (1) is not satisfied, the base length is too short, and the accuracy of calculating the distance is unfavorably reduced.

  Here, a plane in which the reference axis repeats reflection, that is, a plane including the bent reference axis (YZ plane) is referred to as an off-axial cross section (off axial cross section). In the imaging optical systems L1 and L2, the half angle of view on the Off-Axial cross section is ωy (angle of view in the Y-axis direction), and the half angle of view on the cross section perpendicular to the Off-Axial cross section is ωx (X-axis direction Angle of view). At this time, it is preferable to satisfy the following conditional expression (2).

ωy> ωx (2)
As a result, miniaturization can be achieved in the direction perpendicular to the off-axial cross section. This is useful when the application does not need to see the same range in the horizontal and vertical directions. For example, when the stereo optical system L0 of this embodiment is used for an on-vehicle camera, it is better to look wide in the horizontal direction such as a sidewalk or an oncoming car when monitoring the surroundings, but at least in the vertical direction If you can see it, there is no problem even if you narrow the viewing range compared to the horizontal direction. In such a case, by satisfying conditional expression (2), further miniaturization can be achieved, which is preferable.

  It is preferable that the final imaging surface of the two imaging optical systems L1 and L2 be inclined around the X axis with the point of intersection of the reference axis and the final imaging surface as a rotation center. Thereby, the final imaging plane of the two imaging optical systems L1 and L2 can be arranged on the XsYs plane.

  The average focal length in the YsZs plane of the two imaging optical systems L1 and L2 is fav. When the center position of the final imaging plane of the reference axis extended in the ray traveling direction is projected on the YsZs plane, two reference axes are at one point from the center positions of the final imaging plane of each of the imaging optical systems L1 and L2. The average distance to the intersection point is dav. At this time, it is preferable to satisfy the following conditional expression (3).

2.00 <dav / fav <8.00 ... (3)
In the conditional expression (2), the average focal length fav is represented by the following expression (4) when the focal length of the imaging optical system L1 in the YsZs plane is f1 and the focal length of the imaging optical system L2 is f2. Be done.

fav = (f1 + f2) / 2 (4)
Consider the case of projecting the center position of the final imaging plane and the reference axis extended in the ray traveling direction on the YsZs plane with respect to the imaging optical system L1. The distance from the center position of the final imaging plane of the imaging optical system L1 to the point where the two extended reference axes intersect at one point is d1. Similarly, in the imaging optical system L2, the distance from the center position of the final imaging surface of the imaging optical system L2 to the point at which two extended reference axes intersect at one point is d2. At this time, the average distance dav is expressed by the following equation (5).

dav = (d1 + d2) / 2 (5)
As the average distance dav becomes longer compared to the focal lengths f1 and f2 of the imaging optical systems L1 and L2, the distance between the final imaging planes formed by the two imaging optical systems L1 and L2 (Ys axis direction) Interval) becomes longer. At this time, in order to capture two images with one imaging element, a large imaging element is required, which is not preferable because it becomes large. Alternatively, the acute angle formed by the reference axes formed by the two imaging optical systems L1 and L2 is too small. At this time, the final reflection surface (fifth reflection surface (R6)) of the two imaging optical systems L1 and L2 interfere with each other, which is not preferable.

  More preferably, conditional expression (3) satisfies the following conditional expression (3a).

3.00 <dav / fav <7.00 ... (3a)
More preferably, conditional expression (3a) satisfies the following conditional expression (3b).

3.50 <dav / fav <6.50 (3b)
Also preferably, the final imaging planes of the two imaging optical systems L1 and L2 are on the same plane. Thereby, a parallax image can be easily obtained from two imaging optical systems using the conventional imaging device of planar shape.

  The numerical values of the conditional expressions will be described in the part of the numerical examples to be described later. According to the present embodiment, a stereo optical system that is compact and capable of distance measurement and can reduce the scale of information processing calculation while achieving both widening of angle and reduction of distortion, and an imaging apparatus using the same Can be provided.

Second Embodiment
Next, a second embodiment of the present invention will be described. The basic configuration of the stereo optical system L0 of this embodiment will be described with reference to FIG. The stereo optical system L0 of this embodiment has a long optical path (back focus) from the fifth reflection surface to the final imaging surface, and is easy to put a wavelength selective filter or the like in the vicinity of the final imaging surface. It differs from the first embodiment. The wavelength selective filter is preferable because it is possible to select ultraviolet light, infrared light, visible light, and information to be acquired by a filter exchange mechanism.

  FIG. 5 shows the appearance of distortion in the present embodiment (Numerical Example 2). In FIG. 5, the horizontal axis represents coordinate values (corresponding to an X angle of view) on the image plane in the X axis direction, and the vertical axis represents coordinate values (corresponding to a Y angle of view) on the image plane in the Y axis direction. Also, the distortion-free ideal grid (Paraxial FOV) and the grid of actual ray tracing results (Actual FOV) are superimposed and drawn. FIG. 6 shows transverse aberration diagrams at evaluation positions 1 to 5. Further, in the lateral aberration diagram of FIG. 6, the horizontal axis is taken as the X axis or Y axis on the pupil plane, and the vertical axis is meant for the amount of aberration on the image plane. The wavelength of the evaluation beam is d-line. ω is a half angle of view. In all aberration diagrams, when each numerical value example to be described later is expressed in mm, it is drawn on a scale of lateral aberration ± 0.025 mm.

  According to the present embodiment, a stereo optical system that is compact and capable of distance measurement and can reduce the scale of information processing calculation while achieving both widening of angle and reduction of distortion, and an imaging apparatus using the same Can be provided.

Third Embodiment
Next, a third embodiment of the present invention will be described. The basic configuration of the stereo optical system L0 of the present embodiment will be described with reference to FIG. The stereo optical system L0 of the present embodiment differs from the first embodiment in that the optical path (back focus) from the fifth reflection surface to the final image forming surface is shortened to further miniaturize. If the thickness of the stereo optical system L0 can be reduced in the Zs axis direction, the weight of the holding member such as a lens barrel can also be reduced, which is preferable because it can be easily mounted on a UAV or the like.

  FIG. 8 shows the state of distortion in the present embodiment (Numerical Example 2). In FIG. 8, the horizontal axis represents coordinate values (corresponding to an X angle of view) on the image plane in the X axis direction, and the vertical axis represents coordinate values (corresponding to a Y angle of view) on the image plane in the Y axis direction. Also, the distortion-free ideal grid (Paraxial FOV) and the grid of actual ray tracing results (Actual FOV) are superimposed and drawn. FIG. 9 shows transverse aberration diagrams at evaluation positions 1 to 5. Further, in the lateral aberration diagram of FIG. 9, the horizontal axis is taken as the X axis or Y axis on the pupil plane, and the vertical axis is meant for the amount of aberration on the image plane. The wavelength of the evaluation beam is d-line. ω is a half angle of view. In all aberration diagrams, when each numerical value example to be described later is expressed in mm, it is drawn on a scale of lateral aberration ± 0.025 mm.

  According to the present embodiment, a stereo optical system that is compact and capable of distance measurement and can reduce the scale of information processing calculation while achieving both widening of angle and reduction of distortion, and an imaging apparatus using the same Can be provided.

  In each embodiment, as a modification, cover glasses may be disposed before and after the aperture stop SP so that dust and the like do not enter the interior of the stereo optical system L0. In addition, various filters such as a low pass filter and a wavelength selection filter, or a cover glass may be disposed closer to the object than the imaging element IMG0. Hereinafter, numerical value examples 1 to 3 respectively corresponding to the first to third embodiments will be described. Since the imaging optical systems L1 and L2 of each embodiment use the same optical system, the contents of the imaging optical system L2 are described in the following numerical examples, and the description of the contents of the imaging optical system L1 is omitted. Do. FIG. 14 is a layout diagram of final imaging planes IMG1 and IMG2 on the imaging element IMG0 common to the first to third embodiments.

(Numerical Example 1)
The distance from the object plane to the aperture stop SP is infinite, and the angle of view is X: ± 20 degrees, Y: ± 40 degrees. The focal length is X: 2.87 mm, Y: 2.83 mm. The image plane size is x: 2.082 mm, y: 4.8 mm. The entrance pupil (aperture stop SP) is circular and its diameter is 1.5 mm. The F value in the X-axis direction is 1.91 and the F value in the Y-axis direction is 1.92. The reflecting surfaces in the present embodiment are all configured by rotationally asymmetric surfaces, and when each reflecting surface is projected onto the XZ plane, it has a rectangular shape. The rotationally asymmetric surface shape is given by equation (B).

Surface data surface number Xi Yi Zi Di θxi θyi
1 (SP) 0.00 0.00 0.00 16.50 0.00 0.00 aperture
2 (R2) 0.00 0.00 16.50 27.50 25.00 0.00 1st reflective surface
3 (R3) 0.00 -21.07 -1.18 20.50 -36.50 0.00 2nd reflective surface
4 (R4) 0.00-29.08 17.69 20.50 24.00 0.00 Third reflective surface
5 (R5) 0.00 -37.74 -0.89 20.50 -33.00 0.00 Fourth reflection surface
6 (R6) 0.00-51.19 14. 59 21. 91 26.00 0.00 Image plane of the fifth reflective surface 0.00-55. 35-6. 75-1 1 00 0.00 IMG 1, 2

Rotationally asymmetric surface data second surface (R2) first reflection surface
C20 = -2.1083E-02 C02 = -1.9062E-02 C21 = -5.3706E-06
C03 = -1.0783E-04 C40 = -9.8216E-06 C22 = -7.2322E-06
C04 = -6.6462 E-06 C41 = 3.3789 E-07 C23 = 5.8855 E-08
C05 = 1.2921 E-07 C60 = 1.5916 E-07 C42 = 2.8131 E-08
C24 = 9.1731 E-09 C06 = 5.4053 E-09 C60 = 1.7743 E-09
C43 = 7.7018 E-10 C25 = 2.7041 E-10 C07 = -7.3999 E-10
C80 = -9.4570E-10 C62 = -1.3043E-11 C44 = -9.8469E-12
C26 = -2.8803E-11 C08 = -3.8363E-11

Third surface (R3) Second reflective surface
C20 = -2.2290 E-02 C02 = -1.5436 E-02 C21 = 3.0179 E-04
C03 = 1.2301E-03 C40 = -1.8460E-05 C22 = 8.7500E-06
C04 = -2.8366E-05 C41 = -5.4030E-06 C23 = 3.7340E-08
C05 = -1.4290E-06 C60 = -2.8325E-07 C42 = -1.0483E-06
C24 = 1.1108E-08 C06 = 1.7965E-07 C60 = -1.3624E-07
C43 = -1.5749E-07 C25 = -3.5693E-08 C07 = 6.3169E-09
C80 = 4.5763E-08 C62 = 8.2309E-08 C44 = 1.0904E-08
C26 = 3.0443E-09 C08 = -1.0202E-09

Fourth surface (R4) Third reflective surface
C20 = -1.8373E-02 C02 = -9.5725E-03 C21 = 2.2499E-05
C03 = 1.6044E-04 C40 = -7.5926E-06 C22 = -9.2543E-06
C04 = 6.7798E-07 C41 = -1.5985E-07 C23 = 3.1090E-08
C05 = -6.1270E-08 C60 = -1.9291E-09 C42 = -9.8197E-09
C24 = -7.9524E-09 C06 = -5.5537E-09 C60 = 5.4368E-10
C43 = 3.8048E-10 C25 = -1.0940E-10 C07 = -1.1075E-10
C80 = -1.3858 E-12 C62 = 2.5615 E-11 C44 = -5.4602 E-11
C26 = 4.7002E-11 C08 = -2.9674E-11

Fifth surface (R5) Fourth reflective surface
C20 = -8.0733E-02 C02 = -8.5416 E-03 C21 = -1.1258E-03
C03 = -1.3124E-04 C40 = -1.2440E-03 C22 = -2.6615E-04
C04 = -2.9658E-05 C41 = -9.3874E-05 C23 = -1.2101E-05
C05 = -1.4412 E-06 C60 = 4.4922 E-05 C42 = -1.3598 E-05
C24 = -5.0439E-06 C06 = -1.9912E-07 C60 = 3.4539E-06
C43 = -1.2107E-06 C25 = -2.8823E-07 C07 = -3.5184E-09
C80 = -8.0363E-06 C62 = -3.1719E-07 C44 = 4.4547E-09
C26 = 4.3268E-08 C08 = 1.6535E-10

Sixth surface (R6) Fifth reflective surface
C20 = -2.3549E-02 C02 = -1.4857E-02 C21 = 2.6640E-05
C03 = 1.6841E-05 C40 = -1.4024E-05 C22 = -1.7537E-05
C04 = -5.1626E-06 C41 = 6.4278 E-08 C23 = 3.9511 E-08
C05 = 3.3663E-08 C60 = -1.6124E-08 C42 = -3.6300E-08
C24 = -1.9936E-08 C06 = -6.4908E-09 C60 = 6.2117E-12
C43 = 1.4904 E-09 C25 = 8.7835 E-10 C07 = -1.0945 E-10
C80 = -3.1885E-11 C62 = -2.1066E-11 C44 = -1.3538E-10
C26 = -5.3118 E-11 C08 = 2.2457 E-11

Focal length data of axial luminous flux of each reflecting surface
i of fix and fiy corresponds to the i-th reflective surface.
fix represents the focal length in the X section, and fiy represents the focal length in the Y section.
fx represents the focal length of the entire system at the X cross section, and fy represents the focal length of the entire system at the Y cross section.
f1x = 13.084 mm f1y = 11.887 mm
f2x = -13.953 mm f2y = -13.019 mm
f3x = 14.894 mm f3y = 23859 mm
f4x = -3.692 mm f4y = -24.547 mm
f5x = 11.812 mm f5y = 15.124 mm
fx = 2.867 mm fy = 2.830 mm

Since the shape data of each reflecting surface is rectangular, twice the value of each of Eaix and Eaiy corresponds to the length of the side of the rectangle. The longer side of each side is called the "long side" and the shorter side is called the "short side". The same applies to the following numerical examples.
In addition, i of Eaix and Eaiy corresponds to the i-th reflective surface.
Eaix represents a half of the length of the side in the X cross section, and Eaiy represents a half of the length of the side in the Y cross section.

Ea1x = 7.29 mm Ea1y = 13.46 mm
Ea2x = 4.37 mm Ea2y = 6.82 mm
Ea3x = 10.73 mm Ea3y = 8.22 mm
Ea4x = 1.91 mm Ea4y = 4.35 mm
Ea5x = 9.11 mm Ea5y = 7.70 mm

dsp = 117.1
dim = 6.4
ω _x = ± 20 degrees ω _y = ± 40 degrees
d1 = 16.77
d2 = 16.77
f1 = 2.830
f2 = 2.830
dav = 16.77
fav = 2.830

(Numerical Example 2)
The distance from the object plane to the aperture stop SP is infinite, and the angle of view is X: ± 20 degrees, Y: ± 40 degrees. The focal length is X: 2.86 mm, Y: 2.83 mm. The image plane size is x: 2.082 mm, y: 4.8 mm. The entrance pupil (aperture stop SP) is circular and its diameter is 1.5 mm. The F value in the X-axis direction is 1.91 and the F value in the Y-axis direction is 1.94. The reflecting surfaces in the present embodiment are all configured by rotationally asymmetric surfaces, and when each reflecting surface is projected onto the XZ plane, it has a rectangular shape. The rotationally asymmetric surface shape is given by equation (B).

Surface data surface number Xi Yi Zi Di θxi θyi
1 (SP) 0.00 0.00 0.00 16.50 0.00 0.00 aperture
2 (R2) 0.00 0.00 16.50 27.00 25.00 0.00 1st reflective surface
3 (R3) 0.00 -20.68 -0.86 21.50 -33.00 0.00 Second reflective surface
4 (R4) 0.00 -26.61 19.81 22.50 24.00 0.00 Third reflective surface
5 (R5) 0.00-38.53 0.73 24. 50-43.00 0.00 Fourth reflection surface
6 (R6) 0.00 -58.35 15.13 34.60 33.50 0.00 Image plane of the fifth reflective surface 0.00 -66.14 -18.58 -13.00 0.00 IMG 1,2

Rotationally asymmetric surface data second surface (R2) first reflection surface
C20 = -1.9750E-02 C02 = -2.0001E-02 C21 = -4.1410E-06
C03 = -1.0050E-04 C40 = 6.5089E-06 C22 = -2.7138E-07
C04 = -8.3210E-06 C41 = -1.4237E-08 C23 = 3.8332E-07
C05 = -6.7157E-09 C60 = -6.0088E-08 C42 = -1.2266E-08
C24 = 2.7699 E-08 C06 = 1.8921 E-09 C60 = 1.3661 E-09
C43 = 1.7521 E-10 C25 = 1.2924 E-09 C07 = -3.3266 E-10
C80 = 4.6821 E-10 C62 = 6.5690 E-11 C44 = -2.8772 E-11
C26 = -6.3987E-12 C08 = -2.2304E-11

Third surface (R3) Second reflective surface
C20 = -1.1301E-02 C02 = -2.3824E-02 C21 = 5.1853E-04
C03 = 2.7676E-03 C40 = -1.7298E-05 C22 = -8.6299E-05
C04 = -1.5444E-04 C41 = 5.7041E-06 C23 = 1.1015E-05
C05 = 1.1884 E-05 C60 = 5.2959 E-08 C42 = -1.2392 E-06
C24 = -2.6190E-06 C06 = -1.2825E-06 C60 = -2.4132E-08
C43 = 1.2519E-07 C25 = 4.0196E-07 C07 = 1.0481E-07
C80 = -2.0193 E-09 C62 = 1.1236 E-08 C44 =-8.3473 E-09
C26 = -2.0372E-08 C08 = -3.5478E-09

Fourth surface (R4) Third reflective surface
C20 = -1.5381E-02 C02 = -9.4433E-03 C21 = -4.8941E-05
C03 = 2.5686 E-04 C40 = -3.6217 E-06 C22 =-1.4979 E-05
C04 = 1.0664E-05 C41 = 1.4366E-07 C23 = -4.3390E-07
C05 = 6.2941E-07 C60 = -1.4222E-09 C42 = -3.5277E-09
C24 = -3.5152 E-08 C06 = 3.0693 E-08 C60 = 3.3911 E-10
C43 = 3.3406 E-10 C25 = -1.6438 E-09 C07 = 1.4417 E-09
C80 = -1.4330 E-11 C62 = 4.920 E-11 C44 = 4.2387 E-12
C26 = -4.1780E-11 C08 = 3.1378E-11

Fifth surface (R5) Fourth reflective surface
C20 = -1.1121 E-01 C02 = -8.6804 E-03 C21 = -3.0158 E-03
C03 = 6.2725E-05 C40 = -1.6793E-03 C22 = -2.4409E-04
C04 = -1.4311E-05 C41 = -1.3192E-04 C23 = -7.9405E-06
C05 = 1.2376E-07 C60 = -4.1737E-05 C42 = -1.4777E-05
C24 = -1.9762E-06 C06 = -3.0936E-08 C60 = -4.2105E-06
C43 = -1.1558E-06 C25 = -1.0052E-07 C07 = 1.2267E-10
C80 = -2.6568E-06 C62 = -1.0462E-06 C44 = -1.0392E-07
C26 = 2.5897E-09 C08 = -1.9610E-10

Sixth surface (R6) Fifth reflective surface
C20 = -1.9332E-02 C02 = -1.0363E-02 C21 = -6.1723E-06
C03 = 1.2595E-05 C40 = -7.2754E-06 C22 = -7.5142E-06
C04 = -1.9237E-06 C41 = -1.3298E-09 C23 = 6.0055E-09
C05 = 6.2133 E-09 C60 = -5.6655 E-09 C42 = -9.2351 E-09
C24 = -6.4478 E-09 C06 = -9.1306 E-10 C60 =-8.7282 E-12
C43 = 3.4691 E-12 C25 = 6.7088 E-11 C07 = 2.7296 E-12
C80 = -4.7559E-12 C62 = -1.3729 E-11 C44 = -4.5294 E-12
C26 = 7.1144E-14 C08 = -1.1136E-14

Focal length data of axial luminous flux of each reflecting surface
i of fix and fiy corresponds to the i-th reflective surface.
fix represents the focal length in the X section, and fiy represents the focal length in the Y section.
fx represents the focal length of the entire system at the X cross section, and fy represents the focal length of the entire system at the Y cross section.
f1x = 13.967 mm f1y = 11.328 mm
f2x = -26.377 mm f2y = -8.801 mm
f3x = 17.792 mm f3y = 24.185 mm
f4x = -3.074 mm f4y =-21.063 mm
f5x = 15.508 mm f5y = 20.117 mm
fx = 2.863 mm fy = 2.833 mm

Since the shape data of each reflecting surface is rectangular, twice the value of each of Eaix and Eaiy corresponds to the length of the side of the rectangle. The longer side of each side is called the "long side" and the shorter side is called the "short side". The same applies to the following numerical examples.
In addition, i of Eaix and Eaiy corresponds to the i-th reflective surface.
Eaix represents a half of the length of the side in the X cross section, and Eaiy represents a half of the length of the side in the Y cross section.

Ea1x = 7.26 mm Ea1y = 13.30 mm
Ea2x = 5.20 mm Ea2y = 5.47 mm
Ea3x = 10.41 mm Ea3y = 9.57 mm
Ea4x = 2.04mm Ea4y = 7.17mm
Ea5x = 10.01 mm Ea5 y = 12.87 mm

dsp = 138.68
dim = 6.4
ω _x = ± 20 degrees ω _y = ± 40 degrees
d1 = 14.23
d2 = 14.23
f1 = 2.833
f2 = 2.833
dav = 14.23
fav = 2.833

(Numerical Example 3)
The distance from the object plane to the aperture stop SP is infinite, and the angle of view is X: ± 20 degrees, Y: ± 40 degrees. The focal length is X: 2.86 mm, Y: 2.81 mm. The image plane size is x: 2.082 mm, y: 4.8 mm. The entrance pupil (aperture stop SP) is circular and its diameter is 1.5 mm. The F value in the X axis direction is 1.90, and the F value in the Y axis direction is 1.95. The reflecting surfaces in the present embodiment are all configured by rotationally asymmetric surfaces, and when each reflecting surface is projected onto the XZ plane, it has a rectangular shape. The rotationally asymmetric surface shape is given by equation (B).

Surface data surface number Xi Yi Zi Di θxi θyi
1 (SP) 0.00 0.00 0.00 16.50 0.00 0.00 aperture
2 (R2) 0.00 0.00 16.50 27.00 25.00 0.00 1st reflective surface
3 (R3) 0.00 -20.68 -0.86 21.50 -38.00 0.00 2nd reflective surface
4 (R4) 0.00 -30.11 18.47 21.50 24.00 0.00 Third reflection surface
5 (R5) 0.00 -38.16-1.47 22.50 -28.00 0.00 4th reflective surface
6 (R6) 0.00 -50.74 17.19 20.60 25.00 0.00 Image plane of the fifth reflective surface 0.00-56.42-2.61-16.00 0.00 IMG 1, 2

Rotationally asymmetric surface data second surface (R2) first reflection surface
C20 = -2.1752E-02 C02 = -1.8762E-02 C21 = 4.5605E-05
C03 = -1.1903E-04 C40 = -4.4143E-06 C22 = -8.8552E-06
C04 = -1.0364E-05 C41 = 3.7019E-07 C23 = 1.1859E-07
C05 = -1.2062E-07 C60 = -1.7188E-08 C42 = 6.3369E-09
C24 = 1.8695 E-08 C06 = 5.9282 E-09 C60 = -5.4593 E-09
C43 = -1.2181 E-09 C25 = 9.6491 E-10 C07 = -8.5169 E-11
C80 = -3.8137E-10 C62 = -3.3888 E-10 C44 = -6.4926E-11
C26 = -1.0921E-11 C08 = -2.0387E-11

Third surface (R3) Second reflective surface
C20 = -2.9740E-02 C02 = -1.7248E-02 C21 = -2.8145E-04
C03 = 1.0149E-03 C40 = -3.5696E-05 C22 = 3.2040E-05
C04 = -6.9447E-08 C41 = -1.0255E-05 C23 = -4.1195E-06
C05 = -5.5308E-06 C60 = -1.4069E-07 C42 = 2.8538E-07
C24 = 1.0658E-07 C06 = 4.6121E-07 C60 = -3.5895E-08
C43 = -8.4108E-08 C25 = -5.2627E-08 C07 = 1.4631E-08
C80 = -2.7804E-09 C62 = -3.4851E-08 C44 = -1.5725E-08
C26 = 3.7679E-09 C08 = -2.6396E-09

Fourth surface (R4) Third reflective surface
C20 = -1.8431 E-02 C02 = -9.4522 E-03 C21 = 2.0620 E-05
C03 = 2.7832E-05 C40 = -7.6258E-06 C22 = -8.1940E-06
C04 = -4.8882E-07 C41 = -2.7783E-08 C23 = 1.2141E-08
C05 = -1.3191 E-07 C60 = -4.2573 E-09 C42 = -6.9482 E-09
C24 = -7.8375E-09 C06 = -5.2620E-09 C60 = 3.7623E-13
C43 = -5.1286 E-10 C25 = -5.0713 E-10 C07 = 7.7427 E-11
C80 = -1.2239E-11 C62 = -2.0310 E-11 C44 = 2.1960 E-11
C26 = 2.8146 E-11 C08 = 1.3207 E-11

Fifth surface (R5) Fourth reflective surface
C20 = -6.7863E-02 C02 = -6.9259E-03 C21 = -1.0418E-03
C03 = -4.3290E-04 C40 = -8.9955 E-04 C22 = -2.6960E-04
C04 = -2.9782E-05 C41 = -3.8668E-05 C23 = -1.4324E-05
C05 = -2.7579E-06 C60 = -7.1171E-06 C42 = -8.8544E-06
C24 = -3.0115E-06 C06 = -3.3960E-07 C60 = -4.8234E-06
C43 = -2.3326E-06 C25 = -6.1996E-07 C07 = -2.8021E-08
C80 = -1.7552E-06 C62 = -1.0971E-06 C44 = -4.8498E-07
C26 = -3.8503E-08 C08 = -5.6218E-10

Sixth surface (R6) Fifth reflective surface
C20 = -2.2785E-02 C02 = -1.4606E-02 C21 = 2.3030E-05
C03 = -3.2261E-05 C40 = -1.2786E-05 C22 = -1.6104E-05
C04 = -2.5347E-06 C41 = 2.7110E-08 C23 = -6.7259E-10
C05 = -7.7368E-08 C60 = -1.1785E-08 C42 = -2.4514E-08
C24 = -1.0989 E-08 C06 = 2.3414 E-09 C60 = 1.7760 E-10
C43 = 4.2642 E-11 C25 = 1.0319 E-09 C07 = -8.9921 E-10
C80 = -3.4260 E-11 C62 =-9.4841 E-11 C44 =-2.4550 E-11
C26 = -1.4396E-10 C08 = 4.5861E-11

Focal length data of axial luminous flux of each reflecting surface
i of fix and fiy corresponds to the i-th reflective surface.
fix represents the focal length in the X section, and fiy represents the focal length in the Y section.
fx represents the focal length of the entire system at the X cross section, and fy represents the focal length of the entire system at the Y cross section.
f1x = 12.682 mm f1y = 12.077 mm
f2x = -10. 668 mm f2y =-11.422 mm
f3x = 14.848 mm f3y = 24.162 mm
f4x = -4.172 mm f4y = -31.871 mm
f5x = 12.106 mm f5y = 15.513 mm
fx = 2.858 mm fy = 2.813 mm

Since the shape data of each reflecting surface is rectangular, twice the value of each of Eaix and Eaiy corresponds to the length of the side of the rectangle. The longer side of each side is called the "long side" and the shorter side is called the "short side". The same applies to the following numerical examples.
In addition, i of Eaix and Eaiy corresponds to the i-th reflective surface.
Eaix represents a half of the length of the side in the X cross section, and Eaiy represents a half of the length of the side in the Y cross section.

Ea1x = 7.27 mm Ea1y = 13.48 mm
Ea2x = 4.23 mm Ea2y = 6.60 mm
Ea3x = 14.65 mm Ea3y = 8.78 mm
Ea4x = 2.64 mm Ea4y = 5.17 mm
Ea5x = 11.98 mm Ea5y = 7.53 mm

dsp = 119.24
dim = 6.4
ω _x = ± 20 degrees ω _y = ± 40 degrees
d1 = 11.61
d2 = 11.61
f1 = 2.813
f2 = 2.813
dav = 11.61
fav = 2.813

  Table 1 shows values regarding conditional expressions (1) to (3) in each numerical example. The stereo optical system L0 according to the first to third embodiments can be applied to a surveillance camera, an on-vehicle camera, or an unmanned aerial vehicle such as a UAV (Unmanned Aerial Vehicle) represented by a drone. . Thus, according to each embodiment, it is possible to realize a stereo optical system that is compact and capable of distance measurement and can reduce the information processing operation scale while achieving both widening of the angle and reduction of distortion. it can.

Fourth Embodiment
Next, the on-vehicle camera 10 including the stereo optical system according to the first to third embodiments and the on-vehicle camera system (driving support apparatus) 600 including the on-vehicle camera 10 will be described. FIG. 17 is a configuration diagram of the on-vehicle camera 10 and the on-vehicle camera system 600. The on-vehicle camera system 600 is a device installed in a vehicle such as a car and supporting driving of the vehicle based on the image information of the surroundings of the vehicle acquired by the on-vehicle camera 10. FIG. 18 is a schematic view of a vehicle 700 equipped with an on-vehicle camera system 600. As shown in FIG. Although FIG. 18 shows the case where the imaging range 50 of the on-vehicle camera 10 is set in front of the vehicle 700, the imaging range 50 may be set behind the vehicle 700.

  As shown in FIG. 17, the on-vehicle camera system 600 includes an on-vehicle camera 10, a vehicle information acquisition device 20, a control device (ECU: electronic control unit) 30, and an alarm device 40. The on-vehicle camera 10 further includes an imaging unit 1, an image processing unit 2, a parallax calculation unit 3, a distance calculation unit 4, and a collision determination unit 5. The image processing unit 2, the parallax calculation unit 3, the distance calculation unit 4, and the collision determination unit 5 constitute a processing unit. The imaging unit 1 includes an optical system and an imaging device according to any of the above-described embodiments.

  FIG. 19 is a flowchart showing an operation example of the on-vehicle camera system 600. Hereinafter, the operation of the on-vehicle camera system 600 will be described along the flowchart.

  First, in step S1, an object (subject) around the vehicle is imaged using the imaging unit 1, and a plurality of image data (parallax image data) are acquired. Subsequently, in step S2, vehicle information is acquired from the vehicle information acquisition device 20. The vehicle information is information including the vehicle speed of the vehicle, the yaw rate, the steering angle, and the like. Subsequently, in step S <b> 3, the image processing unit 2 performs image processing on a plurality of image data acquired by the imaging unit 1. Specifically, image feature analysis is performed to analyze feature amounts such as the amount and direction of edges in image data, and density values. Here, the image feature analysis may be performed on each of the plurality of image data, or may be performed on only a part of the plurality of image data.

  Subsequently, in step S <b> 4, parallax (image shift) information between the plurality of pieces of image data acquired by the imaging unit 1 is calculated by the parallax calculation unit 3. A known method such as an SSDA method or an area correlation method can be used as a method of calculating disparity information, and thus the description thereof will be omitted in this embodiment. In the steps S2, S3 and S4, the processing may be performed in the above order or may be performed in parallel with each other.

  Subsequently, in step S5, the distance calculation unit 4 calculates distance information (distance information) with the object captured by the imaging unit 1. That is, the distance calculation unit 4 calculates distance information of the subject based on the plurality of images formed respectively through the plurality of optical systems. The distance information can be calculated based on the parallax information calculated by the parallax calculation unit 3 and the internal parameter and the external parameter of the imaging unit 1. Here, the distance information is information on the relative position to the object such as the distance to the object, defocus amount, image shift amount, etc., and the distance value of the object in the image is directly Or may indirectly represent information corresponding to the distance value.

  Subsequently, in step S6, the collision determination unit 5 determines whether the distance information calculated by the distance calculation unit 4 is included in the range of the preset distance set in advance. Thus, it is possible to determine whether an obstacle is present within the set distance around the vehicle and to determine the possibility of collision between the vehicle and the obstacle. The collision determination unit 5 determines that there is a collision possibility if there is an obstacle within the set distance (step S7), and determines that there is no collision possibility if there is no obstacle within the set distance (step S8) ).

  Next, when the collision determination unit 5 determines that there is a collision possibility (step S7), the collision determination unit 5 notifies the control device 30 or the alarm device 40 of the determination result. At this time, the control device 30 controls the vehicle based on the determination result of the collision determination unit 5, and the alarm device 40 issues an alarm based on the determination result of the collision determination unit 5.

  For example, the control device 30 performs control such as applying a brake to the vehicle, returning an accelerator, or generating a control signal for causing each wheel to generate a braking force to suppress an output of an engine or a motor. Further, the alarm device 40 sounds an alarm such as a sound to a user (driver) of the vehicle, displays alarm information on a screen of a car navigation system or the like, gives a vibration to a seat belt or steering wheel, etc. I do.

  As mentioned above, according to the vehicle-mounted camera system 600 which concerns on this embodiment, an obstacle can be detected effectively by said process, and it becomes possible to avoid the collision with a vehicle and an obstacle. In particular, by applying the optical system according to each of the above-described embodiments to the on-vehicle camera system 600, the entire on-vehicle camera 10 can be miniaturized to enhance the freedom of arrangement while detecting obstacles and determining collisions over a wide angle of view. It will be possible to do.

  In addition, various embodiments can be considered for the calculation of distance information. As an example, a case where a pupil division type imaging device having a plurality of pixel units regularly arranged in a two-dimensional array is adopted as an imaging device of the imaging unit 1 will be described. In the pupil division type imaging device, one pixel unit is composed of a micro lens and a plurality of photoelectric conversion units, receives a pair of light beams passing through different areas in the pupil of the optical system, and makes a pair of image data It can be output from each photoelectric conversion unit.

  Then, the image shift amount of each area is calculated by correlation calculation between the pair of image data, and the distance calculation unit 4 calculates image shift map data representing the distribution of the image shift amount. Alternatively, the distance calculation unit 4 may further convert the image shift amount into a defocus amount, and generate defocus map data representing the distribution of the defocus amount (distribution on the two-dimensional plane of the captured image). In addition, the distance calculation unit 4 may acquire distance map data of an interval with an object to be converted from the defocus amount.

  In the present embodiment, the on-vehicle camera system 600 is applied for driving assistance (collision damage reduction), but the invention is not limited thereto. For example, the on-vehicle camera system 600 may be used for cruise control (including all vehicle speed tracking function) and automatic driving. It may apply. In addition, the on-vehicle camera system 600 can be applied not only to a vehicle such as a host vehicle but also to a mobile object (mobile device) such as a ship, an aircraft, or an industrial robot. Further, the present invention can be applied not only to the on-vehicle camera 10 and the moving body according to the present embodiment, but also to devices that widely use object recognition, such as the Intelligent Transportation System (ITS).

  The imaging optical system of each embodiment is preferably applied to an imaging apparatus capable of detecting a subject such as a person using visible light and infrared light (far infrared light) or both of them. Not limited to this. The stereo optical system according to each embodiment can be applied not only to surveillance cameras and in-vehicle cameras but also to various imaging devices such as video cameras, digital still cameras, and cameras mounted on UAVs. According to each embodiment, while achieving both widening of the angle and reduction of distortion, it is possible to miniaturize and measure distance, and to reduce the information processing operation scale. For this reason, according to each embodiment, it is possible to provide an optical system, an imaging device, a distance measuring device, and an on-vehicle camera system capable of distance measurement at a small size and at low cost.

  As mentioned above, although the preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  For example, the optical system according to each embodiment described above can be applied to a projection apparatus as a projection optical system. In this case, the display surface of a display element such as a liquid crystal panel (spatial modulator) is disposed at the position of the reduction surface of the optical system. However, when the optical system is applied to a projection apparatus, the object side and the image side are reversed and the light path is reversed. That is, a configuration in which an image displayed on the display surface (reduction surface) of the display element disposed on the object side is projected (imaged) on a projection surface (enlarged surface) such as a screen disposed on the image side by the optical system. Can be taken. Also in this case, as in the case of applying the optical system to the imaging apparatus, it is desirable to satisfy each conditional expression in each embodiment. Further, when the optical system of each embodiment is applied to a projection apparatus, the luminous flux (F value) is determined by the illumination system disposed on the reduction side of the optical system, so the aperture stop SP (R1) as the aperture is disposed. do not have to. In this case, the position of the aperture is defined as the exit pupil.

  When the optical system of each embodiment is used as an imaging optical system, the reduction plane (reduction side conjugate plane) corresponds to an image plane (image plane), and the enlargement plane (magnification side conjugate plane) corresponds to an object plane (object plane). Do. Further, in the case of the imaging optical system, the reduction side (the reduction conjugate side) corresponds to the image side, and the enlargement side (the enlargement conjugate side) corresponds to the object side. On the other hand, when the optical system of each embodiment is used as a projection optical system, the reduction plane (reduction side conjugate plane) corresponds to the object plane (display plane), and the enlargement plane (magnification side conjugate plane) corresponds to the image plane (projection plane). Do. In the case of a projection optical system, the reduction side (reduction conjugate side) corresponds to the object side (display side), and the enlargement side (magnification conjugate side) corresponds to the image side (projection side).

L0 Stereo optical system (optical system)
L1 Imaging optical system (first imaging optical system)
L2 Imaging optical system (second imaging optical system)
R2 to R6 Reflective surface SP Aperture stop

Claims (18)

An optical system for forming an image of an object,
First and second imaging optical systems, and first and second aperture stops disposed on the optical paths of the first and second imaging optical systems,
The straight line connecting the opening centers of the first and second aperture stops as the origin, and the straight line with the direction from the opening center of the first aperture stop to the opening center of the second aperture stop being positive When a straight line perpendicular to the Ys axis passing through the Ys axis and the origin according to the definition of the right-handed coordinate system is taken as an Xs axis, and a straight line perpendicular to the Xs axis and the Ys axis passing through the origin is a Zs axis,
The first and second images formed by each of the first and second imaging optical systems are arranged along the direction of the Ys axis,
Paths of reference rays passing through the centers of the apertures of the first and second aperture stops to the center of the reduction plane on the XsYs plane are taken as first and second reference axes,
When the first and second extension axes obtained by extending the first and second reference axes from the reduction plane in the traveling direction of the reference beam are projected onto the YsZs plane, the first and second extension axes are An optical system characterized in that the extension axes of the two intersect with each other. Each of the first and second imaging optical systems has a plurality of reflective surfaces having a rotationally asymmetric shape for bending an optical path,
The optical system according to claim 1, wherein a surface normal at an intersection of at least one of the plurality of reflecting surfaces with the reference axis is inclined with respect to the reference axis.   Each of the first and second imaging optical systems forms at least one intermediate imaging surface between the reduction surface and the reflection surface closest to the magnification side among the plurality of reflection surfaces. The optical system according to claim 2.   Each of the first and second imaging optical systems is an intermediate connection of at least one light beam between the reflection surface on the most enlargement side among the plurality of reflection surfaces and the reflection surface adjacent along the reference axis. The optical system according to claim 2 or 3, which forms an image point.   The aperture stop of each of the first and second imaging optical systems is provided on an enlargement side of the reflection surface on the enlargement side among the plurality of reflection surfaces. The optical system according to any one of 4.   Regarding each of the first and second imaging optical systems, the reflection direction of light rays at the even-numbered reflecting surface and the odd-numbered reflecting surface, counting from the reflecting surface on the expansion side among the plurality of reflecting surfaces The optical system according to any one of claims 2 to 5, wherein the reflection direction of the light beam at is opposite to each other in the traveling direction of the light beam along the reference axis.   The optical system according to any one of claims 1 to 6, wherein each of the first and second imaging optical systems has a hollow mirror configuration. Assuming that the length of a straight line connecting the centers of the two aperture stops is dsp, and the length of the straight line connecting the centers of the two reduced surfaces is dim:
dsp> dim
The optical system according to any one of claims 1 to 7, wherein the following condition is satisfied. Assuming that the angle of view in the X-axis direction of each of the first and second imaging optical systems is ωx, and the angle of view in the Y-axis direction is ωy,
ωy> ωx
The optical system according to any one of claims 1 to 8, wherein the following condition is satisfied.   10. The image forming apparatus according to claim 1, wherein each of the reduction surfaces of the first and second imaging optical systems is inclined about an X-axis with a point of intersection of the reference axis and the reduction surface as a rotation center. The optical system according to any one of the above.   The optical system according to any one of claims 1 to 10, wherein the reduction surfaces of the first and second imaging optical systems are on the same plane. When the average focal length on the YsZs plane of the first and second imaging optical systems is fav, and the center of the reference axis and the reduction plane is projected on the YsZs plane, the first and second resultants are obtained. Assuming that the average distance from the center of each reduction plane of the image optical system to the point where the two reference axes intersect is dav
2.00 <dav / fav <8.00
The optical system according to any one of claims 1 to 11, characterized in that An optical system according to any one of claims 1 to 12;
And an imaging device for receiving an image formed by the optical system.   The imaging apparatus according to claim 13, wherein the optical system forms the first and second images having parallax with each other in different areas of the imaging device.   A distance measuring apparatus comprising: the imaging device according to claim 13 for acquiring image data of an object; and a distance calculation unit for acquiring distance information to the object based on the image data.   An on-vehicle camera system comprising: the distance measuring apparatus according to claim 15; and a collision determination unit which determines the possibility of collision between the host vehicle and the object based on the distance information.   17. The control device according to claim 16, further comprising: a control device that outputs a control signal that causes each wheel of the vehicle to generate a braking force when it is determined that there is a collision possibility between the vehicle and the object. In-vehicle camera system as described.   18. The on-vehicle according to claim 16, further comprising: an alarm device that issues an alarm to a driver of the host vehicle when it is determined that there is a collision possibility between the host vehicle and the object. Camera system.