JP2004354714A - Lens system for visible light/infrared light photography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens system for visible light/infrared light photography constituted to simultaneously perform photography with visible light and infrared light in a state where a subject at the same distance is brought into focus by spectrally splitting subject light made incident on a photographic lens and passing through a focus lens to the subject light in a visible light region and the subject light in an infrared light region by a color separation prism or the like, imaging each subject light by an imaging device for visible light and an imaging device for infrared light, and also adjusting the image forming position of the subject light in the infrared light region by a correction lens. <P>SOLUTION: In the lens system, the color separation prism P is arranged at the rearmost side of the photographic lens 10 designed for the visible light, and the subject light in the visible light region is transmitted through the prism P and made incident on the imaging device for the visible light DA, and the subject light in the infrared light region is reflected on the prism P and passes through a relay lens RLB including a diaphragm IB and the correction lens CL, and then it is made incident on the imaging device for the infrared light DB. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a visible light / infrared light photographing lens system, and more particularly to a visible light / infrared light photographing lens system capable of simultaneously photographing the same subject with visible light and infrared light.
[0002]
[Prior art]
When shooting with a television camera (for example, a CCTV camera) for monitoring or the like, shooting is performed with visible light in a bright environment such as daytime, and in a dark environment where a subject cannot be observed with visible light such as nighttime. In this case, imaging with infrared (near infrared) light is performed.
[0003]
Conventionally, there is a case where one camera shoots both visible light and infrared light, and the shooting lens attached to the camera body is also used without changing for visible light and infrared light. What is made known is known. For example, if a photographing lens designed for photographing with visible light is directly used for photographing with infrared light, there is a problem that axial chromatic aberration with infrared light increases. In particular, when a visible light shooting lens with a zoom function is used for infrared light, even if tracking adjustment (flange back adjustment) is performed, if the zoom magnification is changed, the focus will shift, and tracking adjustment (flange back adjustment) will be performed. ) Cannot be performed effectively.
[0004]
Therefore, when a photographing lens used for visible light is also used for photographing with infrared light, for example, by using a low-dispersion glass such as fluorite or ED glass for the lens, the wavelength of infrared light is optically measured. A method of reducing chromatic aberration to a region, a method of inserting an optical member (lens / prism) for correcting chromatic aberration into an optical system of a photographing lens, and the like are applied.
[0005]
Also, for example, under a slightly dark shooting condition such as in the evening, it is desirable to simultaneously perform shooting with infrared light that can clearly show the subject and shooting with visible light that can obtain color information of the subject. There are cases. However, when a single camera is used by switching between visible light and infrared light imaging, it is not possible to simultaneously perform visible light and infrared light imaging. For this reason, conventionally, there have been cases where two cameras, one for visible light and one for infrared light, shoot simultaneously. However, if two cameras are used, two lens operations such as focusing and zooming are performed at the same time, and the shooting distance (distance to a focused subject position (subject distance)) and the angle of view are adjusted. There was a problem that it required time and effort. Further, when two cameras are used, there is a problem that a parallax is generated between the cameras, and the angle of view of an image captured with visible light does not match the angle of view of an image captured with infrared light.
[0006]
On the other hand, in Japanese Patent Application Laid-Open No. H11-157, the subject light incident on the taking lens is divided by a half mirror, and one is taken as a subject light for visible light and the other is taken as a subject light for infrared light. An imaging device has been proposed. According to this, it is possible to make the angle of view of an image shot with visible light coincide with the angle of view of an image shot with infrared light.
[0007]
Also, using two cameras for visible light and infrared light, for example, the subject light from the subject to be photographed is divided into visible light and infrared light The angle of view of the video shot with the camera for visible light and the angle of view of the video shot with the camera for infrared light can be made to match by entering the camera lens for infrared light and the shooting lens of the camera for infrared light. It is possible.
[0008]
[Patent Document 1]
JP-A-2003-69865
[0009]
[Problems to be solved by the invention]
However, in Patent Literature 1, it is not assumed that photographing of visible light and infrared light is performed at the same time. Therefore, there is a problem in performing photographing of visible light and infrared light at the same time. That is, when an optical system such as a focus lens (group) or a zoom lens (group) is arranged at a stage preceding the half mirror, the wavelength characteristics of the optical system differ between the visible light region and the infrared light region. Therefore, if the focus lens and the zoom lens are set at a predetermined position, and the focus lens and the zoom lens are moved from the predetermined position, the visible light and the infrared There is a problem that the light shooting distances do not match. Further, in the cited document 1, since there is no means for individually adjusting the focus positions of the visible light and the infrared light, when the photographing distances of the visible light and the infrared light are different, it cannot be corrected.
[0010]
On the other hand, as described above, the subject light from the subject to be photographed is divided into visible light and infrared light subject light by a mirror or a prism, and then divided into visible light camera and infrared light camera photographing lenses, respectively. When the light is incident, the focus can be adjusted individually by the photographing lenses of the cameras, so that the subject at the same position can be focused. However, when two cameras are used, there is a problem in that it is necessary to perform two lens operations such as focusing and zooming at the same time and to operate so that the shooting distance and the angle of view coincide. In addition, there is a problem that the size of the entire apparatus is increased and the cost increases because two photographing lenses need to be used for the visible light camera and the infrared light camera. Further, when a mirror or a prism is arranged in front of the photographing lens, it is necessary to use a lens larger than the front lens of the photographing lens, so that the mirror or the prism becomes large, which also causes an increase in the size of the apparatus. In addition, there is a problem that the cost increases.
[0011]
The present invention has been made in view of such circumstances, and it is possible to easily photograph the same subject simultaneously with visible light and infrared light without the trouble of an operator, and to increase the size and cost of the apparatus. It is an object of the present invention to provide a visible light / infrared light photographing lens system capable of suppressing elevation.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is a visible light / infrared light photographing lens system that enables simultaneous photographing of the same subject with visible light and infrared light. A subject image formed by subject light in the first wavelength region, wherein one of the visible light region and the infrared light region is a first wavelength region, and the other wavelength region is a second wavelength region. First imaging means for imaging a subject, second imaging means for imaging a subject image formed by subject light in the second wavelength region, and first imaging means for imaging the subject with the first imaging means. An optical system that forms an image of the subject light on the imaging surface of the first imaging unit, the optical system including a focus lens that is movable in the optical axis direction in order to focus on a subject at a desired subject distance; Is shared with the optical system. A light splitting unit disposed behind the focus lens, wherein the light from the subject incident on the optical system is imaged by the first object light and a second image by the second imaging unit. A light splitting means for splitting into the subject light, and a relay optical system for forming an image of the second subject light again after being split by the light splitting means and forming an image by the action of the optical system, A relay optical system including a correction lens movable in an optical axis direction for adjusting an image forming position; a subject distance of a subject focused on an imaging surface of the first imaging unit; Correction lens control means for controlling the position of the correction lens based on the position of the focus lens so that the object distance of the object in focus with respect to the imaging surface of the imaging means is matched. There.
[0013]
The invention according to a second aspect is the invention according to the first aspect, further comprising a zoom lens movable in an optical axis direction to change a zoom magnification in front of the light splitting unit, and the correction lens The control means controls the position of the correction lens based on the position of the focus lens and the position of the zoom lens.
[0014]
A third aspect of the present invention is a lens system for photographing visible light and infrared light which enables simultaneous photographing of the same subject with visible light and infrared light. A first wavelength region in which one of the external light regions is a wavelength region, a second wavelength region in the other wavelength region, and a first image capturing a subject image formed by subject light in the first wavelength region. Imaging means, second imaging means for imaging a subject image formed by the subject light in the second wavelength region, and first object light for imaging the subject by the first imaging means. An optical system for forming an image on an imaging surface of the imaging means, wherein the optical system includes a focus lens movable in an optical axis direction in order to focus on a subject at a desired subject distance; And the focus lens A light splitting means disposed on a rear side of the light source, wherein the first light and the second light for imaging the object by the second imaging means. And a light splitting unit that guides the second subject light to an imaging surface of the second imaging unit; and a second light source that is split by the light splitting unit and forms an image by the action of the optical system. A relay optical system for forming an image of the subject light again, a subject distance of a subject that is in focus with respect to the imaging surface of the first imaging unit, and a focus with respect to the imaging surface of the second imaging unit. Control means for controlling the position of the image pickup surface of the second image pickup means based on the position of the focus lens such that the subject distance of the matching subject coincides.
[0015]
According to a fourth aspect of the present invention, in the first, second, or third aspect, the light splitting means converts the incident subject light into a visible light region subject light and an infrared light region subject light. In addition, it is a spectral means for spectrally dispersing light in a wavelength region.
[0016]
According to the present invention, since the subject distance of the subject that is in focus in imaging with visible light and the subject distance of the subject that is in focus in imaging with infrared light are made to match with a correction lens or the like, the visible light and the red It becomes possible to focus on the same subject at the same subject distance with external light and simultaneously shoot the same subject. In addition, since the control of the correction lens and the like is automatically controlled based on the position of the focus lens and the like, the operation of the operator is not required.
[0017]
Also, the light splitting means for splitting the subject light for visible light and the subject light for infrared light may be arranged behind the focus lens commonly used for photographing visible light and infrared light. Therefore, it is possible to suppress an increase in the size of the system and an increase in cost without increasing the size of the light splitting unit. Cost reduction can also be achieved by using a focus lens for both visible light and infrared light photography. In particular, a general photographing lens conventionally used as a configuration of an optical system other than the light splitting means by disposing the light splitting means at the end of the optical system of the subject light in the visible light region or the subject light in the infrared light region. Can be applied as it is, design is easy, and special manufacturing costs can be reduced.
[0018]
Furthermore, since one subject light split by the light splitting means is once formed into an image and then formed again on the image pickup surface of the image pickup device, and a correction lens or the like is arranged in an optical path between the light beams, an optical device such as a correction lens is used. A sufficient space for arranging components can be secured.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a lens system for photographing visible light and infrared light according to the present invention will be described in detail with reference to the accompanying drawings.
[0020]
FIG. 1 is a diagram showing an overall configuration of a lens system to which the present invention is applied. The lens system shown in the figure used for a surveillance television camera or the like is a system that can simultaneously photograph the same subject with visible light and infrared light (near infrared light). As shown in FIG. 1, the present lens system includes a lens device including an optical system (photographing lens) 10 and a control system 12, and an imaging device that captures an image of a subject by subject light in a visible light wavelength region (visible light region). A camera body 14 for visible light equipped with a device (CCD) DA, and a camera for infrared light equipped with an image sensor (CCD) DB for taking an image of a subject by subject light in a wavelength region of infrared light (infrared light region). And a main body 16. The photographing lens 10 in which various optical components are arranged in the lens barrel can be attached to and detached from the visible light camera body 14 and the infrared light camera body 16 by a predetermined mount.
[0021]
The taking lens 10 includes a main optical system through which both the subject light in the visible light region and the subject light in the infrared light region pass, and a sub optical system through which only the subject light in the infrared light region branched from the main optical system passes. It is composed of
[0022]
The main optical system includes a focus lens (group) FL, a zoom lens (group) ZL, a diaphragm (diaphragm mechanism) IA, a relay lens (group) RLA, and a color separation prism P in order from the object side along the optical axis O. Is arranged. An image sensor DA of the visible light camera body 14 is disposed downstream of the color separation prism P on the optical axis O.
[0023]
On the other hand, a relay lens (group) RLB is arranged in the sub-optical system along an optical axis O ′ substantially orthogonal to the optical axis O, and an aperture IB is arranged in a component of the relay lens RLB. An imaging device DB of the infrared camera body 16 is arranged at a stage subsequent to the relay lens RLB.
[0024]
The subject light in the visible light region among the subject light incident on the photographing lens 10 passes through the focus lens FL, the zoom lens ZL, the aperture IA, the relay lens RLA, and the color separation prism P of the main optical system in order, and becomes visible light. Incident on the imaging surface of the imaging element DA for use.
[0025]
On the other hand, the subject light in the infrared light region passes through the focus lens FL, the zoom lens ZL, the aperture IA, and the relay lens RLA of the main optical system in that order, and is thereafter reflected by the color separation prism P. Then, the light passes through the relay lens RLB of the sub optical system and is incident on the imaging surface of the imaging device DB for infrared light.
[0026]
In the following, the term “visible light optical system” refers to an optical system through which subject light in the visible light region passes, that is, an optical system that is a main optical system and has an optical path that passes through the color separation prism P. On the other hand, in the case of an infrared light optical system, an optical system through which subject light in the infrared light region passes, that is, an optical system that is a main optical system and reflects an optical path reflected by the color separation prism P, and an auxiliary optical system Shall be referred to.
[0027]
The focus lens FL is moved back and forth in the direction of the optical axis O by a focus motor FM, and is driven at the time of focus adjustment of the optical system for visible light and the optical system for infrared light. When the position of the focus lens FL changes, the imaging position of the visible light optical system with respect to the subject light in the visible light region causes the subject position (the imaging surface and the imaging surface) to be in focus with the imaging surface of the imaging device DA for visible light. In addition to the change in the distance to the conjugate object plane, the infrared light optical system focuses on the imaging surface of the infrared light imaging device DB due to the imaging effect of the infrared light optical system on the subject light in the infrared light region. The distance to the subject position changes. In the following description, a distance to a subject position in focus with respect to the imaging surface of the imaging device DA is referred to as a subject distance of the optical system for visible light, and a subject in focus with the imaging surface of the imaging device DB. The distance to the position is called a subject distance of the infrared light optical system.
[0028]
The zoom lens ZL is moved back and forth in the optical axis O direction by a zoom motor ZM, and is driven during zoom adjustment (adjustment of a focal length) of the optical system for visible light and the optical system for infrared light. You. The zoom lens ZL includes a variable power lens (group) and a correction lens (group), and these lenses are linked to each other in a predetermined positional relationship to change the zoom magnification (focal length) when the zoom magnification (focal length) is changed. Correction is performed so that the imaging positions of the subject light in the light region and the infrared light region do not change. That is, correction is performed so that the subject distance of the optical system for visible light and the optical system for infrared light does not change. However, with respect to the subject distance of the infrared light optical system, a change due to a change in the zoom magnification cannot be completely corrected, and is corrected by the correction lens CL as described later.
[0029]
The aperture IA is opened and closed by an aperture motor IMA, and is incident upon the aperture adjustment, that is, the subject light in the visible light region incident on the imaging surface of the imaging device DA and the imaging surface of the imaging device DB. Driven when adjusting the amount of subject light in the infrared light region.
[0030]
The relay lens RLA is a lens group that forms an image of the subject light in the visible light region and the subject light in the infrared light region, and a tracking lens (group) TL for tracking adjustment (flange back adjustment) disposed in a part thereof. Move back and forth in the optical axis O direction. The tracking lens TL is manually operated, for example, when performing tracking adjustment of the visible light optical system before the start of photographing, and the imaging position of the visible light optical system even when the zoom lens ZL is moved from the wide end to the tele end. (That is, the subject distance of the optical system for visible light) is set at a position that does not change. Although the tracking lens TL is manually operated in the system shown in the figure, it may be driven by a motor.
[0031]
The color separation prism P separates the incident subject light into visible light region subject light and near-infrared light region subject light on the mirror surface PM, transmits the visible light region subject light, and transmits the visible light region subject light. To reflect the subject light. Therefore, the subject light in the visible light region travels in the direction of the optical axis O as it is, and the subject light in the infrared light region travels in the direction of the optical axis O ′ substantially perpendicular to the optical axis O.
[0032]
FIG. 2 shows an example of the wavelength characteristics of the color separation prism P. As shown in the figure, subject light in a visible light region on the shorter wavelength side from about 700 nm is transmitted through the color separation prism P with a transmittance of about 90%, and red light on a longer wavelength side than about 700 nm is used. The subject light in the outside light area is reflected by the color separation prism P with a reflectance exceeding about 90%.
[0033]
The subject light incident on the taking lens 10 may be divided into visible light subject light and infrared light subject light using a dichroic mirror or a half mirror instead of the color separation prism P. However, unlike a color separation prism or a dichroic mirror that divides the subject light according to the wavelength region, when using a light dividing unit such as a half mirror that divides the light into a light beam having almost the same wavelength range, the light for visible light and the It is desirable that light in an unnecessary wavelength region be removed from the visible light subject light by a filter.
[0034]
When a light splitting unit such as a color separation prism P is arranged at the end of the optical system for visible light (main optical system) as in the present embodiment, the optical system for visible light excluding the light splitting unit is used. Can be designed to be exactly the same design as a television lens used in a three-color CCD camera. That is, when a single-color CCD is used as the image pickup device of the visible light camera main body 14 as shown in the figure, the RGB three-color separation prism used in the three-color CCD is not provided. Therefore, by using the optical system for visible light with the same configuration as the television lens used in the camera of the three-color CCD and using it in the camera of the single-color CCD, it is possible to create a space corresponding to the optical path of the RGB three-color separation prism. The color separation prism P of the present embodiment can be arranged in the space.
[0035]
The imaging device DA of the visible light camera body 14 photoelectrically converts the subject light in the visible light region formed on the imaging surface, and outputs an image of the subject as an electric signal. A required signal processing circuit is mounted on the visible light camera body 14, and a signal output from the image sensor DA is converted into a video signal by the signal processing circuit and output to an external device or the like.
[0036]
The relay lens RLB is a lens group that finally forms an image of the subject light in the infrared light region, and re-images the subject light in the infrared light region once formed by the imaging operation of the main optical system.
[0037]
That is, an infrared light region which is guided from the subject at a predetermined subject distance corresponding to the position of the focus lens FL to the sub optical system through the main optical system is formed by the main optical system. Assuming that the position is an image forming plane S shown in the sub optical system of FIG. 1, the relay lens RLB forms an image formed on the image forming plane S on the image pickup surface of the image pickup device DB.
[0038]
In addition, a correction lens (group) CL is disposed in a part of the relay lens RLB, and an aperture IB is disposed in a component of the relay lens RLB.
[0039]
The correction lens CL is moved back and forth in the direction of the optical axis O ′ by the correction motor CM, and is driven to follow a change in the position of the focus lens FL or the zoom lens ZL. That is, when the position of the correction lens CL changes, the image formation position of the subject light in the infrared light region changes and the subject distance of the optical system for infrared light changes, so by controlling the position of the correction lens CL The object distance of the optical system for infrared light is adjusted so as to coincide with the object distance of the optical system for visible light, that is, the object distance planned corresponding to the position of the focus lens FL. The details will be described later.
[0040]
The aperture IB is opened and closed by an aperture motor IMB. When the aperture of the infrared optical system is adjusted, that is, the amount of subject light in the infrared light area incident on the imaging surface of the image sensor DB. Driven when adjusting.
[0041]
The imaging device DB of the infrared light camera body 16 photoelectrically converts the subject light in the infrared light region formed on the imaging surface, and outputs an image of the subject as an electric signal. A required signal processing circuit is mounted on the infrared camera body 16, and a signal output from the image sensor DB is converted into a video signal by the signal processing circuit and output to an external device or the like.
[0042]
The control circuit 20 of the control system 12 detects the positions of the focus lens FL, the zoom lens ZL, the aperture IA, the aperture IB, and the correction lens CL using potentiometers FP, ZP, IPA, IPB, and CP, respectively, while detecting the focus motor FM. Then, the zoom motor ZM, the iris motors IMA and IMB, and the correction motor CM are driven to control the position (or operating speed) of each lens and aperture.
[0043]
For example, a command signal indicating a target movement position (or target movement speed) of the focus lens FL or the zoom lens ZL is given to the control circuit 20 from the controller based on an operator's focus operation or zoom operation by a controller (not shown). The control circuit 20 drives and controls the focus motor FM and the zoom motor ZM based on the given command signal, and controls the position or speed of the focus lens FL and the zoom lens ZL.
[0044]
Further, for example, in the visible light camera body 14 and the infrared light camera body 16, an aperture value at which an image captured by the imaging elements DA and DB has appropriate brightness is determined, and the aperture value is determined. A command signal instructing the setting of is set from each of the camera bodies 14 and 16 to the control circuit 20. The control circuit 20 drives the iris motors IMA and IMB based on these command signals, and controls the positions of the apertures IA and IB.
[0045]
Here, when photographing with infrared light, a subject is often irradiated with infrared light using an infrared light illuminating device. Therefore, the intensity of the subject light in the infrared light region is often higher than the intensity of the subject light in the visible light region. In consideration of such circumstances, the light amount of the subject light in the infrared light region can be adjusted by the aperture IB in addition to the aperture IA. For example, the aperture IA is controlled by an aperture value specified by a command signal from the visible light camera body 14, and is set to a position where the brightness of an image captured by subject light in the visible light region is appropriate. On the other hand, for subject light in the infrared light region, there is a high possibility that the light amount will be excessive only by adjusting the light amount of the aperture IA alone, so that the aperture IB is designated by a command signal from the infrared light camera body 16. Control by value. At this time, since the aperture value indicated by the command signal from the infrared light camera body 16 is a value to be satisfied by both the aperture IA and the aperture IB, the position of the aperture IB is considered in consideration of the position of the aperture IA. Control.
[0046]
It is not always necessary to provide the aperture IB. Further, the ND filter switching mechanism, or the liquid crystal variable, is narrowed down to at least one of a position where the subject light in the visible light region and a position where the subject light in the infrared light region passes after the color separation prism P. A light amount adjustment mechanism such as a transmission mechanism may be provided.
[0047]
Further, the control of the focus lens FL, the zoom lens ZL, and the apertures IA and IB may be performed by a method other than those described above.
[0048]
On the other hand, the control of the correction lens CL is performed by referring to the correction data stored in the memory 22 in advance and driving the correction motor CM so that the correction lens CL is at a position read by the correction data.
[0049]
Here, the object distance of the optical system for visible light is equal to the object distance planned corresponding to the position of the focus lens FL, and the tracking adjustment is performed in advance by the tracking lens TLA so that the zoom lens can be used. Even if the position of ZL is changed, the subject distance does not change. On the other hand, the subject distance of the infrared light optical system is designed so that optical components (such as the focus lens FL and the zoom lens ZL) commonly used with the visible light optical system are adapted to the subject light in the visible light region. Therefore, the subject distance does not match the subject distance (that is, the subject distance of the optical system for visible light) corresponding to the position of the focus lens FL, and the shift amount also differs depending on the position of the focus lens FL. Further, when the position of the zoom lens ZL is changed, the subject distance of the optical system for infrared light changes, and the amount of the change also differs depending on the position of the zoom lens ZL.
[0050]
Therefore, the subject distance of the infrared light optical system is set to match the planned subject distance corresponding to the position of the focus lens FL (that is, the subject distance of the visible light optical system), and the zoom lens ZL is used. The position of the correction lens CL is controlled so that the object distance of the infrared light optical system does not change even if the position is changed, and the object distance of the infrared light optical system is corrected. The position of the correction lens CL for correcting the subject distance of the infrared light optical system is calculated in advance by a theoretical operation or the like for each position of the focus lens FL and the zoom lens ZL, and is stored in the memory 22 as correction data. The position of the correction lens CL at the time of shooting is determined by referring to the correction data.
[0051]
FIG. 3 is a diagram illustrating an example of the correction data as a data table, and FIG. 4 is a diagram illustrating the correction data as a three-dimensional graph. As can be seen from these figures, the correction data is obtained by associating the correction amount from a predetermined reference position of the correction lens CL with each position of the focus lens FL and the zoom lens ZL, and is read from the potentiometers FP, ZP. The current position of the focus lens FL and the zoom lens ZL, or the target position of the focus lens FL and the zoom lens ZL to be set based on the command signal, is set as the position of the focus lens FL and the zoom lens ZL in the correction data, and their positions are set. By reading the correction amount of the correction lens CL corresponding to the correction data from the correction data, the correction amount from the reference position of the correction lens CL to match the subject distance of the optical system for infrared light with the subject distance of the optical system for visible light You can get to know.
[0052]
When the control circuit 20 displaces the focus lens FL or the zoom lens ZL based on the command signal, the control circuit 20 sets the current position of the focus lens FL and the zoom lens ZL read from the potentiometers FP and ZP or the setting based on the command signal. The correction amount of the correction lens CL with respect to the target positions of the focus lens FL and the zoom lens ZL to be read is read from the correction data as described above. Then, the subject distance of the optical system for infrared light is made to coincide with the subject distance of the optical system for visible light by displacing the correction lens CL from the predetermined reference position by the correction amount read from the correction data. As a result, the position of the subject focused by the optical system for visible light coincides with the position of the subject focused by the optical system for infrared light, and the image by the visible light and the infrared light focused on the same subject The image and the image can be simultaneously photographed by the imaging devices DA and DB.
[0053]
Further, since the zoom lens ZL is shared by the optical system for visible light and the optical system for infrared light, the zoom magnification (angle of view) for the visible light image and the infrared light image is almost the same. However, the shooting angle of view does not necessarily need to match, and it is sufficient for operation if the center of the shooting angle of view almost matches the shooting position, and at least this condition is satisfied. Further, the angle of view for photographing with visible light and the angle of view for photographing with infrared light can be intentionally made different from each other depending on the arrangement and configuration of the relay lens RLB, or the image size of the image sensor DA and the image sensor DB can be reduced. Can be made to coincide with each other when the shooting angles are different. Further, a variable magnification system lens may be arranged in the sub optical system so that the sub-optical system can be driven by a motor or the like, so that the angle of view for photographing with infrared light can be changed to a desired zoom magnification.
[0054]
In the case of the correction data in the format shown in FIGS. 3 and 4, the correction amount of the correction lens CL is associated with the discrete positions of the focus lens FL and the zoom lens ZL, and the focus to be obtained is determined. In some cases, the correction amount of the correction lens CL with respect to the positions of the lens FL and the zoom lens ZL cannot be directly read from the correction data. In such a case, for example, the amount of correction of the correction lens CL with respect to desired positions of the focus lens FL and the zoom lens ZL can be obtained by interpolating data by an interpolation operation.
[0055]
In addition, the correction data indicates data that provides an optimum correction amount for subject light having a specific wavelength (main wavelength) in the infrared light region. For example, when performing imaging with infrared light, May illuminate a subject with an infrared light illuminator. In this case, it is preferable to use correction data corresponding to the main wavelength (the wavelength of the maximum intensity) of the illuminating light. For example, if the main wavelength of the illuminating light is 950 nm, it is preferable to use correction data that provides an optimal correction amount for the 950 nm subject light. Further, several types of correction data having different main wavelengths may be stored in the memory 22 so that the user can appropriately select correction data to be actually referred to according to the main wavelength of the illumination light or the like, or The wavelength may be detected by a sensor, and optimum correction data may be selected in accordance with the wavelength.
[0056]
Further, the method of obtaining the correction amount of the correction lens CL is not limited to the above-described method, and another method such as obtaining the correction amount by calculation using a mathematical expression may be used.
[0057]
In addition, since the subject distance of the optical system for infrared light accurately changes depending on the position of the stop IB, the correction amount of the correction lens CL is determined by the position of the stop IB in addition to the positions of the focus lens FL and the zoom lens ZL. Is preferably determined in consideration of the following.
[0058]
Further, the reference position of the correction lens CL may need to be changed according to the position of the tracking lens TL in the optical system for visible light. In this case, for example, the control circuit 20 may change the position of the tracking lens TL. This can be dealt with by detecting the position of the tracking lens TL and adjusting the reference position appropriate for the position of the tracking lens TL using a data table stored in the memory 22 in advance.
[0059]
As described above, in the above-described embodiment, the subject distance of the infrared light optical system is corrected by the correction lens CL according to the positions of the focus lens FL and the zoom lens ZL. May be corrected, and the subject distance of the visible light optical system may be corrected according to the positions of the focus lens FL and the zoom lens ZL. That is, the configuration and control of the optical system for visible light in the above embodiment are applied as the configuration and control of the optical system for infrared light, and the configuration and control of the optical system for infrared light in the above embodiment are changed to visible light. May be applied as the configuration and control of the optical system for use.
[0060]
In the above-described embodiment, the color separation prism P transmits the subject light in the visible light region and reflects the subject light in the infrared light region.
[0061]
Further, in the above-described embodiment, the case where the present invention is applied to the photographing lens provided with the focus lens FL and the zoom lens ZL has been described. However, the fixed focal length photographing lens not provided with the zoom lens ZL, that is, the single focus lens The present invention can be similarly applied to the above.
[0062]
In the above embodiment, the color separation prism P is arranged at the end of the main optical system, but may be arranged at another position in the main optical system.
[0063]
Further, in the above embodiment, the object distance of the optical system for infrared light is corrected by moving the position of the correction lens CL, but instead of moving the position of the correction lens CL, the imaging surface of the image sensor DB is moved. By moving the position, the subject distance of the infrared light optical system can be corrected. In addition to directly moving the imaging device DB as a method of moving the position of the imaging surface of the imaging device DB, the mount portion where the photographing lens 10 and the infrared light camera body 16 are mounted is moved, and the photographing lens 10 is moved. The entire infrared light camera body 16 may be moved.
[0064]
Further, in the above-described embodiment, in the infrared light optical system, since the subject in the infrared light region is reflected by the mirror surface PM by the decomposing prism P, the image captured by the image sensor DB is an inverted image. In order to solve this, the image may be electrically inverted in the signal processing after the image pickup, or may be optically inverted. FIG. 5 is a diagram showing the configuration of the photographing lens in that case. In FIG. 5, components having the same or similar functions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The configuration of a visible light optical system (main optical system) of the photographing lens 10 shown in FIG. 5 is exactly the same as that of FIG. 1, and the configuration of an infrared light optical system (sub optical system) is the same as that of FIG. different. That is, in the infrared light optical system shown in FIG. 5, a subject in the infrared light region that is reflected by the mirror surface PM of the color separation prism P and travels along the optical axis O ′ is subsequently moved by the mirror M to the optical axis O ′. The light is reflected in a direction substantially perpendicular to the optical axis O ″. The light then passes through the relay lens RLB on the optical axis O ″ and enters the image pickup surface of the image pickup device DB of the infrared camera body 16. . As described above, by reflecting the subject light in the infrared light region by the mirror M arranged in the infrared light optical system, the image captured by the image pickup device DB can be optically prevented from being an inverted image. Is done.
[0065]
Further, the reflection direction of the mirror M shown in FIG. 5 may be set not to the backward direction of the photographing lens but to the front direction as shown in FIG. 6, so that the photographing lens 10 becomes compact. There is an advantage that it becomes.
[0066]
【The invention's effect】
As described above, according to the visible light / infrared light photographing lens system according to the present invention, the subject distance of the subject that is in focus by imaging with visible light and the subject that is in focus by imaging with infrared light Since the distance is made to coincide with a correction lens or the like, it becomes possible to focus on the same subject at the same subject distance with visible light and infrared light and simultaneously photograph the same subject. In addition, since the control of the correction lens and the like is automatically controlled based on the position of the focus lens and the like, the operation of the operator is not required.
[0067]
Also, the light splitting means for splitting the subject light for visible light and the subject light for infrared light may be arranged behind the focus lens commonly used for photographing visible light and infrared light. Therefore, it is possible to suppress an increase in the size of the system and an increase in cost without increasing the size of the light splitting unit. Cost reduction can also be achieved by using a focus lens for both visible light and infrared light photography. In particular, a general photographing lens conventionally used as a configuration of an optical system other than the light splitting means by disposing the light splitting means at the end of the optical system of the subject light in the visible light region or the subject light in the infrared light region. Can be applied as it is, design is easy, and special manufacturing costs can be reduced.
[0068]
Furthermore, since one subject light split by the light splitting means is once formed into an image and then formed again on the image pickup surface of the image pickup device, and a correction lens or the like is arranged in an optical path between the light beams, an optical device such as a correction lens is used. A sufficient space for arranging components can be secured.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a lens system to which the present invention is applied.
FIG. 2 is a diagram illustrating an example of a wavelength characteristic of a color separation prism.
FIG. 3 is a diagram illustrating an example of correction data of a correction lens as a data table.
FIG. 4 is a diagram showing the correction data of FIG. 3 in a three-dimensional graph.
FIG. 5 is a diagram illustrating a configuration of another embodiment of a photographing lens.
FIG. 6 is a diagram showing a configuration of another embodiment of a photographing lens.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Optical system (photographing lens), 12 ... Control system, 14 ... Visible light camera main body, 16 ... Infrared light camera main body, DA, DB ... Image sensor, FL ... Focus lens, ZL ... Zoom lens, P ... Color separation prism, IA, IB stop, RLA, RLB relay motor, FM focus motor, ZM zoom motor, IMA, IMB stop motor, TL tracking lens, CL correction lens, CM correction Motor, 20 control circuit, 22 memory

Claims (4)

A visible light / infrared light photographing lens system that enables simultaneous photographing of the same subject with visible light and infrared light,
One of the visible light region and the infrared light region is defined as a first wavelength region, the other wavelength region is defined as a second wavelength region, and a subject image formed by subject light of the first wavelength region is formed. First imaging means for imaging,
Second imaging means for imaging a subject image formed by subject light in the second wavelength region;
An optical system that forms a first object light for imaging an object by the first imaging unit on an imaging surface of the first imaging unit, and focuses on an object at a desired object distance. An optical system having a focus lens movable in the optical axis direction,
A light splitting unit that is disposed on the optical system and is disposed behind the focus lens, wherein the subject light incident on the optical system is divided by the first subject light and the second imaging unit. Light splitting means for splitting the light into a second object light for imaging the object,
A relay optical system for re-imaging the second subject light after being split by the light splitting means and forming an image by the action of the optical system, wherein an optical axis direction is used for adjusting an image forming position; A relay optical system with a correction lens that can move
The focus lens is moved so that the subject distance of the subject that is in focus with respect to the imaging plane of the first imaging means and the subject distance of the subject that is in focus with respect to the imaging plane of the second imaging means match. Correction lens control means for controlling the position of the correction lens based on the position,
A lens system for photographing visible light and infrared light, comprising: A zoom lens movable in an optical axis direction to change a zoom magnification in front of the light splitting unit; and the correction lens control unit performs the correction based on the position of the focus lens and the position of the zoom lens. 2. The lens system according to claim 1, wherein the position of the lens is controlled. A visible light / infrared light photographing lens system that enables simultaneous photographing of the same subject with visible light and infrared light,
One of the visible light region and the infrared light region is defined as a first wavelength region, the other wavelength region is defined as a second wavelength region, and a subject image formed by subject light of the first wavelength region is formed. First imaging means for imaging,
Second imaging means for imaging a subject image formed by subject light in the second wavelength region;
An optical system that forms a first object light for imaging an object by the first imaging unit on an imaging surface of the first imaging unit, and focuses on an object at a desired object distance. An optical system having a focus lens movable in the optical axis direction,
A light splitting unit that is disposed on the optical system and is disposed behind the focus lens, wherein the subject light incident on the optical system is divided by the first subject light and the second imaging unit. A light splitting unit that splits the second subject light into a second subject light for imaging the subject and guides the second subject light to an imaging surface of the second imaging unit;
A relay optical system for re-imaging the second subject light after being split by the light splitting means and forming an image by the action of the optical system;
The focus lens is moved so that the subject distance of the subject that is in focus with respect to the imaging plane of the first imaging means and the subject distance of the subject that is in focus with respect to the imaging plane of the second imaging means match. Control means for controlling the position of the imaging surface of the second imaging means based on the position;
A lens system for photographing visible light and infrared light, comprising: 4. The visible light according to claim 1, wherein the light splitting means is a spectral means for splitting incident subject light into subject light in a visible light region and subject light in an infrared light region in a wavelength region. Light and infrared light imaging lens system.

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