JP2014006110A - Laser radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser radar capable of highly accurately measuring a distance to an object by reducing noise while attaining a low cost.SOLUTION: A horizontal width is enlarged in a spot image B condensed on a light reception surface D of a photodetector PD by performing reshaping with the use of a reduction relay optical system ROS. Thus, an area occupied by a spot image on the light reception surface D is increased by the portion of a region R indicated by hatching. Consequently, the risk of receiving unnecessary light is reduced to thereby obtain an excellent S/N ratio.

Description

  The present invention relates to a laser radar that detects an object by irradiating a laser beam.

  As a device for measuring the distance to the object, a light projecting optical system including a laser light source that emits laser light toward the object and a light receiving optical system that receives the reflected light of the laser light that hits the object are used. Laser radars are known (see, for example, Patent Documents 1 and 2).

  In such a laser radar, if the laser light source emits light in a pulse shape for a very short time, for example, about 10 ns, and the laser light is emitted toward the object through the light projecting optical system, the emitted laser light is instantly emitted. And is received by the light receiving element via the light receiving optical system. Here, the time difference between the emission and reception of the laser beam is the time for the laser beam to reciprocate the distance to the object, so that the distance to the object can be obtained by multiplying this time difference by the speed of light and dividing by 2. It becomes.

  By the way, for example, in the case of an on-vehicle laser radar that is assumed to be used outdoors, the S / N ratio is deteriorated by sunlight other than the reflected light of the laser light irradiated by itself, headlights of oncoming vehicles, and the like. Furthermore, since the reflected light from the object is inversely proportional to the square of the distance, if the object has a low reflectance, the reflected light that can be received by the laser radar is reduced, and the measurable distance is reduced. On the other hand, if the laser output is increased, more reflected light can be obtained. However, in consideration of safety, there is a limit to the increase in laser output. Except for this, a method for improving the SN ratio is required.

  Further, since the on-vehicle laser radar is used for the purpose of detecting an obstacle in advance and optimally braking the vehicle, it is required to detect the obstacle with a wide-angle visual field in the horizontal direction. However, having a wide field of view in the light receiving optical system is not preferable because it is easily affected by ambient light and the SN ratio is lowered.

JP 2010-197341 A Japanese Patent Laid-Open No. 2003-130954 Japanese Patent Laid-Open No. 03-175390 JP 2001-194458 A

  On the other hand, Patent Document 3 discloses a technique for scanning light and received light using the same reflection scanning optical system. According to such a technique, by using the same reflection scanning optical system, the light receiving range of the light receiving element can be narrowed in the scanning direction. That is, by narrowing the visual field in the horizontal direction, it is possible to receive only a light beam close to the light projecting direction, so that a configuration resistant to disturbance light can be obtained. On the other hand, even if the reflected light received by the light receiving element has a narrow angle in the scanning direction, scanning in the same direction enables detection with a wide field of view.

  Here, in the case of a vehicle-mounted laser radar, the resolution in the horizontal direction is usually increased as shown in Patent Document 4. This is because detection in the horizontal direction is important for detecting obstacles in the traveling direction because the traveling direction of the vehicle is limited to straight or left and right. On the other hand, the vertical resolution need not be as strict as the horizontal direction. Therefore, it is preferable to use a laser beam having a vertically long cross section. When the reflected light of the laser beam emitted by such a vertically long beam is received by a rotationally symmetric lens, a vertically long image is formed on the light receiving surface of a photodiode as a light receiving element. However, the provision of the area sensor as in Patent Document 4 causes an increase in cost compared to a general general-purpose photodiode.

  In the case of a general-purpose photodiode, a light receiving surface is often square or circular. Therefore, when a vertically long image of the laser beam reflected from the object is formed on the light receiving portion of the photodiode, in order to fit the entire image in the light receiving portion, at least the same size as the vertical dimension of the formed spot image. It is necessary to use the light receiving section. For this reason, the horizontal dimension of the spot image is small in the lateral direction of the light receiving surface, and a region where no spot image is formed is generated on the light receiving surface, and unnecessary light that becomes noise other than measurement light is incident on this region. The light is received and the S / N is deteriorated. On the other hand, the S / N ratio can be increased by making the shape of the light receiving surface of the photodiode close to the same shape as the spot image to be imaged, but the cost increases because it becomes a custom photodiode instead. Resulting in.

  The present invention has been made in view of the above-described problems of the prior art. Even when the spot image shape of the emitted laser light and the light receiving surface shape of the light receiving element are different, the noise is reduced while being low in cost. An object of the present invention is to provide a laser radar capable of ensuring a S / N ratio and measuring a distance to an object with high accuracy.

The laser radar according to claim 1 scans and projects a laser light source, a collimating lens that converts divergent light from the laser light source into parallel light, and laser light collimated by the collimating lens onto a target region. A light projecting optical system including one reflection member;
A second reflecting member that reflects the reflected light from the target area that has been scanned and projected, and a reduction that includes a plurality of lenses for shaping the reflected light from the target area that is reflected by the second reflecting member Relay optics,
A light receiving optical system including a light receiving lens that condenses the light shaped by the reduction relay optical system on a light receiving surface of a light receiving element,
The cross section of the light beam projected from the light projecting optical system has a larger spread angle in the vertical direction than in the horizontal direction, and the reduction relay optical system satisfies the following expression.
mv <mh (1)
mh> 1 (2)
However,
mv: angular magnification in the vertical direction of the reduction relay optical system mh: angular magnification in the horizontal direction of the reduction relay optical system

  In the laser radar of the present invention, the cross-sectional shape of the projected laser beam on the object side is vertically long. That is, the cross section of the light beam projected from the light projecting optical system has a larger spread angle in the vertical direction than in the horizontal direction. For this reason, if the light is received on the light receiving element using a rotationally symmetric light receiving optical system, the image also becomes vertically long. When a general-purpose light receiving element is used, the shape of the light receiving surface and the image of the spot image to be formed are mismatched. And the background light increases, resulting in a deterioration of the S / N ratio. According to the present invention, a reduction relay optical system having a larger angular magnification in the horizontal direction than the angular magnification in the vertical direction that satisfies the expressions (1) and (2) is disposed in front of the light receiving lens. By changing the ratio of the spot shape (horizontal width / vertical dimension) of the reflected light imaged on the top and shaping it so as to improve the ratio of the spot area to the light receiving surface area according to the light receiving surface of the light receiving element It is possible to achieve both cost reduction and highly accurate detection.

  FIG. 1 is an enlarged view of the light receiving surface D of the light receiving element. Here, the spot image A collected without shaping of the reduction relay optical system is shown by a dotted line, and the spot image B collected by shaping by the reduction relay optical system of the present invention is shown by a solid line. However, the Y direction is the vertical direction, and the X direction is the horizontal direction. As is clear from FIG. 1, the spot image B collected by shaping with the reduction relay optical system of the present invention is applied to the spot image A collected without shaping of the reduction relay optical system. The vertical dimension is substantially matched with the corresponding vertical dimension on the light receiving surface D of the light receiving element. As a result, the area occupied by the spot image on the light receiving surface D is increased by the area R indicated by hatching, so that the possibility of receiving unnecessary light is reduced and the S / N ratio can be improved.

The laser radar according to claim 2 is characterized in that, in the invention according to claim 1, the following equation is satisfied.
0.17 <mv / mh <0.70 (3)

  Expression (3) is an expression for determining a ratio of angular magnifications in the horizontal direction and the vertical direction of the reduction relay optical system. When the value of the formula (3) exceeds the lower limit, it is preferable because the horizontal magnification does not become too large and the vertical viewing angle does not spread too much. In addition, the angular magnification in the horizontal direction is inevitably reduced, and the error sensitivity of the reduction relay optical system is reduced. On the other hand, if the value of the expression (3) is less than the upper limit, the effect of using the reduction relay optical system can be made sufficient, thereby eliminating the influence of unnecessary light and improving the S / N ratio. .

  The laser radar according to claim 3 is the invention according to claim 1 or 2, wherein the reduction relay optical system is a Kepler type at least in a horizontal section.

  When the reduction relay optical system has a horizontal cross section and is a Kepler type, it is possible to insert a slit to prevent disturbance light in the vicinity of the focal point inside the reduction relay optical system. The influence can be reduced.

  According to a fourth aspect of the present invention, there is provided the laser radar according to the first or second aspect, wherein the reduction relay optical system is a Galileo type at least in a horizontal section.

  When the reduction relay optical system is a Galileo type, the length of the reduction relay optical system in the optical axis direction can be shortened, and as a result, the light receiving optical system can be shortened. In addition, in the case of the two-lens configuration, the positive lens and the negative lens configuration make it possible to cancel the influence of the change in the refractive index of the resin even in an environment with a large temperature change in which the vehicle-mounted laser radar is used. A lens can be used, and the cost can be reduced.

  According to a fifth aspect of the present invention, in the laser radar according to any one of the first to fourth aspects, a band pass filter is disposed between the reduction relay optical system and the light receiving lens.

  A band-pass filter that allows light in a specific wavelength band to pass through interference is effective in reducing the influence of background light when used in the laser radar. Generally, it is known that the transmission band shifts to the short wavelength side as the incident angle increases. Therefore, in order to narrow the transmission band without losing the light having the laser oscillation wavelength, it is required to insert the laser beam into a parallel light beam as much as possible. Therefore, in the light receiving optical system, insertion after the second reflecting member as the scanning optical system is effective for narrowing the transmission band of the band pass filter. However, immediately after the second reflecting member, a band-pass filter having the same size as the received light beam is required, which leads to an increase in the size of the laser radar. Therefore, by arranging a band-pass filter between the reduction relay optical system and the light-receiving lens, it is possible to suppress an increase in incident angle, and it is possible to reduce the size of the band-pass filter and reduce the size of the laser radar. And cost reduction.

  A laser radar according to a sixth aspect of the invention is characterized in that, in the invention according to any one of the first to fifth aspects, the first reflecting member and the second reflecting member are common.

  If the first reflecting member and the second reflecting member are common, it is not necessary to synchronize rotation when separate members are used, and the size of the laser radar can be reduced.

  The laser radar according to claim 7 is the invention according to any one of claims 1 to 6, wherein the first reflecting member and the second reflecting member are rotatable about a rotation axis along a vertical direction. A polygon mirror having a plurality of reflecting surfaces on its side surface, wherein the angles of the reflecting surfaces with respect to the rotation axis are different from each other.

  As a result, each time the laser beam is reflected by the reflecting surface having a different angle, a different position can be scanned in the vertical direction of the screen, so that an obstacle can be detected with a wide field of view without increasing the light receiving surface of the light receiving element. .

  The laser radar according to an eighth aspect of the present invention is the invention according to any one of the first to seventh aspects, wherein the laser radar is for vehicle use. The laser radar of the present invention is suitable for in-vehicle use.

  According to the present invention, even when the spot image shape of the emitted laser beam and the light receiving surface shape of the light receiving element are different, the noise is reduced and the S / N ratio is ensured with high accuracy while the cost is low. A laser radar capable of measuring a distance to an object can be provided.

It is a figure which expands and shows the light-receiving surface D of a light receiving element. It is the schematic which shows the state which mounted the laser radar concerning this Embodiment in the vehicle. It is a schematic block diagram of the laser radar LR concerning this Embodiment. It is a figure which shows the screen corresponding to the object area | region scanned with the laser radar LR. 2 is a cross-sectional view of a reduction relay optical system and a light receiving lens of Example 1. FIG. FIG. 6 is a cross-sectional view of a reduction relay optical system and a light receiving lens of Example 2.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 2 is a schematic diagram showing a state in which the laser radar according to the present embodiment is mounted on a vehicle. The laser radar LR of the present embodiment is provided behind the front window 1a of the vehicle 1 or behind the front grill 1b.

  3A and 3B are schematic configuration diagrams of the laser radar LR according to the present embodiment. FIG. 3A is a diagram viewed along the horizontal direction, and FIG. 3B is a diagram viewed along the vertical direction. Here, the optical axis direction of the laser radar LR is taken as the Z direction, the vertical direction perpendicular to the Z direction is taken as the Y direction, and the horizontal direction perpendicular to the Z direction is taken as the X direction. The laser radar LR includes, for example, a semiconductor laser LD that emits a light beam having a longest wavelength in the operating temperature range of about 900 nm, a collimator lens CL that converts divergent light from the semiconductor laser LD into parallel light, and a collimator lens CL. The parallel laser beam (shown by the dotted line) is scanned and projected toward the object OBJ side (FIG. 2) by the rotating reflecting surface, and the reflected light from the scanned object OBJ is reflected. Polygon mirror (here, the first reflecting member and the second reflecting member) PM, a reduction relay optical system ROS that transmits and shapes the reflected light from the object OBJ reflected by the polygon mirror PM, and a predetermined band A bandpass filter BF that transmits light, a light receiving lens L3 that collects light transmitted through the reduction relay optical system ROS and the bandpass filter BF, and light reception Having a light receiving element PD for receiving the condensed light reflected by the lens L3.

  Here, a light projecting optical system is constituted by the semiconductor laser LD, the collimating lens CL, and the polygon mirror PM, and light is received by the polygon mirror PM, the reduction relay optical system ROS, the band pass filter BF, and the light receiving lens L3. Configure the optical system. The polygon mirror PM has a plurality of reflection surfaces PM1 to PM4 on its side surface, and each reflection surface PM1 to PM4 is slightly inclined at a different angle with respect to the rotation axis O along the vertical direction.

  The reflection surface for performing scanning projection is not limited to a polygon mirror, and a galvano mirror that reciprocally swings, a MEMS (Micro Electro Mechanical System) mirror, a DMD (Digital Mirror Device), or the like may be used.

The reduction relay optical system ROS satisfies the following expression.
mv <mh (1)
mh> 1 (2)
However,
mv: Angular magnification in the vertical direction of the reduction relay optical system mh: Angular magnification in the horizontal direction of the reduction relay optical system

  Specifically, the reduction relay optical system ROS includes a first lens L1 and a second lens L2. When the first lens L1 and the second lens L2 are viewed in the cross section of FIG. 3B, at least one of the optical surfaces is curved, and when viewed in the cross section of FIG. It is drawn as a straight line orthogonal to In other words, the reduction relay optical system ROS transmits as it is in the Y-direction section, refracts in the X-direction section, and passes through a rotationally symmetrical light receiving lens with the reduction relay optical system ROS, thereby increasing the horizontal image height. Yes. In the schematic diagram shown in FIG. 1, the image on the light receiving surface D is enlarged only in the horizontal direction with respect to a vertically long projection spot.

  Next, the ranging operation of the laser radar LR shown in FIG. 3 will be described. The divergent light emitted intermittently in pulses from the semiconductor laser LD has a larger spread angle in the vertical direction than in the horizontal direction. That is, it is a vertically long cross section. This laser light is converted into a parallel light beam by the collimator lens CL, and scanned and projected to the object OBJ side through the rotating polygon mirror PM. The divergent light from the semiconductor laser LD is emitted synchronously when the reflection surface of the polygon mirror PM is within a predetermined angle range with respect to the collimated light beam collimated, and is not emitted when the reflection surface is switched.

  FIG. 4 is a diagram showing a state in which the laser beam (shown by hatching) emitted on the screen G that is a detection range of the laser radar LR is scanned with the rotation of the polygon mirror PM. The reflection surfaces PM1 to PM4 of the polygon mirror PM are inclined at different angles with respect to the rotation axis O, and the laser light is sequentially reflected by the reflection surfaces PM1 to PM4 facing each other. First, the laser light reflected by the reflecting surface PM1 is scanned from left to right in the horizontal direction in the uppermost region LN1 of the screen G in accordance with the rotation of the polygon mirror PM. Next, the laser beam reflected by the reflecting surface PM2 is scanned from the left to the right in the second region LN2 from the top of the screen G in accordance with the rotation of the polygon mirror PM. Next, the laser beam reflected by the reflecting surface PM3 is scanned from the left to the right in the horizontal direction in the third region LN3 from the top of the screen G according to the rotation of the polygon mirror PM. Next, the laser beam reflected by the reflecting surface PM4 is scanned from left to right in the horizontal direction in the lowermost region LN4 of the screen G in accordance with the rotation of the polygon mirror PM. Thereby, the scanning of one screen is completed. Then, after the polygon mirror PM rotates once, if the reflection surface PM1 returns, scanning from the top of the screen G is repeated again.

  In FIG. 3, the laser beam reflected by the object OBJ out of the scanned light beam is incident on the polygon mirror PM and reflected again, and is shaped through the reduction relay optical system ROS. More specifically, the shaping is performed so that the ratio of the (horizontal width / vertical height) ratio of the spot image condensed on the light receiving surface D of the light receiving element PD is increased. Thereafter, the shaped light beam passes through the band-pass filter BF, and after unnecessary light is excluded, it is condensed by the light receiving lens L3 and detected by the light receiving surface of the light receiving element PD.

  According to the present embodiment, as shown in FIG. 1, the spot image B focused on the light receiving surface D of the light receiving element PD after being shaped by the reduction relay optical system ROS has a wide width in the horizontal direction. As a result, the area occupied by the spot image on the light receiving surface D is increased by the area R indicated by hatching, so that the background light causing noise is reduced and the S / N ratio can be improved. is there.

(Example)
Next, examples suitable for the above-described embodiment will be described. However, the present invention is not limited to the following examples. The meaning of each symbol in the embodiment is as follows.
rx: radius of curvature (mm) of the refracting surface in the X-direction cross section
ry: curvature radius (mm) of the refracting surface in the Y-direction cross section
d: Distance between shaft upper surfaces (mm)
nd: refractive index of lens material at d-line at room temperature vd: Abbe number of lens material

  In each example, the surface indicated by “*” after each surface number is an aspheric surface, and the aspheric surface has an origin at the apex of the surface and a Z axis in the optical axis direction. The height in the direction perpendicular to the optical axis is h, and is expressed by the following “Equation 1”.

ただし、
Ａｉ：ｉ次の非球面係数
ｒ ：曲率半径（ｒｘ、ｒｙ）
Ｋ ：円錐定数
である。

However,
Ai: i-order aspherical coefficient r: radius of curvature (rx, ry)
K: Conical constant.

In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is represented using E (for example, 2.5e−002). The surface number of the lens data was given in order with the object side of the first lens as one surface. In addition, the unit of the numerical value showing the length as described in an Example shall be mm. Further, in the following embodiments, the parallel plate bandpass filter BF is omitted, but it is preferably disposed between the surface number 4 and the surface number 5, and since it is a parallel plate, the surface number 4 and the surface It suffices that the intervals of the number 5 are arranged so as to be equivalent to the following embodiments in terms of air.

Example 1
Table 1 shows lens data of the reduction relay optical system and the light receiving lens in Example 1. In the aspheric coefficient of the lens data, 1 (x) and 4 (x) indicate that only the cross section in the X direction has an aspheric shape (the same applies to the following examples). 5A and 5B are cross-sectional views of the reduction relay optical system and the light-receiving lens of the first embodiment. FIG. 5A is a cross section in the X direction (a road surface parallel direction), and FIG. The reduction relay optical system and the light receiving lens according to the first exemplary embodiment include, in order from the object side, an aperture stop S, a first plastic lens L1, a second plastic lens L2, and a third glass lens L3. D is a light receiving surface of the light receiving element. As is apparent from FIG. 5, when a light beam is incident on a Galileo-type reduction relay optical system composed of the first lens L1 and the second lens L2 in the X-direction cross section, it is transmitted as it is in the Y-direction cross section and in the X-direction cross section. The spot image on the light receiving surface D formed by the reduction relay optical system and the light receiving lens is refracted and the width of the image in the X direction is enlarged as shown in FIG.

[table 1]
[Example 1]
SURF DATA Effective radius (mm)
NUM.rx ry d nd vd xy
OBJ INFINITY INFINITY 18e + 005
S INFINITY INFINITY 0.0000 12.5 7.0
1 * 24.6789 INFINITY 6.0000 1.54470 55.81 12.5 7.0
2 INFINITY INFINITY 17.1000 12.0 7.2
3 INFINITY INFINITY 3.0000 1.54470 55.81 7.7 7.2
4 * 12.4014 INFINITY 10.0000 6.9 7.3
5 * 15.4694 15.4694 8.5588 1.58912 61.25 6.9 7.3
6 INFINITY INFINITY 21.2200 5.8 6.1
D INFINITY INFINITY 0.0000

ASPHERICAL SURFACE
1 (x) K = 0.00000e + 000, A4 = -1.85097e-005, A6 = -9.21528e-009, A8 = 1.28857e-010
4 (x) K = 0.00000e + 000, A4 = -2.53534e-004, A6 = 1.62967e-006, A8 = -3.24888e-009
5 K = -1.04648e + 000, A4 = 1.63546e-005, A6 = 9.86765e-009, A8 = -8.43461e-013


Single lens data s line
Lens Start surface Focal length (mm)
xy
1 1 46.2 INFINITY
2 3 -23.2 INFINITY
3 5 26.6 26.6

(Example 2)
Table 2 shows lens data of the reduction relay optical system and the light receiving lens in Example 2. 6A and 6B are cross-sectional views of the reduction relay optical system and the light receiving lens according to the second embodiment. FIG. 6A is a cross section in the X direction (the road surface parallel direction), and FIG. The reduction relay optical system and the light receiving lens of Example 2 are composed of an aperture stop S, a glass first lens L1, a glass second lens L2, and a glass third lens L3 in this order from the object side. D is a light receiving surface of the light receiving element. As is clear from FIG. 6, when the light beam enters the Kepler type reduction relay optical system including the first lens L1 and the second lens L2 in the X direction cross section, the light beam is allowed to pass through in the Y direction cross section, and in the X direction cross section. The spot image on the light receiving surface D formed by the reduction relay optical system and the light receiving lens is refracted and the width of the image in the X direction is enlarged as shown in FIG. In the reduction relay optical system according to the second embodiment, since the light flux is converged between the first lens L1 and the second lens L2, a light shielding member SH provided with a slit is disposed here, thereby eliminating unnecessary light. It can be carried out.

[Table 2]
[Example 2]
SURF DATA Effective radius (mm)
NUM.rx ry d nd vd xy
OBJ INFINITY INFINITY 18e + 005
S INFINITY INFINITY 0.0000 12.5 7.0
1 * 12.5952 INFINITY 9.9807 1.67269 32.20 12.5 7.0
2 INFINITY INFINITY 15.5625 11.3 7.0
3 INFINITY INFINITY 2.4568 1.67269 32.20 2.2 7.1
4 * -2.5190 INFINITY 10.0000 2.6 7.2
5 * 14.4925 14.4925 4.0000 1.58912 61.25 2.8 7.3
6 INFINITY INFINITY 22.5095 2.7 6.9
D INFINITY INFINITY 0.0000

ASPHERICAL SURFACE
1 (x) K = -9.61976e-001, A4 = 2.54755e-005, A6 = 2.92867e-008, A8 = -6.14135e-011
4 (x) K = -7.91190e-001, A4 = -1.78252e-003, A6 = -9.64333e-005, A8 = 8.05859e-006
5 K = -1.13846e + 000, A4 = 2.04371e-005, A6 = 4.60626e-008, A8 = -2.43841e-010

Single lens data s line
Lens Start surface Focal length (mm)
xy
1 1 19.2 INFINITY
2 3 3.8 INFINITY
3 5 24.9 24.9

  Table 3 summarizes the numerical values of the conditional expressions in Examples 1 and 2.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. The description and examples are for illustrative purposes only, and the scope of the invention is indicated by the following claims. For example, the polygon mirror may be a hexagonal column or an octagonal column instead of a quadrangular column.

  In FIG. 3, the polygonal rotation axis and the optical axis of the light projecting / receiving optical system intersect with each other. However, the present invention is not limited to this, and the polygonal rotation axis is the vertical direction and the reflection surface is the rotation axis. In contrast, the optical axis of the light projecting / receiving optical system may be arranged in parallel to the rotation axis while being inclined at about 45 degrees with respect to each surface. In the above embodiment, the optical system using a cylindrical lens has been described. However, a reduction relay optical system including an anamorphic lens having different horizontal and vertical curvatures may be used.

DESCRIPTION OF SYMBOLS 1 Vehicle 1a Front window 1b Front grille BF Band pass filter CL Collimating lens D Light receiving surface G of light receiving element Screen L1 First lens L2 Second lens L3 Light receiving lens LD Semiconductor laser LR Laser radar O Rotating axis OBJ Object PD Light receiving element PM Polygon mirror PM1-PM4 Reflective surface ROS Reduction relay optical system

Claims (8)

Light projection comprising: a laser light source; a collimating lens that converts divergent light from the laser light source into parallel light; and a first reflecting member that scans and projects laser light that has been collimated by the collimating lens onto a target region. Optical system,
A second reflecting member that reflects the reflected light from the target area that has been scanned and projected, and a reduction that includes a plurality of lenses for shaping the reflected light from the target area that is reflected by the second reflecting member A light receiving optical system comprising: a relay optical system; and a light receiving lens that condenses the light shaped by the reduction relay optical system on a light receiving surface of a light receiving element;
The cross section of the light beam projected from the light projecting optical system has a larger spread angle in the vertical direction than in the horizontal direction, and the reduction relay optical system satisfies the following expression.
mv <mh (1)
mh> 1 (2)
However,
mv: angular magnification in the vertical direction of the reduction relay optical system mh: angular magnification in the horizontal direction of the reduction relay optical system The laser radar according to claim 1, wherein the following equation is satisfied.
0.17 <mv / mh <0.70 (3)   The laser radar according to claim 1 or 2, wherein the reduction relay optical system is a Kepler type at least in a horizontal section.   3. The laser radar according to claim 1, wherein the reduction relay optical system is a Galileo type at least in a horizontal section.   The laser radar according to any one of claims 1 to 4, wherein a band pass filter is disposed between the reduction relay optical system and the light receiving lens.   6. The laser radar according to claim 1, wherein the first reflecting member and the second reflecting member are common.   The first reflection member and the second reflection member are polygon mirrors that are rotatable about a rotation axis along a vertical direction and have a plurality of reflection surfaces on the side surfaces, and an angle of the reflection surface with respect to the rotation axis The laser radar according to any one of claims 1 to 6, wherein each is different from each other.   The laser radar according to any one of claims 1 to 7, wherein the laser radar is for in-vehicle use.

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