JPH0894757A - Laser radar - Google Patents

Abstract

PURPOSE: To satisfy the achievement of the scan linearity of transmitted light, the compact configuration of a device and the simplification of the mechanism at the same time. CONSTITUTION: Laser light is emitted from a laser light source 25 of a light transmitting optical system 21, reflected from the conical surface of a variable- angle cone mirror 28 and directed toward an object. The laser light (reflected light) reflected from the object is cast into a fly-eye 41 of a receiving optical system 23 and detected with a photodetector 43 through a Fresnel lens 42. The variable-angle cone mirror 28 has the conical surface, whose apex angle is gradually changed in the circumferential direction. Therefore, when the variable-angle cone mirror 28 is rotated in the constant direction at the constant speed at the time of transmission, the reflecting direction of the laser light at the conical surface is changed, and the scanning of the transmitted light directed toward the object is performed. Since the variable-angle cone mirror 28 is simply rotated in the constant direction at the constant speed, the scanning linearity of the transmitted light is realized. The speed control of the rotation of the variable-angle cone mirror 28 is not required, and the compact configuration of the device and the simplification of the mechanism can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a transmitting optical system for emitting a laser beam and a receiving optical system for receiving a reflected beam of a laser beam emitted from the transmitting optical system which is reflected by an object. The present invention relates to a laser radar that detects the position of the object based on.

[0002]

2. Description of the Related Art The laser radar described above is used, for example, in a vehicle (mainly an automobile) to detect the distance between the vehicle and the vehicle ahead. FIG. 16 shows an example of the configuration of a conventional laser radar of this type. In the figure, laser light emitted from a laser light source 1 passes through a collimator lens 2 and a cylindrical lens 3,
It becomes an elongated light beam, is reflected by the plane mirror 4 for transmission, and illuminates an object 5 such as a vehicle ahead. The reflected light reflected by the object 5 is reflected by the receiving plane mirror 6, condensed by the condenser lens 7, and detected by the light receiving element 8. Then, in order to detect an object in a certain range on the left and right in the horizontal direction ahead,
The plane mirrors 4, 6 are driven by the driving device 9 via the rotary shaft 10.
17 is rotated reciprocally as shown in FIG.
Laser light toward) is scanned within a certain angle range. The plane mirrors 4 and 6 in the illustrated example are integrated. And
Although a detailed description is omitted, in the control unit (not shown), the laser light is emitted from the laser light source 1 and then reflected and received by the light receiving element 5.
The time until the light is received is detected to detect the distance to the object 5, and the direction of the object 5 is detected based on the rotation angles of the plane mirrors 4 and 6 at that time.

[0003]

The conventional laser radar 11 described above has the following drawbacks. Regarding the transmission system, it is desirable that the angle change in the scan direction of the transmitted light be the angular change of the uniform angular velocity, that is, the scan linearity of the transmitted light can be realized. In order to realize the scan linearity of the transmitted light, the rotation speed of the plane mirror 4 that rotates reciprocally must be constantly changed, but since it is reciprocating rotation, the speed changes without fail when the direction is changed. , It is difficult to get perfect scan linearity. In order to obtain as high a scan linearity as possible, the drive unit 9 needs a special mechanism for controlling the rotation speed, which makes the drive unit mechanically complicated and large. In this way, the scan linearity and the miniaturization of the transmission system device or the simplification of the mechanism restrict each other, and in the conventional transmission system, the scan linearity and the miniaturization of the device and the simplification of the mechanism are required. Could not be satisfied at the same time.

Regarding the receiving system, the light receiving element 8 can receive reflected light from a wide angle range, that is, the light receiving angle is wide, and the light receiving element 8 can effectively receive reflected light from the object 3, that is, light reception. It is desired that the efficiency is high, the device is small, and the mechanism is simple. However, these cannot be sufficiently satisfied by the conventional structure. Regarding the light receiving angle, since the reflected light is simply condensed by the condenser lens 7, if the principal ray of the laser light incident on the condenser lens 7 has an angle with respect to the optical axis of the condenser lens 7. The light receiving position (light spot position) of the laser beam on the light receiving element 8 moves and easily deviates from the light receiving element 8.
Therefore, the allowable reception angle in the conventional receiving system is narrow.
On the other hand, since the reflected light from the object 5 covers a certain angle range in the scanning direction, it is unavoidable that the principal ray of the laser light incident on the condenser lens 7 has an inclination angle, and therefore deviates from the light receiving element 8. Laser light is likely to be generated and the light receiving efficiency becomes low. As described above, the conventional receiving system cannot satisfy both the wide light receiving angle and the high light receiving efficiency.

The present invention has been made to solve the above-mentioned conventional drawbacks, and can simultaneously satisfy both the scan linearity of transmission light in a transmission optical system, the downsizing of an apparatus, and the simplification of a mechanism. An object of the present invention is to provide a laser radar, and an object of the present invention is to provide a laser radar capable of simultaneously satisfying both a wide light receiving angle and a high light receiving efficiency in a receiving optical system.

[0006]

According to a first aspect of the present invention, which solves the above-mentioned problems, a transmitting optical system for emitting a laser beam and a reflected light reflected by an object of the laser beam emitted from the transmitting optical system are received. In a laser radar that includes a receiving optical system that detects the position of the object based on a received light signal,
The transmission optical system is a vari-angle cone mirror having a conical surface whose apex angle gradually changes in the circumferential direction as a reflecting surface, so that the conical axis is parallel to the optical axis of the laser light emitted from the laser light source. Further, a drive device is provided so that the conical surface is located on the optical axis and the vari-angle cone mirror is rotationally driven at a constant rotational speed.

According to a second aspect of the present invention, there is provided a transmission optical system for emitting laser light, and a reception optical system for receiving reflected light of the laser light emitted from the transmission optical system which is reflected by an object.
In the laser radar that detects the position of the object based on the received light signal, the receiving optical system includes a fly eye that is a bundle of a large number of elements, both surfaces of which are convex lenses at the paraxial focus position of the other surface. It is characterized in that it is provided with a condenser lens arranged so that the rear focal position is located at the exit surface position of the fly's eye, and a light receiving element arranged at the front focal position of the condenser lens.

According to a third aspect of the present invention, instead of the fly's eye of the second aspect, 2 having an equivalent refracting power arranged at intervals.
The fly-eye is composed of a single lens array plate, and a pair of opposing convex lens portions in each lens array plate share the optical axis of the lens, and fly eyes are provided at the focal positions of the convex lens portions on the other side.

The invention of claim 4 is characterized in that a Fresnel lens is used as a condenser lens in the laser radar of claim 2 or 3.

The invention of claim 5 is characterized in that the cross-sectional shape of each element of the fly's eye in the laser radar of claim 2 or 3 is a rhombus having a long diagonal in the scanning direction of the transmitted light.

According to a sixth aspect of the present invention, in the laser radar according to the first aspect, the vari-angle cone mirror is parallel to the optical axis of the laser light emitted from the laser light source of the transmission optical system and with respect to this optical axis. A laser light source for angle detection that has an optical axis shifted by a certain angle around the cone axis and emits laser light toward the conical surface of the vari-angle cone mirror, and a vari-angle cone mirror for the laser light from this laser light source. And an angle detection optical system that detects the laser beam irradiation position on this position sensor by the output of the position sensor and detects the rotation angle of the vari-angle cone mirror. It is characterized by having.

According to a seventh aspect of the present invention, the vari-angle cone mirror in the sixth aspect includes a conical surface portion on which the laser light from the transmission optical system strikes and a conical surface portion on which the laser light from the angle detection optical system is reflected. Is characterized by being concentrically divided.

According to the present invention, there is provided a transmission optical system for emitting laser light, and a reception optical system for receiving the reflected light of the laser light emitted from the transmission optical system which is reflected by an object.
In a laser radar that detects the position of the object based on a received light signal, the transmission optical system according to claim 1 is used as the transmission optical system, and the reception optical system according to claim 2 or 3 is used as the reception optical system. A laser beam emitted from a laser light source of the transmission optical system is formed between a fly-eye and a condenser lens of the reception optical system such that the optical axes of the reception optical system and the transmission optical system are orthogonal to each other. It is characterized in that it is arranged so as to pass through the gap or the gap between the condenser lens and the light receiving element.

According to a ninth aspect of the present invention, there is provided a transmission optical system for emitting laser light, and a reception optical system for receiving the reflected light of the laser light emitted from the transmission optical system which is reflected by an object.
In a laser radar that detects the position of the object based on a received light signal, the transmission optical system according to claim 1 is used as the transmission optical system, and the reception optical system according to claim 2 or 3 is used as the reception optical system. The angle detection optical system according to claim 3 is used as an angle detection optical system for detecting the rotation angle of the variangle cone mirror of the transmission optical system,
A laser beam emitted from the laser light source of the transmission optical system is arranged so that the optical axes of the reception optical system and the transmission optical system are orthogonal to each other, and the gap between the fly's eye of the reception optical system and the condenser lens. And the laser light source emitted from the laser light source of the angle detection optical system is arranged so as to pass through the gap between the condenser lens and the light receiving element.

[0015]

The variable angle cone mirror is rotated in the same direction at a constant speed. When laser light is emitted from the laser light source of the transmission optical system toward the conical surface of the variangle cone mirror, the laser light is reflected by the conical surface of the variangle cone mirror and travels toward the object. In this case, since the apex angle of the conical surface of the variangle cone mirror gradually changes in the circumferential direction, the reflection direction of the laser light on the conical surface changes as the variangle cone mirror rotates. That is, the transmission light is scanned. As described above, since the transmitted light is continuously scanned by the vari-angle cone mirror that rotates at a constant speed, the angle change in the scan direction of the transmitted light is a constant speed angle change. That is,
Scan linearity of transmitted light is secured.

In claim 2, the laser light emitted from the transmission optical system is directed to the object, and the reflected light reflected by the object is incident on each element of the fly's eye of the reception optical system.
Since both sides of each element are located at the paraxial focus position of the other side, the chief ray of the laser light incident on each element has an emission angle of zero regardless of the incident angle of the laser light. On the other hand, since the back focal position of the condenser lens is at the exit surface position of the fly's eye, all the laser light incident on each element of the fly's eye must pass through the exit pupil at the front focal position of the condenser lens. become. Since the light receiving element is arranged at this front focus position, all the laser beams incident on the fly's eye reach the light receiving element regardless of the incident angle. As described above, this receiving optical system can receive the laser light incident on the fly's eye from a wide angle range, and can also receive all the laser light incident on the fly's eye by the light receiving element (however, When ignoring the aberration of the condenser lens). That is, a wide light receiving angle and a high light receiving efficiency can be satisfied at the same time.

A fly eye according to claim 3 is the fly eye according to claim 2.
Has the same effect as the fly eye in. In this case, the fly eye element in the fly eye according to claim 2 corresponds to the pair of convex lens portions facing each other in the two lens array plates according to claim 3.

In the present invention, since the Fresnel lens is used as the condenser lens of the receiving optical system, the receiving optical system can be made thin.

In the fifth aspect, since each element of the fly's eye has a rhombic cross section having a long diagonal line in the scanning direction, it is possible to realize a wide allowable light receiving angle in the scanning direction. Even if the allowable light receiving angle in the direction perpendicular to the scanning direction is narrow, the performance as a laser radar is not impaired,
No problem.

In the sixth aspect, the laser light emitted from the laser light source of the angle detection optical system is reflected by the conical surface of the vari-angle cone mirror and irradiates the position sensor (forms a light spot). Since the laser light irradiation position (light spot position) on the position sensor is determined by the apex angle of the conical surface, if the light receiving position is detected based on the output of the position sensor, the apex angle of the conical surface can be detected. Thus, the rotation angle position of the vari-angle cone mirror can be detected. By this angle detection, the direction (angle) of the transmitted light toward the object can be detected, and the direction of the object can be detected.

In the present invention, since the vari-angle cone mirror is concentrically divided into the conical surface portion for the transmission optical system and the conical surface portion for the angle detection optical system, an appropriate apex angle is provided for each. Can be selected.

In the eighth aspect, the laser light emitted from the laser light source of the transmission optical system passes through the gap between the fly eye and the condenser lens of the reception optical system or the gap between the condenser lens and the light receiving element, and the vari angle. It is incident on a cone mirror, reflected by a vari-angle cone mirror, toward an object, and reflected by the object. The reflected light reflected by the object enters the fly's eye of the light receiving element, is condensed by the condenser lens, and is detected by the light receiving element. Since the space of the receiving optical system is effectively used as the passage of the laser light in the transmitting optical system, the size of the laser radar device can be reduced.

In claim 9, the laser light emitted from the laser light source of the transmission optical system enters the vari-angle cone mirror through the gap between the fly's eye of the reception optical system and the condenser lens, and the vari-angle cone mirror. It is reflected by and goes to the object, and is reflected by the object. The reflected light reflected by the object is
The light enters the fly's eye of the light receiving element, is condensed by the condenser lens, and is detected by the light receiving element. On the other hand, the laser light emitted from the laser light source of the angle detection optical system passes through the gap between the condenser lens and the light receiving element of the reception optical system, enters the vari-angle cone mirror, and is reflected by the vari-angle cone mirror. It is detected by the light receiving element for angle detection. As the passage of each laser light in the transmission optical system and the angle detection optical system,
In both cases, the space of the receiving optical system is effectively used,
The size of the laser radar device can be reduced.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan view showing the internal structure of a laser radar according to the present invention, and FIG. 2 is a front view thereof. The laser radar 20 of this embodiment is mounted on a vehicle to detect the position (direction and distance) of the vehicle ahead, and a transmission optical system 21 for emitting laser light to the inside, and this transmission optical system 2
1. An angle detection optical system 22 for detecting the direction of laser light (transmitted light) emitted from 1 toward an object, the object (vehicle)
Receiving optical system 2 for receiving laser light (reflected light) reflected by
3 is provided in the case 24. In each figure, the scanning direction (horizontal direction) of the transmitted light is indicated by x, the direction of the transmitted light toward the object is indicated by y, and the vertical direction is indicated by z.

As shown in FIGS. 3 and 4, the transmission optical system 21 includes a laser light source 25 for emitting high-frequency pulsed laser light, a collimator lens 26 for collimating the emitted laser light, and a parallel light source. Cylindrical lens 27 that collects light only in one vertical and horizontal direction (z direction in the figure), vari-angle cone mirror 2 that reflects laser light toward an object
8. A motor 30 is provided for rotating the rotary shaft 29 of the vari-angle cone mirror 28 at a constant rotational speed.
The rotation axis 29 coincides with the cone axis of the variangle cone mirror 28. Bali angle cone mirror 28
6 to 8, the apex angle α of the conical surface 28a is
(In the present specification, the conical surface 28a has a conical shaft 28b.
The angle with respect to is referred to as the apex angle) is gradually changed in the circumferential direction, and a step portion 28c in which the apex angle α of the conical surface 28a changes discontinuously is formed at a position where it makes one revolution. The vari-angle cone mirror 28 is preferably made of, for example, aluminum or plastic, and the surface thereof may be vapor-deposited with aluminum or the like to form a reflecting surface. The vari-angle cone mirror 28 has a cone axis 28b.
Is parallel to the optical axis K ₁ of the laser light emitted from the laser light source 25, and its conical surface 28a has an optical axis K ₁
It is placed so that it is on top.

As shown in FIGS. 3 and 9, the angle detecting optical system 22 is an optical component common to both the transmitting optical system 21 and the angle detecting optical system 22, and the above-mentioned variangle cone. A mirror 28, a laser light source 35 that emits laser light, and a converging lens 36 that converges the emitted laser light onto the vari-angle cone mirror 28.
And a position sensor 37 which is a light receiving element for receiving the laser beam reflected by the variangle cone mirror 28 and detecting the light receiving position (light spot position). The position sensor 37 outputs a signal according to the actual light receiving position in the light receiving area. The relationship between the optical axis K ₂ of the optical axis K ₁ and the angle detection optical system 22 of the transmission optical system 21, as shown in FIG. 9, the angle parallel, and the rotary shaft 29 around the vari-angle cone mirror 28 to each other The relationship is shifted by θ (180 ° in the illustrated example).

The receiving optical system 23 is shown in FIGS.
As shown in FIGS. 13 (a) and 13 (b), a fly eye 41 is formed by bundling a large number of elements 40, which are convex lenses, both surfaces of which are at the paraxial focus position of the other surface, and the emission of this fly eye 41. A Fresnel lens 42 as a condenser lens is arranged so that the rear focal position F ₁ is located at the surface position, and a light receiving element 43 is arranged at the front focal position F ₂ of the Fresnel lens 42. In this embodiment, each element 40 of the fly's eye 41 has a rhombic cross-sectional shape as shown in the drawing, and a large number of these rhombic elements 40 are joined together without a gap.

The operation of detecting the position of an object by the laser radar will be described. Bali Angle Cone Mirror 2
The motor 8 is driven by a motor 30 via a rotary shaft 29 and rotates at a constant speed. Laser light source 2 of transmission optical system 21
5, pulsed laser light is emitted toward the conical surface 28a of the variangle cone mirror 28. The emitted laser light is emitted from the conical surface 28a of the variangle cone mirror 28.
Reflects at and goes toward the object. In this case, since the apex angle α of the conical surface 28a of the vari-angle cone mirror 28 gradually changes in the circumferential direction, the rotation direction of the vari-angle cone mirror 28 changes the reflection direction of the laser light on the conical surface 28a. . That is, in FIG. 3, the transmitted light is swayed to the left and right, and scanning is performed with a thin line-shaped light beam (schematically indicated by a line 31). In this case, Bali Angle Cone Mirror 2
When 8 is rotated once, one scan of the transmitted light is performed. Also, the scanning direction is not reciprocating but only one direction. In the above description, since the vari-angle cone mirror 28 does not reciprocally rotate but rotates in the same direction, the rotation speed is always constant and the scan linearity of transmitted light is ensured.

The reflection direction and the luminous flux shape on the conical surface 28a of the vari-angle cone mirror 28 described above will be described in detail. Now, assuming that a parallel light beam is incident on the vari-angle cone mirror 28,
Has no power in the gradient direction of the conical surface 28a (indicated by the arrow (a) in FIG. 6; this direction has a slight angle with respect to the plane including the conical axis 28a), so the reflected light also The diameter of the incident parallel light flux is maintained. However, with respect to the non-gradient directions, the light is reflected while diverging according to the power of the surface in each direction.
Therefore, the reflected light as a whole becomes an elliptic divergent light flux with a very large eccentricity. The eccentricity of the divergent light beam is controlled by appropriately selecting the focal length of the cylindrical lens 27 arranged in the laser light incident on the variangle cone mirror 28 (that is, the divergence ratio of the divergent light beam (the size of the elliptical shape)). And the oblateness of the elliptical shape can be controlled). This is shown in FIG. In the embodiment, the width h is converged to the width s in the z direction (vertical direction) in FIG. 4, and the converged width s diverges after reflection (diverges in the direction indicated by the width S). On the other hand, the light beam width h in the direction perpendicular to the width s (light beam width in the y direction) h is constant after reflection. An elliptical divergent light flux having this width h and a diverging width S is directed to the object as transmission light.

The laser light (transmitted light) reflected by the vari-angle cone mirror 28 becomes an elliptical light flux toward the object as described above, irradiates the surface of the object in a thin line shape, and is reflected by the object surface. The (reflected light) enters each element 40 of the fly's eye 41 of the receiving optical system 23. Both surfaces of each element 40 are located at the paraxial focus position of the other surface, so that the principal ray m of the laser light incident on each element 40 is the laser light, as shown in FIG. The output angle is zero regardless of the incident angle β of (i.e., parallel to the optical axis of the element 40). On the other hand, in the Fresnel lens 42, the focus position F ₁ on the rear side is the fly eye 41.
Since the laser light transmitted through the Fresnel lens 42 becomes a parallel light flux as shown in an enlarged view of the main part in FIG. The exit pupil at the position F ₂ (the shape of the exit pupil viewed from the front of the light receiving element 43 is denoted by reference numeral 44).
(Indicated by) will be passed. This front focus position F ₂
Since the light receiving element 43 is arranged in the
All the laser light that has entered the photodetector reaches the light receiving element 43 regardless of the incident angle β. In this case, the light receiving element 43
May use the diameter of the exit pupil as the effective light receiving diameter, and does not needlessly require a large light receiving area. As described above, the receiving optical system 23 can receive the laser light that has entered the fly's eye 41 from a wide angle range, and can receive all the laser light that has entered the fly's eye 41.
Can receive light (however, when aberration of the condenser lens is ignored, as will be described later). That is, it is possible to simultaneously satisfy a wide light receiving angle and a high light receiving efficiency (the ratio of the light received by the light receiving element 43 to the light incident on the fly's eye 41).

Design problems in determining the optical parameters of the fly-eye 41, the Fresnel lens 42, and the light-receiving element 43 of the receiving optical system 23, especially the Fresnel lens 42.
A brief description will be given of the problem in determining the focal length of the. In the above description, the aberration of the Fresnel lens 42 is neglected, but in reality, due to the aberration of the Fresnel lens 42, a light beam that deviates to the side of the light receiving element 43 also occurs. The degree becomes more remarkable as the focal length of the Fresnel lens 42 becomes shorter, when the effective diameter of the fly eye 41 is constant. Therefore, in order to increase the light receiving efficiency, the longer the focal length of the Fresnel lens 42 is, the better as to the problem of aberration. On the other hand, if the incident NA to the Fresnel lens 42 is constant, the longer the focal length of the Fresnel lens 42, the larger the pupil diameter. However, generating a pupil that is larger than the effective area of the light receiving element 43 leads to a decrease in light receiving efficiency. Therefore, there is an upper limit to the focal length of the Fresnel lens 42. On the other hand, in order for all the light fluxes incident on the fly-eye 41 to be effectively emitted from the fly-eye 41, the inclination angle of the incident light flux and the NA of the emitted light flux must match. N of the luminous flux emitted from this fly eye 41
Since A is the incident NA to the Fresnel lens 42, the maximum value of the principal ray inclination angle of the light beam incident on the fly's eye 41 eventually governs the NA of the Fresnel lens 42, and is combined with the effective light receiving diameter of the light receiving element 43. The upper limit of the focal length of the Fresnel lens 42 is defined. Depending on the optical parameters thus obtained, a large aberration is usually generated. In particular, with respect to the Fresnel lens 42, the focal length is too short, and large aberration occurs. Therefore, it becomes difficult to correct the generated aberration, and the final optical system parameter is finally determined by selecting the optimum solution that mediates the aberration.

By the way, in the laser radar 20 described above, since the scanning direction is only one direction in the horizontal direction, the receiving optical system 21 is required to be able to receive the reflected light beam from a wide angle range in the horizontal direction, while in the vertical direction. May be narrow. That is, the maximum principal ray tilt angle of the incident light flux to the fly eye 41 that is allowable for being received by the light receiving element 43 differs between the vertical direction and the horizontal direction (that is, the maximum allowable principal ray tilt angle of the incident light flux is anisotropic. There is a nature). That is,
As a receiving optical system of the laser radar, it is suitable that the light receiving angle is wide in the horizontal direction and narrow in the vertical direction. However, since each element 41 of the fly-eye 41 in the present invention has a rhombic cross section having a long diagonal line in the scanning direction, it is compared with the case where the cross section of the element is a non-anisotropic shape such as a square or a regular hexagon. Then, the light receiving angle in the vertical direction is narrow, but the light receiving angle in the horizontal direction is wide. Even if the allowable light receiving angle in the vertical direction is narrow, the performance of the laser radar 20 that scans in the horizontal direction is not impaired. Therefore, the receiving optical system 23 has a wide light receiving angle as the receiving optical system of the laser radar. The cross-sectional shape of the element 40 in the illustrated example has an allowable light-receiving angle of ± 1 in the horizontal direction, for example.
It is set to 0 ° and ± 3 ° in the vertical direction. The aspect ratio of the rhombus cross section of the element 40 may be appropriately set in consideration of both the scan angle range and the required light receiving angle with respect to the vertical direction.

Next, the operation of detecting the rotation angle of the vari-angle cone mirror 28 will be described. The laser light emitted from the laser light source 35 of the angle detection optical system 22 is converged by the converging lens 36 on the conical surface 28 a of the vari-angle cone mirror 28 and reflected. In this embodiment, the reflected light is reflected at a position 180 ° opposite to the reflected position of the transmitted light on the conical surface 28a of the vari-angle cone mirror 28, and reflected in the direction opposite to the reflected direction of the transmitted light. Then, a light spot is formed on the position sensor 37 after reflection. If the position of the light spot is detected based on the output of the position sensor 37, it is possible to detect the apex angle of the conical surface 28a hit by the laser light for angle detection, and thus the rotation angle of the vari-angle cone mirror 28. The position can be detected.
By this angle detection, the direction of the transmitted light toward the object can be detected, and the direction of the object can be detected.

In the laser radar 20 described above, the optical axis of the receiving optical system 23 is orthogonal to the optical axis of the transmitting optical system 21, and the fly's eye 41 and the Fresnel lens are used as the passage of the laser light in the transmitting optical system 21. The space between the Fresnel lens 42 and the light receiving element 43 is used as a passage for the laser light source 35 in the angle detection optical system 22.
The space between the receiving optical system 23 and
Since the space is effectively used, the device of the laser radar 20 is downsized.

FIGS. 13 (c) and 13 (d) show a fly eye 41 'having substantially the same function as the fly eye 41 in which the elongated elements 40 are bundled but having a different structure. As shown in FIG. 13C, the fly's eye 41 ′ is composed of two lens array plates 41′a and 41′b having an equivalent refracting power and arranged at intervals, )
As shown in, the pair of opposing convex lens portions 40 'in each lens array plate 41'a, 41'b share the lens optical axis, and are at the focal positions of the mutually opposing convex lens portions 40'. The shape of each convex lens portion 40 'in the lens array plates 41'a and 41'b is a rhombus like the element 40 of the fly-eye 41 described above, and the pair of convex lens portions 40' facing each other are optically It works the same as the individual elements 40 of the fly eye 41 described above. The fly-eye 41 'made of this lens array plate is inferior in optical accuracy to the fly-eye 41 in which elements are bundled, because it is difficult to match the optical axes of the incident side and the exit side with sufficiently high accuracy, but This lens array plate structure can be adopted because almost no strict accuracy is required for radar applications. Further, the fly eye having this structure can be manufactured at a lower cost than the structure in which the elements are bundled.

Another embodiment of the variangle cone mirror is shown in FIGS. In the vari-angle cone mirror 51 of this embodiment, a conical portion 52 that reflects the laser light from the transmission optical system 21 and a conical portion 53 that reflects the laser light from the angle detection optical system 22 are concentrically divided. There is. In the conical portion 52 for the transmission optical system 21, the apex angle of the conical surface 52a gradually changes in the circumferential direction, like the vari-angle cone mirror 28 shown in FIGS. Step 52c due to discontinuity of apex angle at one location in the direction
Is a shape that is formed. The conical portion 53 for the angle detection optical system 22 is formed around the conical portion 52, and the apex angle of the conical surface 53a is also gradually changed in the circumferential direction, and the conical surface 53 is formed.
It is a shape in which a step portion 53c is formed at one location in the circumferential direction of a due to the discontinuity of the apex angle. Also in this case, the optical axis of the transmission optical system 21 and the optical axis of the angle detection optical system 22 form an angle θ around the conical axis 51b of the vari-angle cone mirror 51.
(180 ° in the figure).

In the present invention, the means for detecting the direction of the transmitted light toward the object is not limited to the angle detection optical system 22 of the embodiment, and for example, the rotation angle of the vari-angle cone mirror 28 may be the rotary encoder. It is possible to adopt a method of directly detecting such as by the above, or other method.

In the embodiment, the Fresnel lens 42 is used as the condenser lens of the receiving optical system 23, but an ordinary condenser lens which is a simple convex lens may be used. Further, the laser light source 25 in the transmission optical system 21 of the embodiment
Transmits pulsed laser light, but this is not always necessary. Continuous light may be used. Further, the transmission optical system 21 of the embodiment is provided with the cylindrical lens 27 to form a thin line-shaped transmission light beam. However, if a wide detection range is not required in the vertical direction, it may be just a perfect circular light transmission light beam. Further, the laser radar of the present invention is not limited to being mounted on an automobile, but can be used for various other purposes when it is mounted on other vehicles or when detecting materials or products in a manufacturing plant.

[0039]

According to the invention of claim 1, since the vari-angle cone mirror is used as the reflecting mirror for scanning the transmitted light, the vari-angle cone mirror is rotated in a constant direction at a constant speed. , The transmitted light can be continuously scanned, and therefore the scan linearity of the transmitted light is ensured. Further, the drive device for driving the vari-angle cone mirror does not require a special mechanism for speed control unlike the conventional one that reciprocally rotates the plane mirror, and the motor may simply rotate at a constant speed. Is small and simplifies the mechanism.

According to the second or third aspect of the present invention, since the receiving optical system is composed of the fly eye, the condenser lens and the light receiving element, the reflected light can be received from a wide angle range and the light is incident on the fly eye. All of the laser light generated can be received by the light receiving element. That is, it is possible to simultaneously satisfy a wide light receiving angle and a high light receiving efficiency.

According to the invention of claim 4, since the Fresnel lens is used as the condenser lens of the receiving optical system, the receiving optical system can be made thin.

According to the invention of claim 5, since each element of the fly eye has a rhombic cross section having a long diagonal line in the scanning direction, it is possible to realize a wide allowable light receiving angle in the scanning direction, and as a laser radar. The performance can be improved.

According to the sixth aspect of the present invention, since the laser light is applied to the variangle cone mirror and the rotation angle of the variangle cone mirror is detected by the reflected light, the angle of the transmitted light toward the object, that is, the object is detected. The direction of can be reliably detected.

According to the invention of claim 7, the vari-angle cone mirror is concentrically divided into a conical surface portion for the transmission optical system and a conical surface portion for the angle detection optical system.
A proper apex angle can be selected for each.

According to the invention of claim 8, the optical axis of the transmitting optical system and the optical axis of the receiving optical system are orthogonal to each other, and the space of the receiving optical system is effective as the passage of the laser light in the transmitting optical system. Since it is used, the size of the laser radar device can be reduced.

In the ninth aspect, the optical axis of the transmitting optical system and the optical axis of the angle detecting optical system and the optical axis of the receiving optical system are orthogonal to each other, and the passage of each laser beam in the transmitting optical system and the angle detecting optical system. As a result, since the space of the receiving optical system is effectively used, the size of the laser radar device can be further reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing an internal structure of a laser radar according to an embodiment of the present invention.

FIG. 2 is a front view showing an internal structure of the laser radar.

FIG. 3 is an enlarged view showing only a transmission optical system and an angle detection optical system in FIG.

FIG. 4 is a view on arrow A in FIG.

FIG. 5 is an enlarged view taken along arrow B in FIG.

6 is a magnified view of the variangle cone mirror in FIG. 4, showing only the variangle cone mirror in the laser radar.

FIG. 7 is a left side view of FIG.

FIG. 8 is a perspective view of the vari-angle cone mirror.

FIG. 9 is a perspective view illustrating a positional relationship between a transmission optical system and an angle detection optical system in the laser radar.

10 is an enlarged view of a receiving optical system in the laser radar of FIG.

11 is a left side view of FIG.

12 is an enlarged view of a main part in FIG.

FIG. 13 (a) is a fly eye 1 in FIG.
Fig. 2 (b) is an enlarged view of two elements, Fig. (B) is a left side view of Fig. (A), Fig. (C) is a side view showing an example of a fly eye having a structure different from the above fly eye, and Fig. (D). ) Is an enlarged view of a main part in FIG.

FIG. 14 is a front view showing another embodiment of the vari-angle cone mirror.

FIG. 15 is a left side view of FIG.

FIG. 16 is a perspective view showing a configuration of a conventional laser radar.

17 is a diagram for explaining scan linearity of transmitted light in the laser radar of FIG.

[Explanation of symbols]

 20 Laser Radar 21 Transmission Optical System 22 Angle Detection Optical System 23 Reception Optical System 25 Laser Optical Source of Transmission Optical System 26 Collimator Lens of Transmission Optical System 27 Cylindrical Lens 28, 51 Variangle Cone Mirror 52 Conical Part for Transmission Light 53 Angle Detection Conical portion 28a, 52a, 53a Conical surface 28b, 51b Conical axis 28c 52c, 53c Step portion 35 Laser light source of angle detection optical system 36 Converging lens of angle detection optical system 37 Position sensor 40 Fly's eye element 40 'Convex lens portion 41 , 41 'Fly's eye 41'a, 41'b Lens array plate 42 Fresnel lens (condensing lens) 43 Light receiving element

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Geiei Takeyama 8-6-27 Akasaka, Minato-ku, Tokyo Skyplaza Akasaka 201 Fujii Optical Co., Ltd.

Claims (9)

[Claims] 1. A transmission optical system for emitting laser light, and a reception optical system for receiving reflected light of the laser light emitted from the transmission optical system, which is reflected by an object. In the laser radar for detecting the position, the transmission optical system is a vari-angle cone mirror having a conical surface whose apex angle gradually changes in the circumferential direction as a reflecting surface, and the conical axis of the laser light emitted from the laser light source. It is characterized in that it is arranged so as to be parallel to the optical axis and its conical surface is on the optical axis, and that a drive device for rotationally driving this vari-angle cone mirror at a constant rotational speed is provided. Laser radar. 2. A transmission optical system for emitting laser light, and a reception optical system for receiving the reflected light of the laser light emitted from the transmission optical system, which is reflected by an object, and the optical system of the object based on the light reception signal. In the laser radar for detecting the position, the receiving optical system includes a fly eye that is a bundle of a large number of elements that are convex lenses, both surfaces of which are at the paraxial focus position of the other surface, and a rear surface at the exit surface position of this fly eye. A laser radar, comprising: a condenser lens arranged so that a side focal position comes, and a light receiving element arranged at a front focal position of the condenser lens. 3. A transmission optical system for emitting laser light, and a reception optical system for receiving the reflected light of the laser light emitted from the transmission optical system, which is reflected by an object, and the receiving optical system of the object based on the light reception signal. In a laser radar for detecting a position, the receiving optical system is composed of two lens array plates having an equivalent refractive power and arranged at intervals, and a pair of opposing convex lens portions in each lens array plate has a lens optical axis. And a converging lens arranged so that the rear focal position is located at the exit surface position of this fly eye, and the front focal position of this condensing lens. A laser radar characterized by comprising a light receiving element arranged at. 4. The laser radar according to claim 2, wherein a Fresnel lens is used as the condenser lens. 5. The laser radar according to claim 2, wherein the cross-sectional shape of each element of the fly-eye is a rhombus having a long diagonal line in the scanning direction of transmitted light. 6. An optical axis that is parallel to the optical axis of the laser light emitted from the laser light source of the transmission optical system and that is offset from this optical axis by a constant angle around the conical axis of the variangle cone mirror. A laser light source for angle detection that emits laser light toward the conical surface of the variangle cone mirror, and a position sensor arranged in the direction of reflection of the laser light from this laser light source on the surface of the variangle cone mirror. 2. An angle detection optical system for detecting the rotation angle of the vari-angle cone mirror by detecting the laser light irradiation position on the position sensor by the output of the position sensor. Laser radar. 7. The vari-angle cone mirror is concentrically divided into a conical surface portion on which the laser light from the transmission optical system strikes and a conical surface portion on which the laser light from the angle detection optical system is reflected. 7. The laser radar according to claim 6, wherein: 8. A transmission optical system for emitting a laser beam, and a reception optical system for receiving reflected light of a laser beam emitted from the transmission optical system, which is reflected by an object. In a laser radar for detecting a position, the transmitting optical system according to claim 1 is used as the transmitting optical system, the receiving optical system according to claim 2 or 3 is used as the receiving optical system, and the receiving optical system and the transmitting optical system are used. A laser beam emitted from the laser light source of the transmission optical system so that their optical axes are orthogonal to each other, and a gap between the fly eye and the condenser lens of the reception optical system, or a condenser lens. A laser radar characterized by being arranged so as to pass through a gap between the light receiving element. 9. A transmission optical system for emitting laser light, and a reception optical system for receiving reflected light of the laser light emitted from the transmission optical system, which is reflected by an object. In a laser radar for detecting a position, the transmission optical system according to claim 1 is used as the transmission optical system, the reception optical system according to claim 2 or 3 is used as the reception optical system, and a vari-angle cone of the transmission optical system is used. The angle detection optical system according to claim 5 is used as an angle detection optical system for detecting a rotation angle of a mirror, and the reception optical system and the transmission optical system are arranged so that their optical axes are orthogonal to each other, and the transmission optical system. The laser light emitted from the laser light source of the system passes through the gap between the fly-eye of the receiving optical system and the condenser lens, and the laser light source emitted from the laser light source of the angle detection optical system is Laser radar, characterized in that the serial condensing lens and arranged to pass through the gap between the light receiving element.