JPH07239405A - Reflection mirror - Google Patents

Abstract

PURPOSE:To obtain a novel reflection mirror which affords a change in reflection direction not possible heretofore. CONSTITUTION:This reflection mirror 28 has a circular conical surface 28a of the vertex changing gradually in a circumferential direction as its reflection surface. The mirror has a step part 28c at the circular conical surface 28a as the vertex changes gradually. The reflection mirror 28 is rotated at a specified speed around the axis of the circular cone in the case of using the reflection mirror 28 as a reflection mirror of, for example, a transmission optical system of a laser radar. The reflection direction of light is oscillated and scan of transmission light is executed by a change in the vertex according to rotation when a laser beam having the optical axis parallel with the axis of the circular cone is cast to the circular conical surface 28a. In such a case, the reflection mirror rotates in a specified direction at a specified speed and, therefore, the change in the reflection direction is linear. Namely, the scan linearity of the transmission light is assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel reflecting mirror which gives a reflection direction change which has never been seen.

[0002]

2. Description of the Related Art Conventionally, there are various types of reflecting mirrors. As general ones, there are plane mirrors, convex mirrors, concave mirrors, and further, there are a cone mirror having a simple conical surface as a reflecting surface, a polygon mirror having an outer peripheral surface of a polygonal column such as a hexagonal column as a reflecting surface, and the like. Each of the above reflecting mirrors gives a unique reflection direction to the incident light. Further, the change in the reflection direction when each reflecting mirror is rotated is also unique.

[0003]

Each of the above-mentioned reflecting mirrors is used depending on the application. For example, a plane mirror is usually used for a transmission optical system in a laser radar. In this case, the plane mirror is reciprocally rotated within a certain angle range to scan the laser light emitted from the laser light source toward the object, for example, horizontally in the left and right directions. However, in the method of scanning the transmitted light using the plane mirror, if the rotation speed of the plane mirror is not controlled, the angle change of the scan direction of the transmitted light is the angular change of the uniform angular velocity, that is, the scan of the transmitted light.・ Linearity cannot be realized. In such a case, it is desirable to have a reflecting mirror that can easily realize scan linearity of transmitted light. Further, the present invention is not limited to the above-described scanning of the transmitted light, and may be used for a new application as long as there is no change in the reflection direction when the reflecting mirror is rotated.

The present invention has been made in view of the above background, and it is an object of the present invention to provide a novel reflecting mirror which gives a change in the reflection direction which has not existed in the prior art when rotated.

[0005]

The reflecting mirror of the present invention for solving the above-mentioned problems is characterized in that a conical surface whose apex angle gradually changes in the circumferential direction is used as the reflecting surface.

[0006]

The above reflecting mirror is rotated in the same direction at a constant speed, for example. When light parallel to the cone axis is made incident on the conical surface of this reflecting mirror, the apex angle of the conical surface gradually changes in the circumferential direction.
The direction of reflection on the conical surface changes. In this case, the reflector is
Since it does not reciprocally rotate but simply rotates in a constant direction at a constant speed, the change in the reflection direction in this case is an angular change in the uniform angular velocity. Then, this change in the reflection direction is repeated for each rotation of the reflecting mirror. Therefore, when used as a reflecting mirror for scanning transmitted light in a laser radar, scan linearity of transmitted light can be easily realized.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is used as a reflecting mirror in a transmission optical system of a laser radar will be described below with reference to FIGS. FIG. 1 is a plan view showing the internal structure of the laser radar, and FIG. 2 is a front view thereof. The laser radar 20 is mounted on a vehicle to detect the position (direction and distance) of the vehicle in front of the laser radar 20. The transmission optical system 21 emits laser light to the inside, and the transmission optical system 21 directs the object toward an object. An angle detection optical system 22 for detecting the direction of the emitted laser light (transmission light) and a reception optical system 23 for receiving the laser light (reflected light) reflected by an object (vehicle) are provided in a 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 a high-frequency pulsed laser beam, a collimator lens 26 for collimating the emitted laser beam, and a parallel beam. A cylindrical lens 27 that focuses light in only one vertical and horizontal directions (z direction in the figure), a vari-angle cone mirror 28 that is a reflecting mirror of one embodiment of the present invention that reflects laser light toward an object, and this vari-angle. The cone mirror 28 is provided with a motor 30 for rotationally driving the rotation shaft 29 at a constant rotation speed. The rotation axis 29 coincides with the cone axis of the variangle cone mirror 28. The variable angle cone mirror 28, which is a reflecting mirror according to an embodiment of the present invention, has a conical surface 28, as shown in FIGS.
The apex angle α of a (in this specification, the angle of the conical surface 28a with respect to the conical axis 28b is referred to as the apex angle) gradually changes in the circumferential direction, and the apex angle of the conical surface 28a at a position where it makes one revolution. It has a shape in which a step portion 28c in which α changes discontinuously is formed. 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 its conical axis 28b parallel to the optical axis K ₁ of the laser light emitted from the laser light source 25, and its conical surface 28a lies on the optical axis K _1. Are arranged as follows.

As shown in FIG. 3, the angle detecting optical system 22 includes the transmitting optical system 21 and the angle detecting optical system 2.
2 and the above-mentioned vari-angle cone mirror 28, which is an optical component common to both, and a laser light source 3 for emitting laser light.
5, a converging lens 36 that converges the emitted laser light toward the variangle cone mirror 28, and the laser light reflected by the variangle cone mirror 28 is received to detect the light receiving position (light spot position). The position sensor 37 is a light receiving element. The position sensor 37 outputs a signal according to the actual light receiving position in the light receiving area.

The receiving optical system 23 has a fly-eye 41 in which a large number of elements 40, which are convex lenses, both surfaces of which are at the paraxial focal point of the other surface, are bundled, and a rear side of the fly-eye 41 at the exit surface position. A Fresnel lens 42 as a condenser lens arranged so that the focal position comes and a light receiving element 43 arranged at the front focal position of the Fresnel lens 42.
It has and.

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 linear light beam (schematically indicated by a line segment 31). In this case, one rotation of the variangle cone mirror 28 causes one scan of the transmitted light. 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 luminous flux toward the object as described above, irradiates the surface of the object in a fine line shape, reflects on the object surface, and then Fresnel. The light is collected by the lens 42 and received by the light receiving element 43. The distance to the object is detected based on the signal from the light receiving element 43. Further, the direction of the object is detected based on the signal from the position sensor 37 of the angle detection optical system 22.

Another embodiment of the reflecting mirror of the present invention, that is, a variangle cone mirror is shown in FIGS. The vari-angle cone mirror 51 of this embodiment is equivalent to the transmission optical system 21.
The conical portion 52 that reflects the laser light from the lens and the conical portion 53 that reflects the laser light from the angle detection optical system 22 are concentrically separated. Conical portion 5 for transmission optics 21
2 similarly to the vari-angle cone mirror 28 shown in FIGS. 6 to 8 and the like, the apex angle of the conical surface 52a gradually changes in the circumferential direction, and the apex angle of the conical surface 52a is changed to one position in the circumferential direction. It is a shape in which the step portion 52c is formed due to the discontinuity. The conical portion 53 for the angle detection optical system 22 is formed around the conical portion 52, and similarly, the apex angle of the conical surface 53a gradually changes in the circumferential direction so that the conical surface 53a is apex at one position in the circumferential direction. The shape is such that a step portion 53c is formed due to the discontinuity of the corners.

As shown in FIG. 11, FIG. 12 or FIG. 13, FIG. 14, a step portion formed in one round of the conical surface as the apex angle gradually changes in the circumferential direction is formed in the circumferential direction. It is also conceivable to form two or more places. 12,
The vari-angle cone mirror 61 shown in FIG.
c and 61'c are formed at two locations, and have two conical surfaces 61a and 61'a that are divided in half in the circumferential direction. In this example, the minimum value and the maximum value of the apex angle are both conical surfaces 61a, 6a.
1'a is common. Note that the conical axis is designated by reference numeral 61b.
Indicate. Therefore, this Bali angle cone mirror 6
By rotating 1 once, it is possible to perform similar scanning of the transmitted light twice.

In the vari-angle cone mirror 71 shown in FIGS. 13 and 14, stepped portions 71c and 71'c are formed at two locations, and two conical surfaces 71 are divided into halves in the circumferential direction.
a and 71'a are similar to the above, but the maximum value of the apex angle of one conical surface 71a is larger than the other conical surface 71'a.
The minimum value of the vertical angle of is larger. In addition, the conical axis is denoted by reference numeral 7
Shown as 1b. Therefore, when the transmitted light is scanned by the vari-angle cone mirror 71, one rotation of the vari-angle cone mirror 71 scans two areas spaced in the scanning direction.

The reflecting mirror of the present invention is not limited to the transmitting optical system of a laser radar, but may be applied as a reflecting mirror of a transmitting optical system in a shape detecting device for detecting the shape of an object by image processing using a television camera, for example. it can. The configuration of the transmission optical system in this case is the same as that shown in FIG. 3 to FIG. 5, etc., and the transmission light transmitted by the transmission optical system projects thin lines arranged at equal intervals on the surface of the object. . The television camera picks up the image and detects the surface shape of the object by image processing. In this case, if the surface of the object is a plane, the projected fine line remains a straight line. However, if the surface of the object is uneven, the straight line will be distorted. Based on this distortion, the surface shape of the object is detected by image processing.

Further, the reflecting mirror of the present invention is not limited to the case of scanning the transmission light as in the above-mentioned transmission optical system, but may be used in various other cases, for example, the case of being used without being rotated. In this case, the light projected from the surroundings is reflected by changing the reflection direction according to the apex angle.

[0019]

According to the present invention, since the conical surface whose apex angle gradually changes in the circumferential direction is used as the reflecting surface, it becomes possible to give a reflection direction change which has not been heretofore available. When used as a reflecting mirror for scanning transmitted light, scan linearity of transmitted light can be easily realized.

According to the second aspect, since there are a plurality of step portions formed on the conical surface, it is possible to give a complicated change in the reflection direction in one rotation of the reflecting mirror.

According to the third aspect, since the plurality of conical surfaces are concentrically formed, it is easy to set the apex angle of each conical surface.

[Brief description of drawings]

FIG. 1 is a plan view showing an internal structure of a laser radar using a reflecting mirror of an embodiment of the present invention in a transmission optical system.

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 view showing a reflecting mirror according to an embodiment of the present invention, and FIG.
3 is an enlarged view of a reflecting mirror in FIG.

FIG. 7 is a left side view of FIG.

FIG. 8 is a perspective view of the reflecting mirror.

FIG. 9 is a front view showing another embodiment of the reflecting mirror of the present invention.

FIG. 10 is a left side view of FIG.

FIG. 11 is a front view showing still another embodiment of the reflecting mirror of the present invention.

FIG. 12 is a left side view of FIG. 11.

FIG. 13 is a front view showing still another embodiment of the reflecting mirror of the present invention.

FIG. 14 is a left side view 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, 61, 71 Variangle Cone Mirror (Reflecting Mirror) 52 Transmission Cone part for light 53 Cone part for angle detection 28a, 52a, 53a, 61a, 61'a, 71a,
71'a conical surface 28b, 51b, 61b, 71b conical axis 28c, 52c, 53c, 61c, 61'c, 71c,
71'c step

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

Claims (3)

[Claims] 1. A reflector having a conical surface whose apex angle gradually changes in the circumferential direction as a reflecting surface. 2. The reflection according to claim 1, wherein a plurality of stepped portions are formed in the circumferential direction in one round of the conical surface as the apex angle gradually changes in the circumferential direction. mirror. 3. A reflecting mirror having a common conical axis and a plurality of concentric conical surfaces whose apex angle gradually changes in the circumferential direction.