JP2007078516A - Laser radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser radar system capable of detecting a distance to an object or the like by irradiating the object with a laser beam. <P>SOLUTION: This laser radar system comprises: a polarization beam splitter 4 for transmitting the laser beam and for polarization-reflecting the laser beam polarized by 90°; a low-reflection mirror 6 provided in a focusing point of a focus lens 5; an irradiation lens 7 for converting the laser beam into a scanning laser beam of a substantially parallel beam for irradiating the object; a 1/4 wavelength plate 10 arranged in an optical path between the low-reflection mirror 6 and the object; a photodetector 12 for a servo provided in a position irradiated with a reflected laser beam for the servo reflected by the low-reflection mirror 6, via the focus lens 5, a polarization beam splitter 3 and the polarization beam splitter 4; and a signal detecting photodetector 14 provided in a position where a reflected scanning laser beam reflected from the object is reflected by the polarization beam splitter 4 to be emitted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser radar device that irradiates an object with laser light and recognizes the distance to the object, the position of the object, and the like using the laser light reflected and returned from the object.

  Recently, vehicles equipped with a device that detects the distance, relative speed, position, and the like between a vehicle traveling in front of the vehicle and irradiating it with laser light have been commercialized. The device is called a laser radar device.

Such a laser radar apparatus irradiates laser light emitted from a laser diode in the direction of an object and moves the irradiation direction of the laser light in the vertical and horizontal directions, so-called scanning, within a predetermined range. Thus, it is configured to obtain information on the object (see, for example, Patent Document 1).
JP 11-94945 A

  In the technique described in Patent Document 1, an optical system that irradiates an object with laser light and an optical system that receives laser light reflected from the object are separately provided. It is disadvantageous for downsizing. Further, since the irradiation position of the laser light and the light receiving position of the reflected light are different, there is a problem that the amount of the received reflected light is reduced and the sensitivity is lowered.

  The present invention seeks to provide a laser radar device that can solve such problems.

  The present invention includes a first polarizing beam splitter that receives laser light emitted from a laser diode that emits laser light and transmits and reflects the incident laser light, and is reflected by the first polarizing beam splitter. A second polarization beam splitter that transmits unpolarized laser light that is incident upon the laser beam and reflects laser light that is polarized by 90 degrees with respect to the laser light and that is incident from the opposite direction; A laser beam that has passed through the second polarizing beam splitter is incident and a focus lens that forms an image of the laser beam at a focal point; A low-reflection mirror that reflects laser light and transmits most of the laser light, and the low-reflection mirror An irradiation lens on which the reflected laser beam is incident, and the laser beam is converted into a scanning laser beam that is substantially parallel light that irradiates the object and the reflected laser beam for scanning reflected from the object is incident A quarter-wave plate disposed in the optical path between the low-reflection mirror and the object, and the reflected laser beam for servo reflected by the low-reflection mirror, the focus lens and the second polarization beam splitter And a servo photodetector provided at a position irradiated through the first polarizing beam splitter, and a reflected scanning laser beam incident on the irradiation lens and transmitted through the low reflection mirror and the focus lens. And a signal detection photodetector provided at a position where the signal laser beam reflected by the second polarization beam splitter is irradiated. And it is configured so as to change the irradiation direction of the scanning laser beam by displacing in a direction perpendicular to the optical axis's.

  Further, the present invention is configured to control the irradiation direction of the scanning laser light according to the irradiation position of the servo reflected laser light irradiated to the servo light detector.

  The present invention changes the radiation direction of the laser beam for scanning by displacing the focus lens in the X direction and the Y direction which are perpendicular to each other, and changes the X direction and the Y direction based on the signal obtained by the servo photodetector. It is configured to control the position of the direction.

  In addition, the present invention uses a quadrant sensor composed of four ABCD sensor units as a servo photodetector, and signals obtained from two sets of sensors arranged corresponding to the X and Y directions. The position in the X direction and the Y direction is recognized based on the difference signal that is the difference between the two.

  And this invention is comprised so that a quarter wavelength plate may be arrange | positioned in the optical path between an irradiation lens and a target object.

  Furthermore, the present invention is configured so that the quarter-wave plate is disposed in the optical path between the low reflection mirror and the irradiation lens.

  In the present invention, an antireflection film is formed on the surface of the low reflection mirror on the irradiation lens side.

  And the low reflection mirror of this invention is comprised with the glass plate or the resin plate.

  Further, the present invention is configured so that the quarter-wave plate and the low reflection mirror are integrally disposed in the optical path.

  Furthermore, the present invention is configured to form an antireflection film on the surface of the quarter-wave plate on the irradiation lens side.

  The present invention also provides a laser beam for scanning by a displacement operation of the focus lens by providing a collimating lens for converting the laser beam into a substantially parallel beam in the optical path for guiding the laser beam emitted from the laser diode to the first polarization beam splitter. The displacement control operation can be accurately performed.

The present invention includes a first polarizing beam splitter that receives laser light emitted from a laser diode that emits laser light and transmits and reflects the incident laser light, and is reflected by the first polarizing beam splitter. A second polarization beam splitter that transmits unpolarized laser light that is incident upon the laser beam and reflects laser light that is polarized by 90 degrees with respect to the laser light and that is incident from the opposite direction; A laser beam that has passed through the second polarizing beam splitter is incident and a focus lens that forms an image of the laser beam at a focal point; A low-reflection mirror that reflects laser light and transmits most of the laser light, and the low-reflection mirror An irradiation lens on which the reflected laser beam is incident, and the laser beam is converted into a scanning laser beam that is substantially parallel light that irradiates the object and the reflected laser beam for scanning reflected from the object is incident A quarter-wave plate disposed in the optical path between the low-reflection mirror and the object, and the reflected laser beam for servo reflected by the low-reflection mirror, the focus lens and the second polarization beam splitter And a servo photodetector provided at a position irradiated through the first polarizing beam splitter, and a reflected scanning laser beam incident on the irradiation lens and transmitted through the low reflection mirror and the focus lens. And a signal detection photodetector provided at a position where the signal laser beam reflected by the second polarization beam splitter is irradiated. The scanning laser beam is reflected from the object by the irradiation lens that irradiates the scanning laser beam because the irradiation direction of the scanning laser beam is changed by displacing the lens in the direction perpendicular to the optical axis. Since the light is received, not only can the laser radar device be miniaturized, but also the amount of reflected light received is not reduced, so that the sensitivity can be increased.

  Further, in the present invention, since the irradiation lens to which the laser light imaged by the focus lens is incident is provided, and the scanning laser light is generated by the irradiation lens, the diameter and refractive index of the irradiation lens By selecting, the irradiation angle of the scanning laser beam can be increased. Therefore, according to the present invention, the irradiation range of the scanning laser beam can be expanded.

  In the present invention, a low-reflection mirror that reflects a part of the laser light at the focal point formed by the focus lens and transmits a part of the laser light is provided and reflected by the low-reflection mirror. The servo light detector is provided at the position where the reflected laser light for servo is irradiated, and the irradiation direction of the scanning laser light is controlled by the position of the laser light irradiated to the servo light detector. The lens position control operation can be performed accurately.

  Further, the present invention changes the radiation direction of the scanning laser beam by displacing the focus lens in the X direction and the Y direction which are perpendicular to each other, and changes the X direction and the Y direction based on the signal obtained by the servo photodetector. Since the position of the direction is controlled, the position control operation of the focus lens can be easily performed.

  In the present invention, a quadrant sensor composed of four ABCD sensor units is used as a servo photodetector, and signals obtained from two sets of sensors arranged corresponding to the X and Y directions. Since the position in the X direction and the Y direction is recognized based on the difference signal that is the difference between the two, the detection mechanism is simplified.

  In the present invention, since a collimating lens for converting laser light into substantially parallel light is provided in the optical path between the laser diode and the polarization beam splitter, scanning is performed even if the position of the focus lens in the optical axis direction changes. There is little effect on the operation of changing the irradiation direction of the laser beam. Therefore, the present invention has an advantage that an accurate laser light irradiation operation can be performed even if the device is mounted on a device that receives vibration, such as a car.

  The present invention is configured so that the displacement operation in the irradiation direction of the laser light emitted from the laser diode is performed using the displacement operation of the lens.

  FIG. 1 is a schematic diagram showing a laser radar device of the present invention, FIG. 2 is a block circuit diagram showing the laser radar device of the present invention, and FIG. 3 is a diagram for explaining the operation of the present invention.

  In FIG. 1, 1 is a laser diode that emits laser light L, 2 is a collimating lens that receives the laser light L emitted from the laser diode 1 and converts the laser light L into substantially parallel laser light L1. Reference numeral 3 denotes a first polarization beam splitter on which the laser beam L1 is incident, and has a function of transmitting part of the laser beam and reflecting most of the laser beam as the laser beam L2.

4 is provided at a position where the laser beam L2 reflected by the first polarization beam splitter 3 is incident, is inclined by 45 degrees with respect to the optical path, and transmits the laser beam L2. The polarizing beam splitter has a function of reflecting laser light polarized by 90 degrees with laser light incident from the opposite side of the incident direction of the laser light L2 and transmitting unpolarized laser light.

  Reference numeral 5 denotes a focus lens on which the laser beam L2 transmitted through the second polarizing beam splitter 2 is incident and forms an image on the focal point P, and is fixedly supported by the lens holder H shown in FIG. The lens holder H is provided so as to be displaceable in a plane perpendicular to the optical axis by a lens holder holding mechanism (not shown).

  Reference numeral 6 denotes a low-reflection mirror which is disposed so as to be perpendicular to the central axis of the focus lens 5 and which is provided on the focal point P of the focus lens 5. Most of the laser light is transmitted as laser light L3 and a part thereof is reflected as servo reflected laser light L5.

  Reference numeral 7 denotes an irradiation lens composed of a first lens 8 and a second lens 9, and a laser beam L3 that has passed through the low-reflection mirror 6 is incident thereon, and the laser beam L3 is a substantially parallel beam. It is configured to convert to L5.

  Reference numeral 10 denotes a quarter-wave plate disposed in the optical path of the scanning laser light L5 emitted from the irradiation lens 7 to the object, and acts to circularly polarize the scanning laser light L5 from linearly polarized light. The scanning reflected laser beam L6 reflected from the object is linearly polarized from circularly polarized light.

  Reference numeral 11 denotes a servo condensing lens on which the servo reflected laser light L4 reflected from the low reflection mirror 6 passes through the focus lens 5, the second polarizing beam splitter 4, and the first polarizing beam splitter 3, and 12 Is a servo photodetector provided at a position where the servo reflected laser beam L4 condensed by the servo condenser lens 11 is irradiated. As shown in FIG. 2, A, B, C, and It consists of four sensor parts of D.

  In FIG. 13, the scanning reflected laser beam L 6 reflected from the object is incident on the second polarizing beam splitter 4 through the quarter-wave plate 10, the irradiation lens 7, the low-reflection mirror 6, and the focus lens 5. The signal condensing lens on which the signal laser light L7 reflected by the polarization reflection operation of the two-polarization beam splitter 4 is incident, and the signal laser light L7 collected by the signal condensing lens 13 are irradiated to the signal condensing lens 14. It is a signal detection photodetector provided at a position, and is configured to be able to perform detection operations such as the distance to the object and the moving speed of the object based on the detection output.

  In such a configuration, the laser light L emitted from the laser diode 1 is converted into the parallel light L1 by the collimator lens 2 and then reflected by the first polarization beam splitter 3 to be converted into the second polarization beam splitter 4 as the laser light L2. Is incident on. Since the laser beam L2 incident on the second polarization beam splitter 4 is not polarized, it passes through the second polarization beam splitter 4 and enters the focus lens 5. The laser light L2 incident on the focus lens 5 is incident on the low reflection mirror 6 after passing through the focus lens 5. Most of the laser light L2 incident on the low reflection mirror 6 is transmitted as laser light L3, and a part thereof is reflected as servo reflected laser light L4.

The laser light L3 that has passed through the low reflection mirror 6 is incident on the irradiation lens 7 and is irradiated by the irradiation lens 7 as scanning laser light L5 that is substantially parallel light.
When the focus lens 5 is displaced from the position indicated by the solid line to the position indicated by the broken line, the irradiation direction of the scanning laser light L5 and the reflection direction of the servo reflected laser light are changed from the optical path indicated by the solid line to the optical path indicated by the broken line. .

  As is clear from this operation, the irradiation direction of the scanning laser light L5 can be changed by displacing the focus lens 5 in the direction perpendicular to the optical axis. The change operation of the irradiation direction shown in FIG. 1 explains the change operation in the vertical direction that is the X direction. However, when the focus lens 5 is displaced in the direction perpendicular to the paper surface, the irradiation lens 7 emits light. The irradiation direction of the scanning laser light L5 can be changed to the left-right direction which is the Y direction.

  The scanning laser light L5 irradiated through the irradiation lens 7 passes through the quarter-wave plate 10 and is irradiated onto the object. When the scanning laser beam L5 applied to the object is irradiated on a right-angle reflecting surface that is perpendicular to the optical axis, the scanning laser light L5 is reflected from the right-angle reflecting surface of the object and scanned. The reflected laser beam L6 is reflected in the direction opposite to the irradiation direction of the scanning laser beam L5.

  The scanning reflected laser light L6 reflected from the object is incident on the irradiation lens 7 through the quarter-wave plate 10, and the scanning reflected laser light L6 is polarized by the quarter-wave plate 10. The laser beam is linearly polarized from circularly polarized light by the action.

  The scanning reflected laser beam L6 linearly polarized by the quarter-wave plate 10 is incident on the focus lens 5 through the low reflection mirror 6 provided on the focal point P by the irradiation lens 7. become. The reflected scanning laser beam L6 incident on the focus lens 5 is transmitted through the focus lens 5 and then incident on the second polarization beam splitter 4.

  The scanning reflected laser beam L6 incident on the second polarization beam splitter 4 is converted into a laser beam polarized by 90 degrees by reciprocating through the quarter-wave plate 10, so that the second The light is reflected as the signal laser beam L 7 by the polarization reflection action of the polarization beam splitter 4 and is incident on the signal condenser lens 13. Since the signal laser beam L7 incident on the signal condenser lens 13 is irradiated to the signal detection photodetector 14 by the condensing action of the signal condenser lens 13, the signal detection photodetector 14 is applied. Can obtain information on the object, such as distance to the object, moving speed of the object, and shape of the object. By obtaining such information, the operation as a laser radar device can be performed.

  As described above, the laser light L emitted from the laser diode 1 is reflected by the first polarization beam splitter 3 and then enters the irradiation lens 7 through the second polarization beam splitter 4, the focus lens 5 and the low reflection mirror 6. Is done. The laser beam L3 incident on the irradiation lens 7 is converted into a scanning laser beam L5 that is substantially parallel light by the irradiation lens 7 and then irradiated onto the object through the quarter-wave plate 10.

  The laser light L emitted from the laser diode 1 in this way is irradiated as the scanning laser light L5 in the direction of the object, but the focus lens 5 is directed in the X direction perpendicular to the optical axis, that is, up and down. By displacing in the direction and the Y direction, that is, in the left-right direction, the scanning laser beam L5 can be displaced in the up-down direction and the left-right direction.

  Therefore, for example, as shown in FIG. 3, an operation of displacing the irradiation position of the scanning laser beam L5 in the order of a → b → c → d → e → f → g → h → i → j, that is, a so-called scanning operation is performed. This can be done by controlling the displacement of the lens 5 in the X and Y directions.

  By the above-described operation, the irradiation operation and the scanning operation of the scanning laser light L5 toward the object are performed, and the scanning laser light L5 irradiated in this way is reflected from the object and the reflected laser light for scanning. L6 enters the irradiation lens 7 through the quarter-wave plate 10. The scanning reflected laser light L6 incident on the irradiation lens 7 passes through the low reflection mirror 6 and the focus lens 5 as described above, and then enters the second polarization beam splitter 4. The scanning reflected laser light L6 incident on the second polarizing beam splitter 4 is incident on the signal condensing lens 13 as signal laser light L7 by the polarization reflection action of the second polarizing beam splitter 4, and the signal collecting light. The light detecting unit 14 irradiates the signal detecting photodetector 14 with the condensing operation of the optical lens 13.

  By changing the irradiation position of the scanning laser beam L5 as described above, it is possible to irradiate the scanning laser beam L5 to the target object within the displacement range, so that the scanning reflection reflected from the target object is performed. The signal detection light detector 14 is irradiated with the laser light L6 as the signal laser light L7, and information such as the position, size and moving speed of the object is obtained from the signal obtained from the signal detection light detector 14. I can do it.

  On the other hand, the servo reflected laser light L4 reflected from the low reflection mirror 6 is incident on the second polarization beam splitter 4 through the focus lens 5, and the servo reflected laser light L4 is a quarter. Since the wave plate 10 is not transmitted, the diffraction direction is not polarized. Therefore, the reflected laser beam L4 for servo is not reflected by the second polarizing beam splitter 4, but is transmitted as it is and is incident on the first polarizing beam splitter 3.

  The servo reflected laser light L4 incident on the first polarizing beam splitter 3 passes through the first polarizing beam splitter 3 and is condensed by the servo condensing lens 11 to the servo photodetector 12. Irradiated. Therefore, the position control operation of the focus lens 5 can be performed based on the signal obtained from the servo photodetector 12.

  Next, the position control operation of the focus lens 5 will be described with reference to the block circuit diagram shown in FIG.

  In FIG. 2, reference numeral 15 denotes a first I / V converter that converts a current, which is a signal obtained from the sensor part A constituting the servo photodetector 12, into a voltage, and 16 denotes a current, which is a signal obtained from the sensor part B. Is a second I / V converter that converts the current into a voltage, 17 is a third I / V converter that converts a current that is a signal obtained from the sensor unit C into a voltage, and 18 is a voltage that is a signal obtained from the sensor unit D. It is the 4th I / V converter which converts into.

  Reference numeral 19 denotes a first low-pass filter that blocks a pulse component included in the signal converted into a voltage by the first I / V converter 15, and reference numeral 20 denotes a signal converted into a voltage by the second I / V converter 16. A second low-pass filter that cuts off the included pulse component, 21 is a third low-pass filter that cuts off the pulse component contained in the signal converted into a voltage by the third I / V converter 17, and 22 is the fourth I / V. It is a fourth low-pass filter that blocks a pulse component included in the signal converted into a voltage by the converter 18.

Reference numeral 23 denotes a first addition circuit that adds a signal that has passed through the first low-pass filter 19, that is, a signal obtained from the sensor unit A, and a signal that has passed through the fourth low-pass filter 22, that is, a signal obtained from the sensor unit D. 24 is a second addition circuit for adding the signal that has passed through the second low-pass filter 20, that is, the signal obtained from the sensor unit B, and the signal that has passed through the third low-pass filter 21, that is, the signal obtained from the sensor unit C; 25 is a third addition circuit for adding the signal that has passed through the first low-pass filter 19, that is, the signal obtained from the sensor unit A, and the signal that has passed through the second low-pass filter 20, that is, the signal obtained from the sensor unit B; Reference numeral 26 denotes a signal that has passed through the third low-pass filter 21, that is, a signal obtained from the sensor unit C and the fourth low-pass filter. Signal passed through 2, that is, the fourth adder circuit for adding the signal obtained from the sensor unit D.

  Reference numeral 27 denotes a first comparison circuit to which the output signal of the first addition circuit 23 and the output signal of the second addition circuit 24 are input, and is configured to output a signal based on a level difference between the input signals. Yes. That is, the signal output from the first comparison circuit 27 is obtained by adding the signals obtained from the sensor unit A and the sensor unit D constituting the servo photodetector 12 and the sensor unit B and the sensor unit C. The level of the output signal changes according to the irradiation position of the spot S of the reflected laser beam L4 for irradiation on the servo photodetector 12.

  That is, in the servo photodetector 12, if the spot S is shifted to the left side (in FIG. 2) of the dividing line V that divides the sensor parts A and D and the sensor parts B and C, the first addition circuit Since the level of the output signal 23 is higher than the level of the output signal of the second adder circuit 24, the level of the output signal of the first comparison circuit 27 is increased to the + side. On the other hand, when the spot S is shifted to the right side (in FIG. 2) of the dividing line V that divides the sensor parts A and D and the sensor parts B and C, the level of the output signal of the second adder circuit 24 is Since it becomes higher than the level of the output signal of the first addition circuit 23, the level of the output signal of the first comparison circuit 27 becomes larger on the negative side.

  The level of the output signal of the first comparison circuit 27 changes corresponding to the position of the spot S. The level change is caused by the scanning laser light accompanying the displacement of the focus lens 5 in the X direction. It is configured to correspond to the amount of displacement in the X direction of L5, that is, the vertical direction.

  Reference numeral 28 denotes a second comparison circuit to which the output signal of the third addition circuit 25 and the output signal of the fourth addition circuit 26 are input, and is configured to output a signal based on a level difference between the input signals. Yes. That is, the signal output from the second comparison circuit 28 is obtained from the signal obtained by adding the signals obtained from the sensor unit A and the sensor unit B constituting the servo photodetector 12 and from the sensor unit C and the sensor unit D. The level of the output signal changes according to the irradiation position of the spot S of the reflected laser beam L4 for irradiation on the servo photodetector 12.

  That is, when the spot S is shifted above the dividing line H that divides the sensor parts A and B and the sensor parts C and D in the servo photodetector 12 (in FIG. 2), the third adder circuit Since the level of the output signal 25 becomes higher than the level of the output signal of the fourth adder circuit 26, the level of the output signal of the second comparison circuit 28 increases to the + side. On the contrary, when the spot S is shifted below the dividing line H that divides the sensor parts A and B and the sensor parts C and D (in FIG. 3), the level of the output signal of the fourth addition circuit 26 Becomes larger than the level of the output signal of the third adder circuit 25, the level of the output signal of the second comparator circuit 28 becomes larger to the negative side.

  The level of the output signal of the second comparison circuit 28 changes corresponding to the position of the spot S. The level change is caused by the scanning laser light accompanying the displacement of the focus lens 5 in the Y direction. It is configured to correspond to the amount of displacement in the Y direction of L5, that is, the left-right direction.

  Reference numeral 29 denotes a control circuit that controls the control operation with respect to the irradiation direction of the scanning laser beam L5 and the irradiation operation of the laser diode 1, and 30 denotes a laser drive circuit whose operation is controlled by the control circuit 29. It serves to supply a drive signal.

  Reference numeral 31 denotes an X position instruction signal generation circuit whose operation is controlled by the control circuit 29. Based on the control signal output from the control circuit 29, the X position of the scanning laser beam L5, that is, the vertical position is indicated. It is comprised so that the signal to perform may be output. Reference numeral 32 denotes a Y position instruction signal generation circuit whose operation is controlled by the control circuit 29. Based on the control signal output from the control circuit 29, the Y position of the scanning laser light L5, that is, the position in the left-right direction is indicated. It is comprised so that the signal which carries out may be output.

  Reference numeral 33 denotes an X-direction servo circuit to which the output signal of the first comparison circuit 27 and the signal output from the X-position indication signal generation circuit 31 are input, and a servo signal in a direction that eliminates a level difference between the input signals. It is configured to generate and output. Reference numeral 34 denotes a Y-direction servo circuit to which the output signal of the second comparison circuit 28 and the signal output from the Y-position indication signal generation circuit 32 are input, and a servo signal in a direction that eliminates the level difference between the input signals. It is configured to generate and output.

  Reference numeral 35 denotes an X-direction drive coil drive circuit that supplies a drive signal to the X-direction drive coil 36 attached to the lens holder H. The drive signal is generated based on the servo signal output from the X-direction servo circuit 33. It is configured to supply. Reference numeral 37 denotes a Y-direction drive coil drive circuit for supplying a drive signal to a Y-direction drive coil 38 attached to the lens holder H. The drive signal is based on the servo signal output from the Y-direction servo circuit 34. It is configured to supply.

  Reference numeral 39 denotes a fifth I / V converter that converts a current, which is a signal obtained from the signal detection photodetector 14, into a voltage, and is configured to output a signal obtained from the scanning reflected laser light L6 as an electrical signal. Has been.

  Reference numeral 40 denotes a received signal processing circuit to which a signal converted into a voltage signal by the fifth I / V converter 39 is input, and is configured to perform a demodulating operation or the like of the input signal. 41 is an information signal processing circuit to which the signal demodulated by the received signal processing circuit 40 is input, and displays various data by extracting information such as distance to the object, relative speed and shape. The device 42 is configured to be displayed.

  As described above, the operation control circuit of the laser radar apparatus of the present invention is configured. Next, the control operation will be described. When a control signal for setting the position of the scanning laser light L5 in the X direction to X1 is output from the control circuit 29 to the X position instruction signal generation circuit 31, the X position instruction signal generation circuit 31 outputs a nonvolatile memory. Based on data stored in (not shown), an operation is performed in which an instruction signal for setting the scanning laser beam L5 to the X1 position is output to the X-direction servo circuit 33.

  Further, a control signal for the laser drive circuit 30 is output from the control circuit 29, and a pulsed drive signal is supplied from the laser drive circuit 30 to the laser diode 1. When such a drive signal is supplied to the laser diode 1, the laser light L is emitted from the laser diode 1.

  In the embodiment shown in FIG. 1, the laser light L emitted from the laser diode 1 is reflected by the first polarizing beam splitter 3 and then enters the focus lens 5 through the second polarizing beam splitter 4. The laser beam L2 incident on the focus lens 5 is irradiated onto the low-reflection mirror 6 by the focusing operation by the focus lens 5. Most of the laser beam L2 is transmitted as the laser beam L3, and a part thereof is reflected for servo. Reflected as laser light L4.

  The laser beam L3 that has passed through the low reflection mirror 6 enters the irradiation lens 7, is converted into a scanning laser beam L5 that is substantially parallel light by the irradiation lens 7, and passes through the quarter-wave plate 10 to obtain an object. Will be irradiated.

  On the other hand, the servo reflected laser beam L4 reflected by the low reflection mirror 6 passes through the focus lens 5, the second polarizing beam splitter 4 and the first polarizing beam splitter 3, and then collected by the servo condensing lens 11. The light is irradiated onto the servo photodetector 12 by an optical operation. On the servo light detector 12, the irradiation position of the servo reflected laser beam L4 is represented as a spot S as shown in FIG.

  Since the servo light detector 12 is composed of the four-divided sensor portions A, B, C, and D as described above, the detection signal corresponding to the irradiation position of the spot S is sent to the low-pass filters 19, 20, 21 and 22 are output. When such detection signals are output from the low-pass filters 19, 20, 21, and 22, the respective signals are output from the first addition circuit 23, the second addition circuit 24, the third addition circuit 25, and the fourth addition circuit 26. After the addition, it is input to the first comparison circuit 27 and the second comparison circuit 28.

  From the first comparison circuit 27, as described above, a signal corresponding to the displacement position in the X direction of the scanning laser beam L5, that is, a signal of (A + D)-(B + C) is output and input to the X direction servo circuit 33. Is done. Here, A, B, C, and D represent signal levels obtained by the sensor units A, B, C, and D, respectively.

  On the other hand, the X-direction servo circuit 33 outputs the signal indicating the X1 position from the X-position instruction signal generation circuit 31 as described above, so that the spot S corresponds to the X1 position from the X-direction servo circuit 33. A servo signal for displacing to the position is output to the X direction drive coil drive circuit 35.

  When such a servo signal is input to the X direction drive coil drive circuit 35, the drive signal is supplied from the X direction drive coil drive circuit 35 to the X direction drive coil 36. When such a signal is supplied to the X-direction drive coil 36, the focus lens 5 is caused to cooperate by a magnetic force induced in the X-direction drive coil 36 and a magnetic force generated from a magnet (not shown). It is displaced in the X direction. Then, such a displacement operation in the X direction is performed so as to displace the spot S to a position corresponding to the position of X1. As a result of such servo operation, a control operation for setting the position of the spot S to the X1 position, that is, a control operation for irradiating the X1 position with the scanning laser beam L5 is performed. Therefore, the operation for displacing and holding the scanning laser beam L5 at the position X1 can be performed based on the position determination signal in the X direction output from the control circuit 29.

  As described above, the operation for displacing the scanning laser beam L5 to the desired position in the X direction, that is, the vertical direction is performed. Next, the scanning laser beam L5 is displaced to the desired position in the Y direction, that is, the horizontal direction. The operation will be described.

  When a control signal for setting the Y-direction position of the scanning laser beam L5 to Y1 is output from the control circuit 29 to the Y position instruction signal generation circuit 32, the Y position instruction signal generation circuit 32 is non-volatile. An instruction signal for setting the scanning laser beam L5 to the Y1 position based on data stored in a memory (not shown) is output to the Y-direction servo circuit 34.

Further, a control signal for the laser drive circuit 30 by the control circuit 29 is output, and a drive signal is supplied from the laser drive circuit 30 to the laser diode 1. When such a drive signal is supplied to the laser diode 1, the laser light L is emitted from the laser diode 1. The laser light L emitted from the laser diode 1 is reflected by the first polarizing beam splitter 3 and then enters the focus lens 5 through the second polarizing beam splitter 4. The laser beam L2 incident on the focus lens 5 is irradiated onto the low-reflection mirror 6 by the focusing operation by the focus lens 5. Most of the laser beam L2 is transmitted as the laser beam L3, and a part thereof is reflected for servo. Reflected as laser light L4.

  The laser beam L3 that has passed through the low reflection mirror 6 enters the irradiation lens 7, is converted into a scanning laser beam L5 that is parallel light by the irradiation lens 7, and passes through the quarter-wave plate 10 to the object. Will be irradiated.

  On the other hand, the servo reflected laser beam L4 reflected by the low reflection mirror 6 passes through the focus lens 5 and the polarization diffraction beam splitter 2 and then is irradiated to the servo photodetector 12. On the servo light detector 12, the irradiation position of the servo reflected laser light L3 is represented as a spot S as shown in FIG.

  Since the servo light detector 12 is composed of the four-divided sensor portions A, B, C, and D as described above, the detection signal corresponding to the irradiation position of the spot S is sent to the low-pass filters 19, 20, 21 and 22 are output. When such detection signals are output from the low-pass filters 19, 20, 21, and 22, the respective signals are output from the first addition circuit 23, the second addition circuit 24, the third addition circuit 25, and the fourth addition circuit 26. After the addition, it is input to the first comparison circuit 27 and the second comparison circuit 28.

  From the second comparison circuit 28, as described above, a signal corresponding to the displacement position of the scanning laser beam L5 in the Y direction, that is, a signal of (A + B) − (C + D) is output and input to the Y direction servo circuit 34. Is done.

  On the other hand, since the Y-direction servo circuit 34 outputs the signal indicating the Y1 position from the Y-position instruction signal generation circuit 32 as described above, the Y-direction servo circuit 34 corresponds the spot S to the Y1 position. A servo signal for displacing to the position is output to the Y-direction drive coil drive circuit 37.

  When such a servo signal is input to the Y-direction drive coil drive circuit 37, a drive signal is supplied from the Y-direction drive coil drive circuit 37 to the Y-direction drive coil 38. When such a signal is supplied to the Y-direction drive coil 38, the focus lens 5 is displaced in the Y direction by the cooperation of the magnetic force induced in the Y-direction drive coil 38 and the magnetic force generated from the magnet. It is done. Then, such a displacement operation in the Y direction is performed so that the spot S is displaced to a position corresponding to the position of Y1.

  As a result of such a servo operation, a control operation for setting the position of the spot S to the Y1 position, that is, a control operation for irradiating the Y1 position with the scanning laser beam L5 is performed. Therefore, the operation for displacing and holding the scanning laser beam L5 at the position Y1 can be performed based on the position determination signal in the Y direction output from the control circuit 29.

  As described above, when the signal for determining the position in the X direction and the Y direction output from the control circuit 29 is output, the control operation for moving the scanning laser light L5 to the specified position is displaced. This can be done according to the operation. Therefore, for example, as shown in FIG. 3, the control operation for displacing the irradiation position of the scanning laser beam L1 in the order of a → b → c → d → e → f → g → h → i → j is performed. Can be performed by controlling displacement.

  As described above, an operation for displacing the scanning laser beam L5 in the X direction and the Y direction, which are predetermined ranges, that is, a scanning operation is performed. When such an operation is performed, the scanning laser beam L5 is within the predetermined range. Laser light reflected from a certain object is incident on the irradiation lens 7 through the quarter-wave plate 10 as reflected scanning laser light L6.

  The scanning reflected laser light L6 incident on the irradiation lens 7 is irradiated to the second polarization beam splitter 4 through the low reflection mirror 6 and the focus lens 5. As a result, the scanning reflected laser beam L6 irradiated to the second polarizing beam splitter 4 is converted into the signal laser beam L7 by the polarization reflecting operation of the second polarizing beam splitter 4.

  The signal laser light L7 thus converted is condensed by the signal condenser lens 13 and then irradiated to the signal detection photodetector 14. When such signal laser light L7 is irradiated onto the signal detection photodetector 14, a signal obtained from the signal detection photodetector 14 is input to the reception signal processing circuit 40, and a demodulation processing operation is performed. The signal input to the reception signal processing circuit 40 and subjected to the demodulation processing operation is a signal obtained from the reflected laser beam L6 for scanning reflected from the object, and the distance from the object, the relative velocity and the shape. Thus, the information data is demodulated.

  When various signals demodulated by the reception signal processing circuit 40 are input to the information signal processing circuit 41, signal processing operations are performed by the information signal processing circuit 41 and various data are displayed on the display 42. As a result of such an operation, it is possible to perform an operation as a laser radar device that obtains information obtained from an object.

  In the case of performing an operation for changing the irradiation position of the laser beam, the drive signal supplied from the laser driving circuit 30 to the laser diode 1 is generally a pulse signal that is performed while selecting the irradiation timing in order to obtain necessary information. Is. When the light emission driving operation of the laser diode 1 is performed based on the pulse signal, a pulse component is included in the signal obtained from the servo photodetector 12, and in this embodiment, a low pass is used to delete the pulse signal. Filters 19, 20, 21 and 22 are provided.

  Further, as the low reflection mirror 6 used in this embodiment, a glass plate or a resin plate can be used, but it is reflected from the reflection surface of the low reflection mirror 6, that is, the surface facing the focus lens 5. In order to use laser light, an antireflection film is formed on the opposite surface, that is, the surface on the irradiation lens 7 side. By providing such an antireflection film on the surface of the low reflection mirror 6 on the side of the irradiation lens 7, correct reflected light can be obtained as the reflected light L4 for servo used to detect the position of the focus lens 5. The detection operation can be performed accurately.

  In the present embodiment, the quarter-wave plate 10 is disposed between the irradiation lens 7 and the object, but it may be disposed in the optical path between the low reflection mirror 6 and the irradiation lens 7. In this case, the configuration can be simplified by integrally configuring the low reflection mirror 6 and the quarter-wave plate 10. Further, in this case, the reflection characteristic can be improved by providing an antireflection film on the surface of the quarter-wave plate 10 on the irradiation lens 7 side.

  In the present embodiment, the irradiation lens 7 is composed of two lenses, the first lens 8 and the second lens 9, but the number of lenses is not limited and can be variously changed based on the optical design. It will be. The transmittance and reflectance of the first polarizing beam splitter 3, the second polarizing beam splitter 4, and the low reflection mirror 6 are determined by the laser output emitted from the laser diode 1, the distance to the object to be operated as a radar device, and the like. Various settings can be made based on this.

It is the schematic which shows one Example of the laser radar apparatus of this invention. It is a block circuit diagram which shows one Example of the laser radar apparatus of this invention. It is explanatory drawing for demonstrating operation | movement of this invention.

Explanation of symbols

1 Laser diode
2 Collimating lens
3 First polarization beam splitter
4 Second polarization beam splitter
5 Focus lens
6 Low reflection mirror
7 Irradiation Lens 10 1/4 Wave Plate 11 Condensing Lens for Servo 12 Photodetector for Servo 13 Condensing Lens for Signal 14 Photodetector for Signal Detection

Claims (11)

A laser diode that emits laser light, a first polarizing beam splitter that receives the laser light emitted from the laser diode and transmits and reflects the incident laser light, and is reflected by the first polarizing beam splitter A second polarization beam splitter that transmits the laser beam that is incident and transmits the unpolarized laser beam, and reflects the laser beam that is polarized by 90 degrees with respect to the laser beam and that is incident from the opposite direction; A focus lens that makes the laser beam transmitted through the second polarizing beam splitter incident and that forms an image of the laser beam at a focal point; and a focus lens that forms an image with the focus lens and a part thereof A low-reflection mirror that reflects a large amount of laser light and transmits most of the laser light; The laser beam that has passed through the reflection mirror is incident, the laser beam is converted into a scanning laser beam that is substantially parallel light that irradiates the object, and the reflected scanning laser beam that is reflected from the object is incident. An irradiation lens, a quarter-wave plate disposed in an optical path between the low-reflection mirror and the object, and a servo reflected laser beam reflected by the low-reflection mirror; A servo photodetector provided at a position irradiated through the polarizing beam splitter and the first polarizing beam splitter, and a scanning reflection incident on the irradiation lens and transmitted through the low reflection mirror and the focus lens. A signal detection photodetector provided at a position where the signal laser beam reflected by the second polarization beam splitter is irradiated; Laser radar apparatus being characterized in that so as to change the irradiation direction of the scanning laser beam by displacing in a direction perpendicular to the focusing lens with respect to the optical axis. 2. The laser radar device according to claim 1, wherein the irradiation direction of the scanning laser beam is controlled by the irradiation position of the servo reflected laser beam irradiated to the servo photodetector. The radiation direction of the scanning laser light is changed by displacing the focus lens in the X direction and the Y direction which are perpendicular to each other, and the positions in the X direction and the Y direction are controlled by signals obtained by the servo photodetector. The laser radar device according to claim 2, which is configured as described above. A difference signal which is a difference between signals obtained from two sets of sensors arranged corresponding to the X direction and the Y direction, using a quadrant sensor composed of four ABCD sensor units as a photodetector for servo. 4. The laser radar device according to claim 3, wherein positions in the X direction and the Y direction are recognized based on the above. The laser radar device according to claim 1, wherein a quarter-wave plate is disposed in an optical path between the irradiation lens and the object. The laser radar device according to claim 1, wherein the quarter-wave plate is disposed in an optical path between the low reflection mirror and the irradiation lens. 7. The laser radar device according to claim 5, wherein an antireflection film is formed on a surface of the low reflection mirror on the irradiation lens side. 7. The laser radar device according to claim 5, wherein the low reflection mirror is made of a glass plate or a resin plate. 7. The laser radar device according to claim 6, wherein the quarter-wave plate and the low reflection mirror are integrally disposed in the optical path. The laser radar device according to claim 9, wherein an antireflection film is formed on a surface of the quarter-wave plate on the irradiation lens side. 2. The laser radar device according to claim 1, wherein a collimating lens for converting the laser light into substantially parallel light is provided in an optical path for guiding the laser light emitted from the laser diode to the first polarization beam splitter.

Images