JPH10268050A - Laser range finder and tracking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser tracking device capable of utilizing a laser device having small energy per pulse though the number of pulse repetition is high and an average output is great. SOLUTION: Output pulse beams of a laser device 31 are emitted toward a target so as to transmit wedge type optical plates 33, 36 which are rotated on an optical axis, and laser oscillation pulses of the laser device 31 are detected by a detector 42, to start count-up of a counter 40. Reflection beams from the target are received by a laser receiver 39, and the received pulses are output to the counter 40 to stop the count-up of the counter 40, and the count value is fetched out as distance information until the target. Further, rotation angles of the wedge type optical plates 33, 36 are respectively measured by rotation angle measurers 35, 38, and an error angle calculating circuit 41 calculates an error angle made by the target based on a pulse output of the laser receiver 39 and a rotation angle of the wedge type optical plates 33, 36 obtained by rotation angle measures 35, 38 to output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser tracking device and a laser distance measuring device used for a position measuring device for precisely measuring the position of a flying object such as a small missile.

[0002]

2. Description of the Related Art Conventionally, a laser tracking device using a four-element detector as shown in FIG. 8 has been used as a precise position measuring device for a flying object. In FIG. 8, the laser device 1
The beam spread angle of the laser beam emitted from 1 is narrowed by the beam expander 12, and the laser beam is irradiated toward a target (not shown). A part of the laser beam reflected by the target enters the laser receiver 13.

In the laser receiver 13, an optical lens 131 is used.
Is focused on the light receiving surface of the four-element detector 132. As shown in FIG. 9, the four-element detector 132 includes light receiving portions A to D divided into four parts in a cross shape, and the optical lens 131 appropriately spreads a beam to each of the light receiving portions A to D. Focusing as follows.

The outputs of the light receiving sections A to D are amplified by preamplifiers 133 to 136, respectively, and then increase by variable gain amplifiers (PGA) 137 to 1310 in inverse proportion to a count value from a counter 14 described later. Variable amplification. Outputs SA to AD of the respective PGAs 137 to 1310 are supplied to the error angle calculation circuit 15.

On the other hand, the output of the laser device 11 is monitored by a start pulse detector 16. The start pulse detector 16 detects the output timing of the laser beam and sends it to the counter 14. The counter 14 starts counting up according to a detection signal from the start pulse detector 16, stops counting at the timing of the total output obtained by the error angle calculation circuit 15, and outputs the count value as distance information. The count-up value is sequentially sent to PGAs 137 to 1310 and used for gain control.

In the error angle calculation circuit 15, all outputs SA to SD of the PGAs 137 to 1310 are added by a sum operation circuit (Σ) 151. The result of this addition is sent to the counter 14 as described above, and is used to stop counting up.

Further, SA and SB are added by an adder 152, SC and SD are added by an adder 153, and each addition result is subjected to difference processing by a subtractor 154. Divided by output. The calculation result is output as an error angle ε _{EL in the} elevation direction. The calculation formula is shown below. ε _EL = {(SA + SB)-(SC + SD)} / (SA +
SB + SC + SD) On the other hand, SB and SD are added by the adder 156, and SA and S are added.
C is added by the adder 157, and the result of each addition is
8, the sum is calculated by the divider 159.
51 is divided by the output. The calculation result is output as the error angle ε _{AZ in the} azimuth direction. The calculation formula is shown below. ε _AZ = {(SB + SD)-(SA + SC)} / (SA + SB + SC + SD) In other words, this laser tracking device detects reflected light from a target with respect to irradiation of a single laser beam. Distance measurement and angle measurement of the target. The principle of angle measurement is described in, for example, “Pulsed” from pages 22 to 87 of “InfraRed Handbook”.
Also known as Laser Trackers. In this type of laser tracking device, it is necessary to make the beam spread angle larger than the tracking accuracy.

Therefore, in order to obtain a certain distance measurement and angle measurement distance, it is necessary to increase the energy per pulse of the transmission laser light. That is, a laser device having a high pulse repetition rate and a small energy per pulse even if the average output is large has a disadvantage that only a short distance measurement / angle measurement distance can be obtained.

FIG. 10 shows a flying object distance measuring apparatus.
The laser distance measuring device shown in FIG. FIG.
In the above, the pulse laser device 21 emits a pulse beam by being pulse-driven at a constant period, and the laser beam emitted from the laser device 21 is a beam expander 22.
, The beam spread angle is narrowed, and the beam is irradiated toward a target (not shown). A part of the laser beam reflected by the target enters the laser receiver 23.

In the laser receiver 23, a condensing optical system 231
Is focused on the light receiving surface of the beam detector 232. The beam detector 232 detects the light receiving timing of the beam.
Supplied to This counter 24 is a pulse laser device 2
1 receives a pulse beam start timing signal from
The count-up is started at that timing, stopped at the beam receiving timing detected by the beam detector 232, and the count value at that time is output as distance information.

However, in the conventional laser distance measuring device as described above, the accuracy of detecting the target position is limited by the angular accuracy of an angle detecting device such as an image sensor. The distance measurement for a small distant target is subject to this restriction, and is difficult to realize.

[0012]

As described above, in the conventional laser tracking apparatus, the beam divergence angle needs to be larger than the tracking accuracy. To obtain a certain distance measurement / angle measurement distance, The energy per pulse of the transmitted laser light must be increased, and a laser device with a high pulse repetition rate and a small energy per pulse even if the average output is large can obtain only a short distance measurement and angle measurement distance. There was a disadvantage that there was no.

In the conventional laser distance measuring apparatus, the accuracy of detecting a target position is limited by the angle accuracy of an angle detecting device such as an image sensor. Therefore, the beam divergence angle of the laser is about three times the angle accuracy. The distance measurement for a distant small target is limited by this restriction, and is difficult to realize.

The present invention solves the above problems and provides a laser tracking device which can use a laser device having a high pulse repetition rate and a large average output but low energy per pulse. It is an object of the present invention to provide a laser distance measuring apparatus capable of extending a distance measuring distance for a small target.

[0015]

To achieve the above object, a laser tracking device according to the present invention is configured as follows. (1) A laser device that performs a pulse operation at a constant period, a beam expander that narrows the spread angle of a pulse laser beam output from the laser device, and a laser beam that is rotatably disposed on the optical axis of the output beam of the beam expander. First and second wedge-shaped optical plates, rotation driving means for rotating the first and second wedge-shaped optical plates, and first and second wedge-shaped optical plates for measuring rotation angles of the first and second wedge-shaped optical plates. Second rotation angle measuring means, pulse detecting means for detecting a laser oscillation pulse of the laser device, and a detector for detecting reflected light of a laser beam transmitted through the first and second wedge-shaped optical plates And a laser receiver that receives light, converts it into an electric signal, amplifies and outputs the signal, and starts counting up upon receiving a detection signal from the pulse detecting means, and stops counting with a pulse from the laser receiver. And a counter for measuring the distance from the laser device to the target, and an error from the target based on the pulse output of the laser receiver and the rotation angles of the first and second wedge optical plates obtained by the rotation angle measurement means. And an error angle calculation circuit that calculates and outputs an angle.

(2) In the configuration of (1), the rotation drive means includes one drive motor and a gear transmission means for converting rotation of the drive motor into rotation of the first and second wedge-shaped optical plates. And

(3) In the configuration of (1), the pulse detector includes light transmitting means for taking in a part of the laser output of the laser device and irradiating the laser output to a photodetector in the laser receiver. And outputting a laser oscillation pulse detection signal from the laser receiver.

The laser distance measuring apparatus according to the present invention is configured as follows. (4) A laser device that performs a pulse operation at a constant period, a beam expander that narrows the spread angle of a pulse laser beam output from the laser device, and a wedge type rotatably arranged on the optical axis of the output beam of the beam expander. An optical plate, rotation driving means for rotating the wedge-shaped optical plate, and a detector which receives reflected light of the laser beam emitted through the first and second wedge-shaped optical plates and converts the reflected light into an electric signal. A laser receiver that converts and amplifies and outputs, a pulse detection unit that detects a laser oscillation pulse of the laser device, and starts counting up in response to a signal from the pulse detection unit. A counter for measuring the distance from the laser device to the target by stopping the counting.

(5) In the configuration of (4), the pulse detector includes light transmitting means for taking in a part of the laser output of the laser device and irradiating the laser output to a photodetector in the laser receiver. And outputting a laser oscillation pulse detection signal from the laser receiver.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration of a laser tracking apparatus according to the present invention. Reference numeral 31 denotes a laser apparatus that performs a pulse operation at a constant period. The laser beam emitted from the laser device 31 is reduced in beam spread angle by a beam expander 32, and then the first and second wedge optical plates 3
The light is radiated in a predetermined direction after passing through the light emitting elements 3, 36.

Here, the first wedge-shaped optical plate 33 is driven to rotate on the optical axis of the laser beam by a drive motor 34. The rotation angle is detected by the rotation angle measurement device 35 and sent to the error angle calculation circuit 41. Similarly, the second wedge-shaped optical plate 36 is driven to rotate by a drive motor 37. The rotation angle is detected by the rotation angle measurement device 38 and sent to the error angle calculation circuit 41.

When the above-mentioned radiation laser beam is reflected by a target (not shown), a part of the laser beam returns to the laser tracking device. The laser receiver 39 receives the laser reflected light, and the optical lens 3 for condensing the laser reflected light.
91, a photodetector 392 that receives the laser reflected light condensed by the optical lens 391 and converts it into an electric signal, and a preamplifier that amplifies the detection signal output from the photodetector 392 to a certain level. 393 and this preamplifier 393
And a variable amplifier (PGA) 394 for controlling the amplitude of the output signal of the counter 40 in accordance with the count value from the counter 40. The output of the variable amplifier 394 is supplied to the counter 40 and the error angle calculation circuit 41 as the output of the laser receiver 39.

On the other hand, the start pulse detector 42 detects the rise of the laser output of the laser device 31.
The laser detection signal is supplied to a counter 40 and an error angle calculation circuit 41.

The counter 40 includes a start pulse detector 4
The count-up is started by receiving the laser output light detection signal from 2, the count-up is stopped by receiving the laser reflected light detection signal from the variable amplifier 394, and the distance from the laser device 31 to the target is measured from the count value. Is what you do. Further, the error angle calculation circuit 21 outputs the rotation angle measurement devices 35 and 38 when outputting the pulse from the laser receiver 39.
The angle of error with respect to the target is calculated from the rotation angles of the wedge-shaped optical plates 33 and 36 obtained by the above.

That is, the laser tracking device of the present embodiment does not require the beam divergence angle to be larger than the tracking accuracy, so that the laser tracking device per one pulse of the transmission laser light is different from the conventional laser tracking device shown in FIG. Even if the energy is small, distance measurement and angle measurement can be performed at a greater distance.

By rotating the wedge-shaped optical plates 33 and 36 at different rotation speeds, the laser beam can be spatially scanned. FIG. 2 shows an example of this beam space scanning. In FIG. 2, a indicates a locus drawn by the beam center, b1 indicates a beam irradiation range at a certain moment, and b2 indicates a beam irradiation range at another moment.

If a target exists within the beam irradiation range, the reflected light from the target is received by the laser receiver 39. On the other hand, the transmission timing of the laser transmission beam is detected by the start pulse detector 42. Therefore, the time measurement of the counter 40 is started by the start pulse generated by the start pulse detector 42, and the time measurement of the counter 40 is stopped by the received pulse generated by the laser receiver 39. Time intervals can be measured. At this time, since the speed of light is known, target distance information can be obtained from the time interval.

The calculation formula is shown below. r = cN / fcount Here, r is the target distance, c is the speed of light, N is the count number of the counter 40, and fcount is the counter frequency.

The error angle calculation circuit 41 stores the rotation angles from the wedge-shaped optical plates 33 and 36 when the start pulse is generated, and when the corresponding reception pulse is generated, calculates the rotation angle from these rotation angles. The target can be tracked by outputting the irradiated beam irradiation direction as error angle information with respect to the target.

The calculation formula is shown below. ε _AZ = W1 cos (θ1) + W2 cos (θ2) ε _EL = W1 sin (θ1) + W2 sin (θ2) Here, ε _AZ and ε _EL are the error angle in the AZ direction and the error angle in the EL direction, W1, W2. The transmission deflection angles of the wedge-shaped optical plates 33 and 36, and θ1 and θ2 are the rotation angles of the wedge-shaped optical plates 33 and 36.

In this type of laser tracking device, the beam divergence angle can be reduced as compared with the entire tracking field of view. As a result, laser tracking can be performed with a laser device having a smaller energy per pulse than the conventional laser tracking device shown in FIG.

FIG. 3 shows another embodiment of the laser tracking apparatus according to the present invention. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals, and different parts will be described here.

The laser tracking device of the present embodiment comprises a driving means for rotating the first wedge-shaped optical plate 33 and a second wedge-shaped optical plate 3 out of the components of the laser tracking device shown in FIG.
The drive means for rotating the drive motor 6 is replaced by one drive motor 43 and a gear 44 for transmitting the rotation of the drive motor 43 to the wedge-shaped optical plates 33 and 36. In the case of this configuration, the rotation angle measuring devices 35 and 38 are provided in the rotation transmission path of the gear 44, respectively, and the operation thereof is the same as that of the previous embodiment, but the rotation speed of the wedge-shaped optical plates 33 and 36 is changed. Requires the gear 44 to be switched.

FIG. 4 shows still another embodiment of the laser tracking device according to the present invention. In FIG. 4,
The same parts as those in FIG. 1 are denoted by the same reference numerals, and only different parts will be described here.

The laser tracking device of the present embodiment differs from the components of the embodiment shown in FIG. 1 in that the output beam of the laser device 31 is changed to the light detector of the laser receiver 39 by the optical fiber 45 instead of the start pulse detector 42. 392. That is, by setting the pulse width of the laser beam sufficiently short, the laser beam is extinguished before the reflected laser beam returns, so that the photodetector 392 can be used as a start pulse detector. According to this configuration, the number of components of the component can be reduced.

Next, an embodiment of the laser distance measuring apparatus according to the present invention will be described. FIG. 5 shows the configuration.
A pulse laser device 51; a beam expander 52 for reducing the spread angle of the output beam of the pulse laser device 51; a wedge-shaped optical plate 53 that rotates to scan the radiation direction of the laser beam; A drive motor 54 for rotating the plate 53, a condensing optical system 551 and a detector 55
And a start pulse detector 56 for electrically converting the laser oscillation timing.
The count is started by receiving the signal from the start pulse detector 56, and the counting is stopped by the pulse from the laser receiver 55.
It comprises a counter 57 for measuring the distance from 1 to the target.

The laser distance measuring device shown in FIG. 5 can extend the distance measuring distance for a small target as compared with the laser distance measuring device shown in FIG. That is, the beam can be spatially rotated by rotating the wedge-shaped optical plate. FIG. 6 shows this beam space scanning. By rotating and scanning the beam in this manner, the range of possible errors of the target position can be covered.

FIG. 7 has the same laser output power, FIG.
FIG. 5 shows a comparison between the laser beam densities of the conventional laser distance measuring apparatus shown in FIG. 5 and the laser distance measuring apparatus of the present invention shown in FIG. 5, in which the solid line shows the present invention and the dotted line shows the conventional case. . As can be seen from the figure, the laser distance measuring device of the present invention shown in FIG. 5 has a higher laser beam density, so that a larger reflected power can be obtained, and the distance measuring distance can be obtained when a laser receiver having the same performance is used. Can be stretched.

[0039]

As described above, according to the present invention, a laser tracking device which can use a laser device having a high pulse repetition rate, a large average output but a small energy per pulse, and a small remote target And a laser distance measuring device that can extend the distance measurement distance to the laser beam.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a laser tracking device according to the present invention.

FIG. 2 is a pattern waveform diagram showing an example of a state of beam space scanning according to the embodiment.

FIG. 3 is a block diagram showing a configuration of another embodiment of the laser tracking device according to the present invention.

FIG. 4 is a block diagram showing a configuration of another embodiment of the laser tracking device according to the present invention.

FIG. 5 is a block diagram showing a configuration of an embodiment of a laser distance measuring apparatus according to the present invention.

FIG. 6 is a schematic diagram illustrating an example of a state of beam space scanning according to the embodiment.

FIG. 7 is a diagram showing a laser beam density of the laser distance measuring apparatus according to the embodiment in comparison with a conventional laser distance measuring apparatus having the same laser output power.

FIG. 8 is a block diagram showing a configuration of a conventional laser tracking device.

FIG. 9 is a perspective view showing a configuration of a four-element detector used in a conventional laser tracking device.

FIG. 10 is a block diagram showing a configuration of a conventional laser distance measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Laser apparatus 12 ... Beam expander 13 ... Laser receiver 131 ... Optical lens 132 ... 4 element detector 133-136 ... Preamplifier 137-1310 ... Variable gain amplifier (PGA) 14 ... Counter 15 ... Error angle calculation circuit 151 ... Sum calculation circuit 152,153,156,157 ... Adder 154,158 ... Subtractor 155,159 ... Divider 16 ... Start pulse detector 21 ... Pulse laser device 22 ... Beam expander 23 ... Laser receiver 231 ... Condensing optical system 232 Beam detector 24 Counter 31 Laser device 32 Beam expander 33, 36 Wedge-shaped optical plate 34, 37 Drive motor 35, 38 Rotation angle measuring device 39 Laser receiver 391 Optical lens 392 photodetector 393 preamplifier 394 variable amplifier (PGA) 40 cow 41: Error angle calculation circuit 42: Start pulse detector 43: Drive motor 44: Gear 45: Optical fiber 51: Pulse laser device 52: Beam expander 53: Wedge-shaped optical plate 54: Drive motor 55: Laser receiver 56 ... Start pulse detector 57 ... Counter

Claims (5)

[Claims] 1. A laser device that performs a pulse operation at a constant period, a beam expander that narrows a spread angle of a pulse laser beam output from the laser device, and a rotatable output optical axis of the beam expander. First and second wedge-shaped optical plates, rotation driving means for rotating the first and second wedge-shaped optical plates, and a second measuring device for measuring a rotation angle of the first and second wedge-shaped optical plates. First and second rotation angle measuring means; pulse detecting means for detecting a laser oscillation pulse of the laser device; and reflected light of a laser beam transmitted through the first and second wedge-shaped optical plates. A laser receiver that receives light from a detector, converts the signal into an electric signal, amplifies and outputs the signal, and starts counting up in response to a detection signal from the pulse detecting means, and counts with a pulse from the laser receiver. A counter for measuring the distance from the laser device to the target by topping, and a target from the pulse output of the laser receiver and the rotation angles of the first and second wedge-shaped optical plates obtained by the rotation angle measurement means. A laser tracking device comprising: an error angle calculation circuit that calculates and outputs an error angle of the laser beam. 2. The apparatus according to claim 1, wherein said rotation drive means includes one drive motor and gear transmission means for converting rotation of said drive motor into rotation of said first and second wedge-shaped optical plates. The laser tracking device according to claim 1. 3. The pulse detector further comprises a light transmitting means for receiving a part of a laser output of the laser device and irradiating the laser output to a photodetector in the laser receiver. 2. The laser tracking device according to claim 1, which outputs a pulse detection signal. 4. A laser device which performs a pulse operation at a constant period, a beam expander for narrowing a divergence angle of a pulse laser beam output of the laser device, and a rotatable output optical axis of the beam expander. A wedge-shaped optical plate; a rotation driving means for rotating the wedge-shaped optical plate; and a detector for receiving reflected light of a laser beam transmitted through the first and second wedge-shaped optical plates and receiving the reflected light by a detector. A laser receiver that converts the signal into a signal and outputs the amplified signal; a pulse detection unit that detects a laser oscillation pulse of the laser device; a signal from the pulse detection unit that starts counting up; A laser distance measuring device comprising: a counter for measuring a distance from the laser device to a target by stopping counting with a pulse. 5. The pulse detector according to claim 1, further comprising: a light transmitting unit that captures a part of the laser output of the laser device and irradiates the laser output to a photodetector in the laser receiver. 5. The laser distance measuring device according to claim 4, which outputs a pulse detection signal.