JPS63225121A - Autocollimation type light wave range finder - Google Patents

Abstract

PURPOSE:To enable automatic collimation to be performed by providing a mechanism for alternately oscillating the optical axis of an objective lens in horizontal and vertical directions and detecting the deviation of servo light reflected from a reflector on the optical axial. CONSTITUTION:A range finder is constituted by a light emitting element 16 for emitting collimation servo light 18 to a reflector 4 at a ranging target point, a photosensitive element 19 for receiving reflected light from the reflector 4, a servo mechanism (servo circuit 2a, X axis gear motor 11, Y axis gear motor 12) for alternately oscillating the optical axes of objective lenses (light feed lens 13, light receiving lens 14) in horizontal and vertical directions and a light wave range finder 3 directed in the collimating direction of the objective lenses. The deviations of the optical axes are detected by change in a received light level and collimation servos 11 and 12 are alternately conducted in horizontal and vertical directions so that the deviations become maximum. Then, the quantity of the fed servo light 18 is adjusted and the received light level is set to a prescribed value. When the received light level is stored, a range is measured 3. Thereafter, the collimation and range measurement are alternately performed in the same manner.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic collimation type light wave distance meter, and in particular, to a land station equipped with a light wave range meter to measure the position of a coastal work platform and to perform highly accurate positioning. This is suitable for use in offshore work systems.

[Summary of the invention]

The collimation servo light is projected toward the reflector, and the optical axis is alternately swung horizontally and vertically based on the received light output so that the level of the reflected light is maximized. This is an automatic collimation type light wave distance meter that operates at

[Conventional technology]

In civil engineering work, port construction work, coastal construction work, etc., there is a need for a system that measures the position or distance of a movable object such as a bulldozer-1 dredger or a work slip from a fixed position.

Conventionally, a light wave distance meter was installed on one side of a fixed position and a moving object, and a reflector (corner cube prism, etc.) was installed on the other, and an automatic collimation system was used to align these optical axes with each other. A system is known that allows position measurement without any problem even when moving (for example, Utility Model Publication No. 59-822
Publication No. 1).

A known automatic collimation type light wave rangefinder has a collimation servo optical axis parallel to the rangefinder, and transmits the collimation servo light from the measurement target point into four directions.
The servo light is received by a divided light-receiving element (a photodiode, etc. whose light-receiving surface is divided into four horizontal and vertical quadrants), and the output is fed back to the horizontal and vertical swing motors to form a servo light at the origin of the light-receiving element. It is equipped with a servo system.

[Problem that the invention seeks to solve]

Conventional automatic collimation type optical distance meters are configured to receive collimating servo light emitted from the reflector side and align the optical axis of the objective lens with the servo optical axis of the other station, so the other station cannot see it. It was necessary to provide a quasi-servo light source.

Therefore, it is conceivable to transmit collimated servo light from the local station, receive the servo light reflected by a reflector, and collimate the optical axis of the objective lens to the reflector. However, when using a corner cube prism as a reflector,
Even if the collimated optical axis is slightly deviated, the emitted light will return in parallel, so a four-segment photodiode cannot detect the deviation of the optical axis, so a servo system cannot be constructed.

SUMMARY OF THE INVENTION An object of the present invention is to enable automatic collimation by detecting a shift in the optical axis using servo light reflected by a reflector and returned.

[Means for solving problems]

The automatic collimation type optical distance meter of the present invention includes: a light emitting element 16 that transmits a collimating servo light 18 to a reflector 4 at a measurement target point; a light receiving element 19 that receives reflected light from the reflector;
A servo mechanism (servo circuit 2
a, X-axis and Y-axis gear motors 11, 12), and a light wave distance meter 3 oriented in the collimation direction of the objective lens.

[Effect]

Taking advantage of the fact that the deviation of the optical axis appears as a change in the level of received light, the optical axis is collimated to the reflector of the measurement target based on the reflected light of the servo light from the range finder. Since horizontal and vertical collimation operations are performed alternately, horizontal and vertical servo detection units can be used with - number of photodetectors, without using four-quadrant photodetectors to detect vertical and horizontal deviations of the optical axis. can be configured. Since horizontal and vertical collimation cannot be performed at the same time, there will be a delay in response to changes in the optical axis, but if distance measurement is performed immediately after collimation is achieved, the response delay will not be a problem.

〔Example〕

FIG. 1 is an overall block diagram of an automatic sighting and ranging system for a marine work platform showing an embodiment of the present invention, and FIGS. 2 and 3 are front views of a light wave distance meter and a reflector. The light wave distance meter on the land side is arranged in a collimation device 2 provided on a base 1. A reflector 4 including a corner cube prism is arranged on the ship's platform side.

The collimation device 2 includes a horizontal arm 8 that is rotatable in a horizontal plane and a vertical arm 9 that is rotatable in a vertical plane, and is driven by an X-axis gear motor 11 and a Y-axis gear motor 12, respectively.

A light transmitting lens 13 and a light receiving lens 14 are mounted on the vertical beam arm 9.
A light transmitting/receiving unit 15 is attached. A light emitting element 16 such as an LED is arranged at the focal point of the light transmitting lens 13, and a light receiving element 19 such as a photodiode is arranged at the focal point of the light receiving lens 14.

At the time of measurement, the collimating telescope 41 installed on the measuring station side
While looking at the target 42 provided on the reflector, the vertical fine adjustment knob 43 and the horizontal fine adjustment knob 44 are adjusted to collimate the optical axes of the objective lenses 13 and 14 onto the corner cube prism 7.

After collimating the optical axes of the objective lenses 13 and 14 onto the corner cube prism 7 as described above, when a power switch (not shown) is turned on, the collimating device 2 and the optical range finder 3 become operational.

A 5 KHz AM-modulated sine wave servo signal is supplied from an oscillation modulation circuit 17 to the light emitting element 16 of the collimation servo circuit 2a. As a result, the collimated servo light 18 is projected from the light emitting element 16 through the light transmitting lens 13 toward the boat platform.

Although the servo light 18 is a substantially parallel light beam, it is somewhat distorted due to the area of the light emitting element, etc., and the amount of light is large at the center and attenuates toward the periphery.

The servo light 18 reflected by the corner cube prism 7 of the reflector 4 and returned passes through the light receiving lens 14 and converges at its focal point, and is received by the light receiving element 19. The received light output is amplified to a specified voltage level by a preamplifier 21 and a filter amplifier 22.

The amplified light-receiving voltage is introduced into the input terminal of the comparator 23 and compared with the reference voltage E introduced into the comparison terminal of the comparator 23. As a result of the comparison, if the received light voltage level is lower than the reference voltage E, the degree of modulation of the oscillation modulation circuit 17 is increased, the intensity of the collimated servo light 18 transmitted from the light emitting element 16 is increased, and the received light voltage level is increased. Increase to the specified value.

On the other hand, when the received light voltage level is higher than the reference voltage, the modulation degree is decreased.

Note that if the modulation degree must be significantly adjusted to match the received light voltage level to the specified level, the AGC
A circuit may be provided to automatically control the gains of the preamplifier 21 and filter amplifier 22 using the output of the comparator 23, for example. The light reception voltage level adjusted to a constant level in this way is held in the peak hold circuit 25 (this holding voltage is set to, for example, 4 [V]).

With the above steps, the preliminary setting of the collimation servo system is completed. In this state, the modulation degree in the oscillation modulation circuit 17 is fixed. In addition, as mentioned above, the preamplifier 21 or the filter amplifier 2
When an AGC circuit is provided in 2, its gain is also fixed. Note that this preliminary setting is performed by turning on the manual switch 45.

Next, when the manual switch 45 is turned off, automatic aiming mode is entered. In this mode, the light receiving voltage amplified by the preamplifier 21 and filter amplifier 22 is supplied to the comparator 26. The output of the peak hold circuit 25 is supplied to the other input terminal of the comparator 26. When the received light voltage level drops beyond a predetermined tolerance range (0.IV if healthy) with respect to the voltage held in the peak hold circuit 25, the output of the comparator 26 is monitored. Control CPU27
detects this drop in the light reception voltage level, resets the peak hold circuit 25, and holds the light reception voltage at that time in the peak hold circuit 25. At this time, the optical axis of the servo optical system is shifted from the leveling point C as shown at point a in FIG. 4, and the hold voltage of the peak hold circuit 25 has decreased to about 3V.

Next, the CPU 27 sends a drive start signal to the motor drive circuit 28 to rotate the X-axis gear motor 11. X
When the optical axis is moved by the shaft gear motor 11 from the position shown at point a to the direction shown at point b in FIG.
The CPU 27 discriminates this based on the output, and sends a reversal signal to the motor drive circuit 28 to rotate the X-axis gear motor 11 counterclockwise. As a result, the optical axis rotates counterclockwise from point b in FIG. 4, and as a result, the received light voltage level rises as shown in FIG.

When the rotation reaches point C in FIG. 4, the received light voltage level is 31.
returns to the peak voltage P (V), and further decreases after passing the 0 point. When the received light voltage begins to decrease from the peak voltage, the CPU 27 determines this based on the output of the comparator 26, and the voltage shown in FIG. The X-axis gear motor 11 is reversed clockwise from point d. Then, the motor 11 is stopped when the received light voltage level reaches approximately the peak value 4■ of the peak hold circuit 25. This achieves horizontal collimation.

Next, a signal is sent to the motor drive circuit 29 to drive and control the Y-axis gear motor 12 in the same manner as described above, and the optical axis is set at the position of the maximum reception level in the vertical direction.

For more accurate collimation, do the following.

That is, when the received voltage level drops, the peak hold circuit 25 is reset, and the received light voltage at that time is held in the peak hold circuit 25 as Vo as shown in FIG. Then, the X-axis gear motor 11 is rotated in a direction in which the received light voltage level increases, that is, in the example shown in FIG. 5, counterclockwise from the position e. The received light voltage level increases as the X-axis gear motor 11 rotates counterclockwise, reaches a maximum at the position C in FIG. 5, and further coincides with the hold voltage Vo at the position g. During this time, from position e to position g
If you count the number of pulses required to rotate the X-axis gear motor 11 until the end of the rotation, and reverse the X-axis gear motor 11 clockwise with 1/2 of the total number of pulses, the objective lens 13.14 The optical axis of the reflector 4 can be accurately collimated.

After collimating the optical axes of the transmitting/receiving lenses 13 and 14 onto the reflector 4 as described above, the CPU 27 applies the operation signal si to the optical distance meter 3 to perform distance measurement. At the same time, the gate of the comparator 23 is opened to readjust the intensity of the transmitted light so that the received light voltage level matches the reference voltage E.

Although the optical distance meter 3 shares an optical axis with the light sending lens 13 and the light receiving lens 14 of the servo system in this embodiment, the servo optical system and the distance measuring optical system may be provided separately.

A semi-transparent mirror 51 is inserted into the optical axis of the light transmitting lens 13 at an angle of 45''.The distance measuring light is transmitted from the output (1
5MHzFM), the light is reflected by a semi-transparent mirror 51 from a distance measuring light emitting element 5 such as an LED, and is projected onto the reflector 4 side through a light transmitting lens 13.

The reflected light from the corner cube prism 7 of the reflector 4 passes through the light receiving lens 14 and is reflected by a semi-transparent mirror 52 inserted at an angle of 45 degrees to the front axis of the light receiving lens 14, and is focused on a distance measuring light receiving element 6 such as a photodiode. be illuminated. The distance meter circuit 33 calculates the distance by detecting the phase difference between the transmission signal given to the light emitting element 5 and the received signal from the light receiving element 6.

Note that when measuring distance, the distance measurement operation signal S1 is applied from the position control CPU 27 to the AND gate 35, this gate 35 is opened, the motor 48 is driven by the control signal S2 from the distance meter circuit 33, and the light receiving element 6 is The optical aperture 38 is rotated so that the received light level becomes the specified value. When the manual switch 45 is turned on to set the manual distance measurement mode, the AND gate 34 is opened by the high-level mode signal S3, and the optical diaphragm 38 is driven.
AND gate 35 is closed by the low level output of inverter 36.

The shutter 47 in front of the light receiving element 6 is connected to the motor 46
The distance measuring optical path is switched to the calibration optical path prior to measurement. The calibration optical path is provided to calibrate the electrical constants and mechanical constants of the optical distance meter 3 according to conditions such as temperature at the time of measurement, and during calibration, the output light of the light emitting element 5 passes through the optical fiber 39 The light is directly incident on the light receiving element 6. In this state, the measured value is calibrated so that the distance display indicates the zero point.

The above collimation and ranging operations are shown in the flowchart of FIG. First, in steps S1 and S2, a shift in the optical axis is detected based on a change in the received light level, and in steps 83 to S5, collimation servo is performed alternately horizontally and vertically so that the received light level is maximized. Next, in steps S6 and S7, the amount of transmitted servo light is adjusted to match the received light level to a specified value, and the level is stored. Here, distance measurement (step S8) is performed, and thereafter collimation and distance measurement are performed alternately in the same manner.

When the collimation servo system and the distance measurement system share one optical axis, the wavelength of the light emitting element 5 for distance measurement is set to 810 nm, for example, in order to reduce the insertion loss of the semi-transparent mirrors 51 and 52, and the servo It is preferable to make the wavelengths of the light-emitting elements 16 different such as 1l100n, and to use dichroic mirrors or cant filters as the semi-transparent mirrors 51 and 52. A dichroic mirror efficiently passes light with a wavelength of 850 nm or more and efficiently reflects light with a wavelength of 850 nm or more.

In the above example, the light transmitting lens 13 and the light receiving lens 14 are provided separately, but it is also possible to transmit and receive light using one objective lens. For example, the central portion of the objective lens is used for transmitting light, and the outer peripheral portion is used for receiving light.

Alternatively, the upper part of the objective lens may be used for transmitting light, and the lower part may be used for receiving light.

Further, as shown in the modification shown in FIG. 7, the light emitting element 16 and the light receiving element 19 may be shared by the servo system and the distance meter, respectively. In this case as well, the servo period and the distance measurement period are separated, and during servo, the changeover switches 61 and 62 are set to the dotted line side to drive the light emitting element 16 with the output of the oscillation modulation circuit 17, and the light receiving element 1
9 is supplied to the servo circuit 2a. After collimation is achieved, the changeover switches 61 and 62 are switched to connect the light emitting and light receiving elements 16 and 19 to the distance meter circuit 33.

〔Effect of the invention〕

As described above, the present invention detects the deviation of the optical axis based on the level of the reflected light of the servo light projected from the measurement reference point, so there is no need to place a servo light source on the reflector side, and the barrel structure of the ranging system is eliminated. is simplified. Since the collimation optical axis is alternately swung horizontally and vertically for collimation, even with a single light receiving element, it is possible to detect and correct deviations of the optical axes in the four quadrants (up, down, left and right). Therefore, it becomes possible to use a corner cube prism for the reflector. In this case, the projected light and the reflected light become parallel, making it difficult to detect the deviation of the optical axis using a four-quadrant imaging position detection element such as a four-segment photodiode. By doing so, it becomes possible to detect the deviation of the optical axis.

[Brief explanation of drawings]

Fig. 1 is an overall block diagram of an automatic sighting and ranging system showing an embodiment of the present invention, Figs. 2 and 3 are front views of a light wave distance meter and a reflector, and Figs. 4 and 5 are optical FIG. 6 is a graph showing the relationship between axis deviation and light reception level, FIG. 6 is a flowchart showing the operating procedure of the collimation servo, and FIG. 7 is a route map showing a modification of the optical system. In addition, in the numbers used in the drawings, 2.---------------Collimation device 2 a --
---...-Servo circuit 3---------1---Light wave distance meter 4...-
・−−−−−−1−−Reflector 5−・−・−・・〜・・・
・・Light emitting element 6・・・−・・・・Light receiving element 7−・−・−・−・・・・Corner cube prism 8−・・・・Horizontal arm 9-...
--- Vertical arm 11 --- X-axis gear motor 12
-・-----1--・X-axis gear motor 13...
・・・・・−・・Light transmitting lens 14・−・−・・−・−・
-Light-receiving lens 15-・--・--・Light-transmitting/receiving unit 16--・--・Light-emitting element 17--・--・-- Oscillation modulation circuit 18-
...−・−・−・Collimation servo light 19−・−1−−−
−・−・−・It is a light receiving element.

Claims (1)

[Claims] A light emitting element that transmits collimated servo light to a reflector at the measurement target point, a light receiving element that receives the reflected light from the reflector, and an optical axis of the objective lens so that the output level of the light receiving element is maximized. An automatic collimation type light wave range finder comprising: a servo mechanism that swings the light wave alternately in horizontal and vertical directions; and a light wave range finder oriented in the collimation direction of the objective lens.