JP2840951B2 - Automatic collimation device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic collimation device, and more particularly, to a marine operation for measuring the position of a coastal work pedestal equipped with a lightwave distance meter in a land station and performing high-precision positioning. It is suitable for use in systems.

[Summary of the Invention]

By diverging the collimating servo light to be transmitted to the corner cube prism of the target point, the incident angle of the return light of the collimating servo light reflected by the reflector and the shift of the collimating optical axis, With the angle at which the return light is incident,
This is an automatic collimation device that detects the amount and direction of the displacement of the collimating optical axis and corrects the displacement of the optical axis.

[Conventional technology]

In civil engineering work, harbor work, coastal work, and the like, there is a need for a system that measures the position or distance of a moving object such as a bulldozer, a dredger, a work cradle from a fixed position.

Conventionally, a light wave distance meter is provided at one of a fixed position and a moving body, and a reflector (corner cube prism or the like) is provided at the other, and an automatic collimation type is used in which these optical axes coincide with each other, so that a moving body such as a gantry is shaken. There has been known a system capable of performing position measurement without any trouble even if moved (for example, Japanese Utility Model Publication No. 59-8221).

A known automatic collimating lightwave distance meter has a collimating servo optical axis parallel to the distance meter, and divides collimating servo light from a measurement target point into four light-receiving elements (the light-receiving surface is divided into four horizontal and vertical quadrants). ), And detects the deviation of the incident angle in the up, down, left, and right directions, feeds back the detected output to the horizontal and vertical oscillating motors, and focuses the servo light at the origin of the light receiving element. It has a servo system.

[Problems to be solved by the invention]

An automatic collimating device provided in a conventional automatic collimating type optical wave distance meter receives collimating servo light transmitted from the reflector side and matches the optical axis of the objective lens with the servo optical axis of the partner station. Because of this configuration, it was necessary to provide a light source for collimating servo light at the partner station.

Therefore, it is conceivable to transmit the collimated servo light from its own station, receive the servo light reflected by the reflector and returned, and collimate the optical axis of the objective lens with the reflector. In this case, it is necessary to use a corner cube prism for the reflector in order to reliably return the transmitted servo light to its own station. The corner cube prism reflects reflected light parallel to the incident light to the partner station. On the other hand, the collimating servo light transmitted toward the corner cube prism is converged by the light transmitting lens in parallel with the collimating optical axis. Therefore, even if the collimating optical axis is slightly displaced, the reflected light from the corner cube prism is parallel to the collimating optical axis, and the return light does not include information on the angular displacement of the collimating optical axis. Therefore, even if the return light from the corner cube prism is received by the four-divided light receiving element, the displacement of the collimating optical axis cannot be detected, so that the collimating servo light is transmitted from the own station to perform automatic collimation. The servo system could not be configured.

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

[Means for solving the problem]

The automatic collimating device of the present invention includes a light-emitting element (light-emitting diode 20) arranged at the focal position of the light-sending lens 12, and is adapted to collimate quasi-parallel rays having a small divergence angle radially diverging in the light-sending direction. A light transmitting optical system for transmitting the quasi-servo light 14 to the target point, and a return light of the collimation servo light reflected by the corner cube prism 7 at the target point, and an imaging point of the return light; The optical system includes a light receiving optical system including a position sensor 23 for detecting a deviation from the image forming origin on the light receiving surface, and a mechanism for correcting an optical axis angle based on an output of the position sensor.

[Action]

Since the collimating servo light 14 is diverging, the return light reflected at the collimation position is incident parallel to the collimation optical axis, but the return light reflected at the position deviated from the collimation position has a deviation amount and deviation. The light enters the light receiving system at an incident angle corresponding to the direction. Therefore, the imaging point of the return light from the shifted position is determined by the position sensor.
It is formed at a position shifted from the image forming origin on the light receiving surface of the light receiving surface 23. The angle of the optical axis is corrected in a direction in which the deviation is eliminated, and the incident angle is reduced to zero. Thereby, the return light becomes parallel to the collimating optical axis, and the collimating optical axis collimates the target point.

〔Example〕

FIG. 1 is a block diagram of an automatic collimation type optical distance meter according to an embodiment of the present invention, and FIGS. 2 and 3 are front views of the optical distance meter and a reflector. The land-based lightwave distance meter 3 is disposed in a collimation device 2 provided on the base 1. The reflector 4 including the corner cube prism 7 is arranged on the side of the boat.

The collimating device 2 includes a horizontal arm 8a rotatable in a horizontal plane and a vertical arm 8b rotatable in a vertical plane, and is driven by an X-axis gear motor 9 and a Y-axis gear motor 10, respectively. On the vertical arm 8b, a light transmitting / receiving unit 11 including a light transmitting lens 12 and a light receiving lens 13 having optical axes parallel to each other is mounted.

FIG. 1 shows a collimating servo circuit connected to a collimating optical system 2a (land station) of the automatic collimating device 2. Collimating optics
A light-emitting diode 20 for light transmission is arranged at the focal point of the light-sending lens 12a, and a sine wave output (5 kHz) of an oscillator 21 is supplied through an LED drive circuit 22. Thus, the AM-modulated collimating servo light 14 is transmitted through the light transmission lens 12 to the pedestal side corner cube prism 7.

The collimating servo light 14 is reflected by the corner cube prism 7 and returned in a direction parallel to the incident direction. Therefore, the return light 15 of the collimated servo light 14 transmitted from the land station is returned to the light receiving system of the land station, and is received by the position sensor 23 via the light receiving lens 13.

The position sensor 23 may be, for example, a two-dimensional (XY plane) semiconductor position detecting element that detects the position of the light spot from the origin. This element has a structure in which four electrodes (two pairs of X and Y) are provided on the four sides of a photodiode having a rectangular light receiving surface, and the charge generated at the position where the light spot hits is transmitted as a photocurrent to each electrode. The voltage is divided by the resistance layer on the light receiving surface in inverse proportion to the distance between the electrodes, and the voltage is extracted from each electrode.

In FIG. 1, the output of each electrode of the position sensor 23 is a current-voltage conversion amplifier 24a-d, a band-pass filter 25a-
The signal passes through d, is synchronously detected by the detectors 26a to 26d, and is converted into a DC level signal having a level value corresponding to the light receiving position. The detection outputs of the four poles are converted into digital values by an A / D converter 27 as upper and lower (U, D) and left and right (L, R) position detection signals, and then input to a microprocessor in a system controller 28. Be included.

In the microprocessor, the XY coordinate position of the light receiving spot on the light receiving surface of the position sensor 23 is calculated from the U, D, L, and R position detection data. The system controller 28 derives drive pulses to the motor drive circuits 30X and 30Y for each axis based on the coordinate position data,
The shaft and Y-axis gear motors 9 and 10 are driven, respectively. The servo loop from the position sensor 23 to the motors 9 and 10 is a sensor
The operation is performed so that the 23 light receiving spots are located at the origin of the XY coordinates of the light receiving surface. In the state where the servo is working, the optical axis of the lightwave distance meter 3 of the land station is correctly directed to the reflector 4 of the shore station, and the distance can be measured.

Means for finely adjusting the direction of the optical axis of the collimating device 2 is provided. In Figure 1, this fine adjustment means is a joystick
Although it is 31, a fine adjustment knob may be provided in the gear system of the motors 9 and 10 of each XY axis. A voltage output corresponding to the operation of the joystick 31 in the X and Y directions is sent to the system controller 28 via the A / D converter 32,
The fine adjustment drive pulse is derived from 28 to the motor drive circuits 30X and 30Y, and the motors 9 and 10 are finely moved. Accordingly, the operator operates the joystick 31 while looking into the collimating telescope 49 of the optical distance meter 3 to collimate the target 50 of the reflector 4 on the side of the boat. When the start button of the servo is pressed at the time when the collimation is completed, the above-mentioned collimation servo starts, and thereafter, the automatic collimation following the shake or movement of the gantry is performed.

The deviation of the optical axis and the like detected by the position sensor 23 are displayed by the display devices 33A to 33C connected to the system controller 28. The hands of the indicators 33A and 33B indicate deviations from the origins of the X axis (horizontal direction) and the Y axis (vertical direction). The pointer of the display 33C indicates the total light receiving level (light receiving intensity) of the position sensor 23.

When the circuit section 34 of the optical distance meter 3 is operated in the collimated state, the transmission / reception unit 35 located at the focal position of the objective lens 5 transmits the distance measuring light of about 15 MHz (AM) and reflects the light from the measuring point. Is received. The phase difference between the transmitted light and the received light is measured by the circuit unit 34, and the inter-station distance is calculated based on the measured phase difference. The distance data is transferred to the system controller 28 through the interface 36.

In order to perform the automatic collimation as described above, in the embodiment, as shown in the collimation servo light explanatory diagram of FIG. By increasing the area, collimated servo light
14 are diverging.

In FIG. 4, assuming that the focal length of the light-sending lens 12 is F ₁ and the width of the light-emitting surface of the light-sending light-emitting diode is a, the focal position of the light-sending lens 12 is as shown in FIG. The divergence angle α of the light emitted from the light emitting diode 20 placed at Becomes Therefore, for example, if F = 80 mm and a = 0.4 mm, the divergence angle α is about 17 minutes and 11 seconds.

Collimated servo light with a transmitting optical system with a divergence angle of 17 minutes 11 seconds
When 14 is transmitted, the diameter D of the light beam expands to about 5 m at a position 1 km away. Therefore, as shown in the irradiation area explanatory diagram of FIG. 6, the collimated servo light when collimating the point A is used.
14 irradiates a circle having a diameter D = 5 m around the point A.
If the divergence angle spreads for 1 second, the light beam will spread 5 mm at 1 km, and if it spreads for 10 seconds, it will spread 10 mm at 200 m.

Since the collimating servo light 14 is irradiated over a wide range,
Even if the stage being collimated at the point A moves horizontally to the points B and C as shown by arrows R and L, the collimated servo light is applied to the corner cube prism 7 disposed on the stage.
14 enters. Therefore, when the gantry moves to the point B, return light from the point B is obtained, and when the gantry moves to the point C, the light returns to the point C.
Return light from the point is obtained.

As described above, the return light 15 from the corner cube prism 7 is received by the light receiving system, and a light receiving spot is formed on the position sensor 23. In the case of the embodiment, since the collimating servo light 14 is diverged, the light receiving spot on the position sensor 23 is formed corresponding to the position of the gantry.

That is, since the collimating servo light 14 is divergent light, the collimating servo light 14 incident on the corner cube prism 7 at a position shifted from the collimating position is not parallel to the collimating optical axis 14n. For example, a case where there are corner cube prisms 7A, 7B, and 7C at points A, B, and C in FIG. 6 will be described.

First, the center light of the light beam of the collimating servo light 14 is set to 14A,
An optical axis parallel to the center light 14A is defined as a collimating optical axis 14n. When the point A is collimated as described above, the center light 14A is applied to the corner cube prism 7A at the point A as shown in FIG.
Is incident. Therefore, the return light 15A from the corner cube prism 7A is parallel to the center light 14A, that is, parallel to the collimating optical axis 14n. Therefore, the light receiving spot by the return light 15A is formed at the origin of the XY coordinates on the light receiving surface of the position sensor 23.

Next, a light receiving spot due to the return light reflected by the corner tube prism 7B at the point B will be described. Since point B is displaced to the right in the direction from the reference position point A visual, it is inclined to the right by an angle theta _R junior servo beam 14B is collimated optical axis 14n vision entering the corner cube prism 7B. In this case, the return light 15B from the corner cube prism 7B
Since parallel and collimated servo beam 14B is inclined by an angle theta _R junior optical axis 14n visual. Therefore, return light from point B
15B, as shown in the explanatory view of the light receiving optical system of FIG. 7, incident angle theta _R from the right direction with respect to the quasi-optical axis 14n viewed in the light receiving lens 13. Therefore, the light spot formed by the return light 15B is not formed at the focal point f of the light receiving lens 13, that is, at the origin of the XY coordinates on the light receiving surface of the position sensor 23, and the incident angle θ _R
Are formed shifted in the X direction by a distance corresponding to. Therefore, if the amount of deviation from the origin is detected and the optical axis is controlled so that it becomes zero, the collimating optical axis can be directed to point B. That is, when the gantry that has been collimated at point A moves to point B, it can be tracked automatically.

The collimating servo light 14C incident on the corner cube prism 7C at the point C is inclined leftward by an angle θ _L opposite to the collimating servo light 14B incident on the point B. Therefore, the return light 15C from the corner cube prism 7C has the angle θ _L
Only from the left side. Therefore, the light spot due to the return light. 15C with shifts from the origin of only X-Y coordinate distance corresponding to the angle theta _L, the shift direction is deviated direction opposite to the light spot due to the return light 15B from the point B . Therefore, by detecting the direction and amount of deviation from the origin on the light receiving surface of the position sensor 23, even if the gantry moves in any of the up, down, left, and right directions,
The moving direction and the moving distance (angle) can be detected, and the return light 15 from the corner cube prism 7 is received to enable automatic collimation.

In addition, the collimating servo light 14 is transmitted to the corner cube prism 7.
The divergence angle does not spread due to reflection. Therefore, a measurement error due to reflection, a light quantity shortage due to an excessively wide divergence angle, and the like do not occur. Further, in the state where the collimation is maintained, the light spot on the position sensor 23 does not deviate from the origin even if the optical axis of the corner cube prism 7 is tilted due to the shaking of the slide.

Then, the incident angle theta _R and the light receiving lens F ₂ of the returned light will be specifically described relationship between the moving distance r of the light spot. If the focal length of the light receiving lens 13 is F _2, the moving distance R of the light _{spot, tanθ R = r / F 2} ...... since (2), and _{r = F 2 · tanθ R ......} (3). (3) than the movement distance r it can be seen that increases in proportion to the tangent of the incident angle theta _R. Also, the moving distance r
Is proportional to the focal length F _2, by using the long-receiving lens focal length F _2, it is possible to increase the moving distance r with respect to the change of the incident angle, can improve the detection sensitivity.

By the way, the maximum value of the moving distance r is limited by the width W of the light receiving surface of the position sensor 23. For example, when the light receiving width W of the position sensor 23 is 5 mm in both the vertical direction and the horizontal direction (X direction and Y direction), the moving distance r is limited to r <5 mm.
Thus, when the maximum value of the moving distance r is limited, when improving the detection sensitivity by increasing the focal length F _2,
The allowable angle of incidence of the light receiving optical system is reduced, and the detectable range is reduced. For example, the permissible incidence angles α ₁ , α ₂ , α ₃ in each of the light receiving optical systems having a focal length F ₂ of 50 mm, 80 mm, and 130 mm are: Becomes Also, in each light receiving optical system, if the distance that the light spot moves when the incident angle changes for 10 seconds is the detection sensitivity β ₁ , β ₂ , β ₃ , approximately, β ₁ = 5 ÷ 20558/10 = 2.43 μm β ₂ = 5 ÷ 12840/10 = 3.89 μm β ₃ = 5 ÷ 7929/10 = 6.3 μm. Therefore, the long light receiving lens focal length F ₂ is
It is understood that the detection sensitivity is improved although the allowable angle of incidence is reduced.

As shown in FIG. 2, rotary encoders 39 and 40 are provided on the X axis and the Y axis, respectively, and can be used as transits (theodolites). For example, the eighth
It is assumed that the gantry 41 shown by the solid line in the figure has moved to the position shown by the dotted line after a certain time has elapsed. In this case, since the gantry 41 is automatically collimated, the angle θ ₁ after the movement can be automatically measured with the position indicated by the solid line as the origin, and the measured angle θ ₁
, The angular position after the movement can be immediately detected.

Since this distance measuring system can measure both the distance and the angle, if the absolute position before the movement is known, the absolute position can be calculated by reading both the angle and the distance data after the movement. Can be detected.

Also by a rotary encoder 40 provided on the Y axis, it is possible to detect the inclination angle theta ₂ with respect to the horizontal plane as shown in FIG. 9, it is possible to convert the slope distance to horizontal distance.

Thus, the automatic collimating device 2 and the rotary encoder 3
Combining with 9 and 40 makes it possible to configure a transit for a moving object because it can automatically track the moving object and automatically measure the angle from the origin. Further, since the distance and the angle from the origin can be detected, the trajectory of the moving object can be obtained in real time.

One corner cube prism 7 can reflect light entering from a range of about 30 ° toward the light source. However, the moving object may move continuously over a range of 30 °, or may make a full 360 ° rotation. In such a case, the corner cube prism 7 is
The work of directing the direction of the reflector 4 to the measuring station side is required only by providing the reflectors. Figure 10 shows the corner cube prism 7
In this example, the support 42 to which is mounted is formed in a cylindrical shape, and the corner cube prism 7 is provided over the entire peripheral surface. In such a case, 12 corner cube prisms 7 may be provided at intervals of 30 °, but it is preferable to provide about 18 corner cube prisms at intervals of 20 ° in consideration of the safety factor.

As shown in the arrangement diagram of the light transmitting and receiving lens in FIG. 11,
A plurality of light transmitting lenses 12a to 12d around a large light receiving lens 13.
And collimate servo light 14 from each light-sending lens.
May be transmitted. In this case, the frequency of each collimating servo light is set to be the same.

In addition, when a pair of light transmitting lenses 12, 5a and light receiving lenses 13, 5b are used in the collimating servo system and the distance measuring system, respectively,
Attach each pair at an angle of 45 ° as shown in the objective lens layout diagram in Figure 12. With this arrangement, when the corner cube prism 7 moves in the vertical and horizontal directions, there is little danger that collimated servo light cannot enter the corner cube prism 7.

As shown in the block diagram of the automatic collimating lightwave distance meter in FIG. 13, the light transmitting and receiving light path of the collimating device 2 and the light transmitting and receiving light path of the light wave distance meter 3 may be used together. This device uses a light-sending lens
Distance measuring light output from a light emitting diode 45 for a distance meter by a beam splitter 44 inserted between the light emitting diode 12 and the position detecting light emitting diode 20 at an angle of about 45 ° with respect to the optical axis.
46a is put on the same light transmission optical path as the collimating servo light 14, and is sent to the corner cube prism 7 on the side of the boat.

The return light 46b of the distance measurement light that has returned on the same light receiving optical path as the return light 15 of the collimating servo system is transmitted to the distance meter by the beam splitter 47 inserted between the light receiving lens 13 and the position sensor 23. The light receiving diode 48 is branched. And
The light receiving output of the light receiving diode 48 is sent to the lightwave distance meter circuit section 34, and the above-described distance detection is performed. In the embodiment, as the beam splitters 44 and 47, those having a reflection surface formed in a cubic block glass are used.
Distortion does not occur when combining and splitting each light.

In the case where one optical path is shared in this way, if the wavelength is separated between the ranging light and the servo light, and the transmission and reflection of each light is performed by using the spectral characteristics of the cut filter, the light can be reduced. The efficiency of shaft disassembly and synthesis is increased.

In this example, a panel-shaped display 37 is used to display the displacement of the optical axis and the amount of received light. This indicator 37
Indicates a bright spot in the Y-axis direction and the X-axis direction in the vertical and horizontal directions of the optical axis, and the total light receiving level is displayed on a bar graph 37a using LEDs.

〔The invention's effect〕

As described above, the present invention relates to the collimation servo of a quasi-parallel ray having a small divergence angle radially diverging from the light emitting element (light emitting diode 20) disposed at the focal position of the light transmitting lens 12 in the light transmitting direction. The light 14 is transmitted to the target point, the return light of the collimated servo light reflected by the corner cube prism 7 at the target point is received, and the image forming point of the return light and the image forming origin on the light receiving surface are determined. By detecting the displacement by the position sensor 23 and correcting the optical axis angle based on the output of the position sensor, the collimating servo light of the quasi-parallel ray reaching the far end with sufficient intensity is projected. Therefore, it is possible to detect the optical axis shift with high sensitivity and to automatically correct the optical axis shift with respect to an extremely distant target on which the corner cube prism is installed.

[Brief description of the drawings]

FIG. 1 is a block diagram of an automatic collimating lightwave distance meter showing one embodiment of the present invention, FIGS. 2 and 3 are front views of a lightwave distance meter and a reflector, and FIG. FIG. 5 is a diagram illustrating a divergence angle, FIG. 6 is a diagram illustrating an irradiation area of collimating servo light, and FIG. 7 is an image formed by return light. 8 is a diagram illustrating an example of angle measurement in a horizontal plane, FIG. 9 is a diagram illustrating an example of tilt angle measurement with respect to a horizontal plane, and FIG. 10 is a modified example of a reflector. FIG. 11 is a front view, FIG. 11 and FIG. 12 are arrangement diagrams showing examples of the arrangement of the objective lens, and FIG. 13 is a block diagram of an automatic collimation type optical distance meter showing an embodiment different from FIG. In the reference numerals used in the drawings, 2 ... collimating device 3 ... light wave distance meter 4 ... reflector 7 ... corner cube prism 8a ... horizontal arm 8b ... vertical arm 9 ... X-axis gear motor 10 … Y-axis gear motor 12… Light transmitting lens 13… Light receiving lens 14… Collimating servo light 15… Return light 20… Light emitting diode 23… Position sensor.

Claims (1)

(57) [Claims] 1. A light-emitting element disposed at a focal position of a light-sending lens, and transmits collimating servo light of a quasi-parallel ray having a small divergence angle radially diverging in a light-sending direction to a target point. Receiving the return light of the collimating servo light reflected by the light transmitting optical system and the corner cube prism at the target point, and detecting a shift between the image forming point of the return light and the image forming origin on the light receiving surface. An automatic collimating device, comprising: a light receiving optical system having a position sensor for performing the operation; and a mechanism for correcting an optical axis angle based on an output of the position sensor.