JP2012112919A - Laser tracker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser tracker configured to suppress the generation of crosstalk and apply a stable servo in a case of actuating a driving source for allowing a target to track a laser beam, when the target is moved.SOLUTION: This laser tracker includes: a laser light source; angle adjusting means which can adjust the angle of the laser beam around two orthogonal axes; a light receiving unit 7 that recognizes position information of reflected light; and measuring means that measures a distance to the target. This laser tracker further includes: control means 5 that controls the angle adjusted by the angle adjusting means on the basis of a gain set in a programmable gain amplifier 17; and gain ordering means 16 that calculates a crosstalk amount of the two angle components of the laser beam in the light receiving unit 7, finds a gain that offsets the crosstalk amount, and sets the gain to the programmable gain amplifier 17.

Description

  The present invention relates to a laser tracker and, for example, relates to a technique for measuring spatial coordinates of an object such as a material, a product, a building, or a natural object in a production field or a measurement field.

Conventionally, a laser tracking technique in which the direction of a laser beam serving as a guide is controlled by a biaxial motor to follow a moving target is known (Patent Document 1). In this case, the spatial direction of the moving target can be known using a biaxial encoder attached to the motor.
The target is generally a retro-reflector or a reflector using three mirrors each called an orthogonal reflector. In any case, the reflector can return light in the incident direction.

  In addition, laser distance measurement technology has been established. For example, laser interferometers such as Agilent (formerly Hewlett-Packard), Renishaw, etc., measure distances of several meters with a resolution of nanometers. (Patent Document 2).

  A device that combines these two technologies, called a laser tracker, can measure the distance and spatial angle from the device to the target and determine the spatial position of the target relative to the device. It is. They are commercialized by API (Automated Precision Inc.), FARO, etc., and the principle is disclosed (Patent Document 3).

JP 62-165114 A JP-A-5-264215 Japanese translation of PCT publication No. 2003-506691

  In the laser tracker shown in FIG. 1, the coordinates (X, Y, Z) of the target can be determined from three numerical values of the distance L measured with the laser beam and its spatial angle (θ, ψ). In the case of this measurement, it is necessary to move the target from a certain reference point to a non-measurement object, and continuously follow the angles (θ, ψ) according to the direction of the target.

When the target moves in the horizontal direction, the θ-axis motor 9 must be rotated to cause the laser beam to follow the target. As the θ-axis motor 9 rotates, the laser light source 2, the length measuring device 4, the light receiving unit 7, and the half mirror 8 (hereinafter referred to as “light receiving unit etc.”) must be rotated simultaneously with the θ-axis motor 9. Don't be. When the light-receiving unit or the like is not rotated, the change information of the position of the laser beam at the light-receiving unit 7 that must be separated in the θ and ψ directions cannot be separated as the θ-axis motor 9 rotates. As a result, when the angle θ is increased, there is an adverse effect such as oscillation of the servo system.
Therefore, in a general laser tracker, a mechanism for rotating the light receiving portion and the like simultaneously with the θ-axis motor 9 is required, but there is a problem that the rotating portion becomes complicated and cable processing becomes difficult.

  When the angle θ is 0 and the target moves in the Y axis direction, the locus of the laser beam on the light receiving unit 7 moves in parallel to the Y axis direction on the light receiving unit 7 as shown in FIG. Therefore, when the movement amount of the locus of the laser beam on the light receiving unit 7 is (x, y) and the conversion rate to voltage is e, the output (X, Y) of the light receiving unit 7 is

となる。

It becomes.

Next, the locus of the laser beam on the light receiving unit 7 when the angle θ is not necessarily 0 and the light receiving unit or the like does not rotate in synchronization with the rotation angle θ of the θ axis motor 9 will be described with reference to FIG. .
First, when the θ-axis motor 9 rotates by an angle θ, the locus of the laser beam in the x and y directions on the light receiving unit 7 rotates by θ. Then, the trajectory of the laser beam in the x direction is decomposed into xcosθ and −xsinθ, and the trajectory of the laser beam in the y direction is decomposed into ycosθ and ysinθ, respectively.
Therefore, if the movement amount of the locus of the laser beam on the light receiving unit 7 is (x, y) and the conversion rate to voltage is e, the output (X, Y) of the light receiving unit 7 is

となる。
この場合、sinθ分だけ、ｘからＹに、また、ｙからＸにクロストークが発生し、θが大きくなると、制御が不安定になるなどの問題が発生する。

It becomes.
In this case, crosstalk occurs from x to Y and from y to X by the amount of sin θ, and problems such as unstable control occur when θ increases.

  An object of the present invention is to provide a laser tracker that suppresses the occurrence of crosstalk and enables stable servo control when driving a drive source that causes a laser beam to follow the target when the target moves. .

The laser tracker according to the present invention is a laser tracker for obtaining a spatial coordinate of one target provided on a measurement object, the laser light source for irradiating the target with a laser beam, and the laser beam for the moving target. Angle adjusting means that can adjust the angle around two axes orthogonal to each other, a light receiving unit that recognizes position information of reflected light of the laser beam reflected by the target, and reflected light of the laser beam reflected by the target Measuring means for measuring the distance from the laser beam irradiated by the laser light source and the reflected light received to the target to the gain set in the variable gain setting unit from the position information recognized by the light receiving unit On the basis of the control means for controlling the angle by the angle adjusting means, and the angle adjusting means. Gain command means for calculating a crosstalk amount of two angle components of the laser beam in the light receiving unit from the angle information of the laser beam to be adjusted, obtaining a gain for canceling the crosstalk amount, and setting the gain in the variable gain setting unit; It is characterized by having.
The position information represents the amount of displacement of the laser spot in two orthogonal directions on the light receiving unit.

  According to this configuration, the laser beam emitted from the laser light source reaches the target via the angle adjusting means. The reflected light reflected by the target returns to the irradiation laser tracker through substantially the same path. The measuring means receives the reflected light and measures the distance from the laser beam irradiated by the laser light source and the received reflected light to the target. When the target moves, the control unit controls the angle by the angle adjustment unit based on the gain set in the variable gain setting unit from the movement amount of the locus of the laser beam recognized by the light receiving unit. This causes the laser beam to follow the target.

For example, when the target moves in the horizontal direction, the gain command unit calculates the crosstalk amount of two angle components of the laser beam trajectory in the light receiving unit from the angle information of the laser beam adjusted by the angle adjusting unit. When the angle information of the laser beam is the angle θ, the locus of the laser beam in the x direction and the y direction on the light receiving unit rotates by θ. Then, the trajectory of the laser beam in the x direction is decomposed into xcosθ and −xsinθ, and the trajectory of the laser beam in the y direction is decomposed into ycosθ and ysinθ, respectively.
Therefore, if the movement amount of the locus of the laser beam on the light receiving unit 6 is (x, y) and the conversion rate to voltage is e, the output (X, Y) of the light receiving unit 6 is

となる。この場合、ｘからＹへのクロストーク量、ｙからＸへのクロストーク量は、ゲイン指令手段によりそれぞれsinθと求められる。受光部等を同期回転する回転機構を有することなく、角度調整手段の角度調整に伴い、直交する各軸方向の信号を分離するために、式（２）の行列式の逆行例を求めると、

It becomes. In this case, the crosstalk amount from x to Y and the crosstalk amount from y to X are respectively determined as sin θ by the gain command means. In order to separate the signals in the directions of the orthogonal axes in accordance with the angle adjustment of the angle adjusting means without having a rotating mechanism for synchronously rotating the light receiving unit or the like, a reverse example of the determinant of the equation (2) is obtained.

となる。このように式（４）を適用することで、レーザービームをターゲットに追従させる場合に、クロストークの発生を抑え安定したサーボをかけることができる。

It becomes. By applying the formula (4) in this way, when the laser beam is made to follow the target, the occurrence of crosstalk can be suppressed and stable servo can be applied.

The variable gain setting unit may be a programmable gain amplifier, and the gain command means may command the obtained gain to the programmable gain amplifier.
The variable gain setting unit may be a multiplier, and the control unit may multiply the signal by a voltage corresponding to a gain using the multiplier.
The variable gain setting unit includes any one of a microcomputer, a personal computer, and a programmable logic controller (abbreviated as PLC), an AD converter, and a DA converter, and the control means is suitable for a signal input from the AD converter. It is also possible to output with a DA converter with a certain gain.

  The variable gain setting unit may be provided with a switch capable of changing the gain. For example, when using a plurality of switches, divide the angle with respect to the moving target into the same number of areas as the switches, and determine the gain in each switch so that the appropriate gain is obtained in each area. Switch to the specified switch.

The control means includes an angle detection means for detecting an angle of each axis of the angle adjustment means, and a feedback control unit for each axis for controlling the angle adjustment means using a detection value of the angle detection means, The variable gain setting unit may adjust the gain of the feedback control unit of each axis in addition to the gain change based on the angle information.
When the variable gain setting unit is used as an adjustment unit that adjusts the gain of the feedback control unit of each axis, the control unit may be configured to automatically change the gain by observing the state of the servo system. According to this configuration, when the servo seems to oscillate, the servo gain can be automatically changed to a smaller value to bring the servo in a stable direction.

  The laser tracker according to the present invention is a laser tracker for obtaining a spatial coordinate of one target provided on a measurement object, the laser light source for irradiating the target with a laser beam, and the laser beam for the moving target. Angle adjusting means that can adjust the angle around two axes orthogonal to each other, a light receiving unit that recognizes position information of reflected light of the laser beam reflected by the target, and reflected light of the laser beam reflected by the target Measuring means for measuring the distance from the laser beam irradiated by the laser light source and the reflected light received to the target to the gain set in the variable gain setting unit from the position information recognized by the light receiving unit On the basis of the control means for controlling the angle by the angle adjusting means, and the angle adjusting means. Gain command means for calculating a crosstalk amount of two angle components of the laser beam in the light receiving unit from the angle information of the laser beam to be adjusted, obtaining a gain for canceling the crosstalk amount, and setting the gain in the variable gain setting unit; Therefore, when the target moves, when driving a drive source that causes the laser beam to follow the target, generation of crosstalk can be suppressed and stable servo can be applied.

It is a figure which shows schematically the principle of the laser tracker which concerns on 1st Embodiment of this invention. It is a block diagram of the control system of the laser tracker concerning a reference proposal example. It is a block diagram of the control system of the laser tracker concerning a 1st embodiment of this invention. It is a figure which shows schematic structure in case the light-receiving part of the laser tracker consists of a 4-part photodiode. It is a figure showing the locus | trajectory of the laser beam on the light-receiving part of the laser tracker.

A first embodiment of the present invention will be described with reference to FIGS.
The laser tracker according to this embodiment follows the movement of one target provided on the measurement object and obtains spatial coordinates. The following description also includes a description of the spatial coordinate measurement method. As shown in FIG. 1, in this example, the target Tg is attached in a stationary state at one place on the measurement object W. As the target Tg, for example, a spherical retro reflector is used. However, it is not limited to a spherical retro reflector.

  The laser tracker 1 mainly includes a laser light source 2, an angle adjustment unit 3, a measurement unit 4, and a control unit 5. The laser light source 2 irradiates the target Tg with the laser beam Lb, and the measuring means 4 measures the distance to the target Tg using the laser beam Lb reflected by the target Tg. As the measuring means 4, for example, a length measuring device comprising an interferometer or an absolute distance meter is used. The laser light source 2 and the length measuring device constitute a laser length measuring device which is an integrated device and are accommodated in, for example, a cylindrical casing 6.

The angle adjusting means 3 is capable of adjusting the angle of the laser beam Lb around two orthogonal axes with respect to the moving target Tg, and includes an optical device.
The optical apparatus includes a half mirror 8, a θ-axis motor 9, a θ-axis encoder 10 that is an angle detection unit, a ψ-axis motor 11, a ψ-axis encoder 12 that is an angle detection unit, and a mirror 13. In the θ-axis motor 9 and the ψ-axis motor 11, the θ-axis (Y-axis) and the ψ-axis (X-axis) are two orthogonal axes, and the θ-axis is arranged in parallel to the axial center of the cylindrical casing 6. A θ-axis motor 9 and a θ-axis encoder 10 are provided at the upper end portion of the casing 6, and the rotating body 14 is supported via the θ-axis motor 9 so as to be rotationally driven.

  Therefore, the rotating body 14 is configured to be angularly displaceable about the θ axis relative to the casing 6 at the upper end portion of the casing 6. A θ-axis motor 11 and a θ-axis encoder 12 are supported on the upper end portion of the rotating body 14 via a concave frame 15. The axes of the ψ-axis motor 11 and the ψ-axis encoder 12 are parallel to the ψ axis orthogonal to the θ axis, and the mirror 13 is supported on the axes of the ψ-axis motor 11 and the ψ-axis encoder 12 so as to be angularly displaceable. ing. Note that a hole h through which a laser beam (including reflected light) Lb passes is formed in the upper end portion of the casing 6, the rotating body 14, and the frame 15.

  The laser beam Lb emitted from the laser light source 2 passes through the half mirror 8, is reflected by the mirror 13, and then reaches the target Tg. The laser beam Lb reflected by the target Tg, that is, the reflected light passes through substantially the same path, returns to the irradiation source laser tracker 1, is reflected by the half mirror 8, and reaches the light receiving unit 7 disposed in the casing 6. The light receiving unit 7 recognizes the position information of the reflected light of the laser beam Lb, that is, the positional deviation amount of the reflected light with respect to the reference position, and is, for example, a semiconductor position detecting element (abbreviated as PSD) or a quadrant photodiode. Composed. The “positional information” of the reflected light represents the displacement amount of the laser spot in the two orthogonal directions on the light receiving unit 7. The control means 5 controls the θ-axis motor 9 and the ψ-axis motor 11 so that the reflected light reaching the light receiving unit 7 returns to the center of the light receiving unit 7.

  For example, when the light receiving unit 7 is composed of a two-dimensional semiconductor position detecting element, the biaxial directions (X and Y axis directions) orthogonal to the reference position, such as the center position on the surface of the light receiving unit at the laser spot reaching the surface of the light receiving unit ), A current represented by coordinates (x, y) is obtained. X of coordinates (x, y) indicates only the amount of positional deviation in the X-axis direction among the laser spots on the surface of the light receiving unit, and y of coordinates (x, y) indicates Y of the laser spots on the surface of the light receiving unit. Only the axial displacement is shown. This current is converted into a voltage and input to a programmable gain amplifier 17 (FIG. 3) described later. When the laser beam Lb deviates from the center of the target Tg, the laser spot that reaches the surface of the light receiving unit deviates from the semiconductor position detecting element, and an error signal is generated. When the target Tg is moved to obtain a large number of spatial coordinates and the movement of the target Tg is tracked by the laser tracker 1, the center of each target Tg is tracked by the laser beam Lb based on the position data from the light receiving unit 7. obtain.

As shown in FIG. 4, when the light receiving unit 7 is composed of, for example, a four-division photodiode, a change in the barycentric position of the projected image of the laser spot that has reached the surface of the light receiving unit is measured. That is, the displacement is measured as a voltage from the differential output of the photodiode in each of the four divided regions. If the output (current value) of each of the four divided regions of the photodiode is A, B, C, D on the surface of the light receiving unit in the clockwise direction, the amount of positional deviation in the orthogonal biaxial direction with respect to the reference position on the surface of the light receiving unit Of these, the displacement in the X-axis direction is represented as (B + C)-(D + A), and the displacement in the Y-axis direction is represented as (A + B)-(C + D). These displacements in the X and Y axis directions are converted into voltages and input to the programmable gain amplifier 17 (FIG. 3), as in the case of the two-dimensional semiconductor position detecting element.
Part of the reflected light returning to the laser tracker 1 enters the length measuring device without being reflected by the half mirror 8, and this length measuring device receives the reflected light and projects the laser beam Lb emitted from the laser light source 2. And the distance from the received reflected light to the target Tg.

As shown in FIG. 3, the control unit 5 includes a gain command unit 16, a programmable gain amplifier 17 as a variable gain setting unit, a θ axis control unit 18, a ψ axis control unit 19, a θ axis driver 20, and a ψ-axis driver 21. These θ-axis control unit 18 and ψ-axis control unit 19 are constituted by, for example, a microcomputer or other electronic devices. The θ-axis control unit 18 and the ψ-axis control unit 19 respectively command the θ-axis driver 20 and the ψ-axis driver 21 so that the laser beam Lb always returns to the center of the light receiving unit based on the signals from the light receiving unit 7. The θ-axis motor 9 and the ψ-axis motor 11 angularly displace the mirror 13 around the orthogonal θ-axis and ψ-axis based on the command value. As a result, the mirror 13 is always directed in an appropriate direction. As a reference proposal example, FIG. 2 shows a block diagram of a laser tracker control system including a gain command means 16 and a control means not provided with the programmable gain amplifier 17. In this case, theta axis control unit 18, the [psi axis control unit 19, respectively, fixed gain kappa _theta, kappa _[psi is set. The control means of this reference proposal example uses the gains Κ _θ and Κ _ψ for the output (X, Y) obtained by converting the positional deviation amount (current) of the laser spot that has reached the surface of the light receiving portion into a voltage, and adjusts the angle. The angle by means 3 is controlled.

As shown in FIG. 1, a calculation means 22 is electrically connected to the length measuring device, the θ-axis encoder 10 and the ψ-axis encoder 12. The computing means 22 obtains the spatial coordinates of the target Tg from the measured value of the distance to the target Tg measured by the length measuring instrument and the measured values of the θ-axis encoder 10 and the ψ-axis encoder 12.
In order to measure the shape of the workpiece W, it is necessary to obtain a large number of spatial coordinates. Therefore, the target Tg is moved manually or automatically, and the laser tracker 1 is tracked to the movement of the target Tg. That is, the angle of the laser beam Lb is displaced with respect to the moving target Tg, and the target Tg at each position is irradiated with the laser beam Lb.

  In the embodiment of the present invention, the laser tracker 1 is not provided with a rotation mechanism for synchronously rotating the light receiving unit or the like, and the signals in the orthogonal θ and ψ axial directions are separated as the θ axis motor 9 rotates. The control circuit shown in FIG. 2 has a structure that can apply Equation (4) to be described later so that stable servo can be applied. As a result, as shown in FIG. 3, the gain command means 16 and the programmable gain amplifier 17 are provided on the circuit. The programmable gain amplifier 17 is an amplifier whose amplification factor is variable according to the gain input from the gain input terminal. A θ-axis control unit 18 and a ψ-axis control unit 19 are electrically connected to the subsequent stage of the light receiving unit 7 via a programmable gain amplifier 17. A programmable gain amplifier 17 is electrically connected to the θ-axis encoder 10 that is an angle detection unit of the angle adjustment unit 3 via a gain command unit 16.

For example, when the target Tg moves in the horizontal direction, the gain command means 16 determines the angle in the biaxial direction perpendicular to the reference position on the surface of the light receiving unit of the laser beam Lb in the light receiving unit 7 from the measured value of the angle of the θ-axis encoder 10. The amount of crosstalk between two angle components is calculated as the amount of displacement. When the measured value of the angle of the laser beam Lb is θ, as shown in FIG. 5, the locus of the laser beam Lb in the X-axis direction and the Y-axis direction on the light-receiving unit 7, that is, the reference of the laser spot on the surface of the light-receiving unit The amount of displacement relative to the position rotates by θ. Then, the coordinate x of the laser beam Lb in the X-axis direction is decomposed into xcosθ and −xsinθ, and the coordinate y of the laser beam Lb in the Y-axis direction is decomposed into ycosθ and ysinθ, respectively.
Therefore, assuming that the coordinate which is the positional deviation amount with respect to the reference position of the laser beam Lb on the light receiving unit 7 is (x, y) and the conversion rate to voltage is e, the output (X, Y) of the light receiving unit 7 is

となる。この場合、ｘからＹへのクロストーク量、ｙからＸへのクロストーク量は、ゲイン指令手段によりそれぞれsinθと求められる。受光部等を同期回転する回転機構を持たせずに、θ軸モータ９の回転に伴い、直交するθ方向，ψ方向の信号を分離するために、式（２）の行列式の逆行列を求めると、

It becomes. In this case, the crosstalk amount from x to Y and the crosstalk amount from y to X are respectively determined as sin θ by the gain command means. In order to separate the orthogonal θ direction and ψ direction signals with the rotation of the θ-axis motor 9 without having a rotating mechanism for synchronously rotating the light receiving unit or the like, an inverse matrix of the determinant of Equation (2) is used. When asked

と表される。

It is expressed.

  The gain command means 16 determines the gain of the A1 amplifier as a1, the gain of the A2 amplifier as a2, and the gain of the A3 amplifier as a3 in the programmable gain amplifier 17 according to the above equation (4) from the measured value of the θ angle of the θ-axis encoder 10. , Command the gain of the A4 amplifier as a4. Each gain is

となる。このように式（４）を適用することで、レーザービームをターゲットに追従させる場合に、クロストークの発生を抑え安定したサーボをかけることができる。

It becomes. By applying the formula (4) in this way, when the laser beam is made to follow the target, the occurrence of crosstalk can be suppressed and stable servo can be applied.

Another embodiment of the present invention will be described.
In the following description, the same reference numerals are given to the portions corresponding to the matters described in the preceding forms in each embodiment, and the overlapping description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those described in the preceding section. Not only the combination of the parts specifically described in each embodiment, but also the embodiments can be partially combined as long as the combination does not hinder.

A multiplier may be provided instead of the programmable gain amplifier, and the control means 5 may multiply the signal by a voltage corresponding to the gain using the multiplier.
Instead of the programmable gain amplifier, any one of a microcomputer, a personal computer, and a programmable logic controller (abbreviated as PLC), an AD converter, and a DA converter are provided, and the control means 5 receives the signal input from the AD converter. Alternatively, an appropriate gain may be given and output by a DA converter.

Instead of the programmable gain amplifier, a switch capable of changing the gain may be provided. For example, when a plurality of switches are provided, the angle θ with respect to the moving target Tg is divided into the same number of areas as the switches, and the gain in each switch is determined so as to obtain an appropriate gain in each area. Switch to the specified switch every time.
Specifically, first, the measurement space is divided into several to several tens of areas based on the distance to the target Tg. When irradiating the laser beam Lb at an arbitrary position of the target Tg, the calculation means 22 specifies an existing area from the measured value of the distance to the target Tg measured by the length measuring device. Thereby, it switches to the switch linked | related with the specified area.

  In addition, a gain is determined for each switch, whereby the θ-axis control unit 18 and the ψ-axis control unit 19 adjust the laser beam that is adjusted by the angle adjusting unit 3 with respect to the θ-axis driver 20 and the ψ-axis driver 21, respectively. A command based on the servo gain that takes into account the angle information of Lb is given. The θ-axis motor 9 and the ψ-axis motor 11 angularly displace the mirror 13 around the orthogonal θ-axis and ψ-axis based on the command value. Therefore, the laser tracker 1 having a servo system in which the angle information of the laser beam Lb is added to the target Tg can be realized.

As yet another embodiment, the programmable gain amplifier 17 may be used not only as a gain change based on the angle information of the laser beam Lb but also as an adjusting means for adjusting the servo gain itself. That is, the control means 5 detects the angle of each axis (θ axis, ψ axis) of the angle adjusting means 3 and the detected values of the θ axis encoder 10, the ψ axis encoder 12, and the θ axis encoder 10, the ψ axis encoder 12. The gain of the θ axis and ψ axis feedback control units for controlling the angle adjusting means 3 may be adjusted.
In this case, if the servo gains of the θ-axis and the ψ-axis are g _θ and g _ψ , the overall gain is expressed by the following equation (7).

  When the programmable gain amplifier 17 is used as an adjustment unit that adjusts the gain of the feedback control unit of each axis, the control unit 5 may be configured to automatically change the gain by observing the state of the servo system. According to this configuration, when the servo seems to oscillate, the servo gain g can be automatically changed to a small value to bring the servo in a stable direction.

DESCRIPTION OF SYMBOLS 1 ... Laser tracker 2 ... Laser light source 3 ... Angle adjustment means 4 ... Measurement means 5 ... Control means 7 ... Light-receiving part 16 ... Gain command means 17 ... Programmable gain amplifier Lb ... Laser beam Tg ... Target W ... Measurement object

Claims (7)

A laser tracker for obtaining a spatial coordinate of one target provided on a measurement object,
A laser light source for irradiating the target with a laser beam;
Angle adjusting means capable of adjusting the angle of the laser beam about two axes orthogonal to the moving target;
A light receiving unit for recognizing position information of reflected light of a laser beam reflected by the target;
Measuring means for receiving reflected light of the laser beam reflected by the target and measuring a distance from the laser beam irradiated by the laser light source and the received reflected light to the target;
Control means for controlling the angle by the angle adjusting means based on the gain set in the variable gain setting section from the position information recognized by the light receiving section;
The crosstalk amount of two angle components of the laser beam in the light receiving unit is calculated from the angle information of the laser beam adjusted by the angle adjusting means, and a gain for canceling the crosstalk amount is obtained and set in the variable gain setting unit A laser tracker comprising gain command means.   2. The laser tracker according to claim 1, wherein the variable gain setting unit is a programmable gain amplifier, and the gain command means commands the gain obtained to the programmable gain amplifier.   2. The laser tracker according to claim 1, wherein the variable gain setting unit is a multiplier, and the control unit multiplies the signal by a voltage corresponding to a gain using the multiplier.   2. The variable gain setting unit according to claim 1, wherein the variable gain setting unit includes any one of a microcomputer, a personal computer, and a programmable logic controller, an AD converter, and a DA converter. A laser tracker that has an appropriate gain and outputs with a DA converter.   2. The laser tracker according to claim 1, wherein the variable gain setting unit is a switch capable of changing a gain.   2. The control unit according to claim 1, wherein the control unit detects an angle of each axis of the angle adjusting unit, and a feedback control unit for each axis controls the angle adjusting unit using a detection value of the angle detecting unit. And the variable gain setting unit adjusts the gain of the feedback control unit of each axis in addition to the gain change by the angle information.   7. The laser tracker according to claim 6, wherein the control means observes the state of the servo system and can automatically change the gain.

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