JP2001091891A - Irradiation position control method and device for wedge prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an irradiation position control method for wedge prisms which are capable of surely bringing the irradiation position of the light deflected by the wedge prisms to the center of a photodetector by taking the characteristics of the wedge prisms into consideration. SOLUTION: A stage (S4) for rotating a pair of the wedge prisms 1 and 2 while maintaining a differential angle Δψ of a pair of the wedge prisms 1 and 2 constant and a stage (S5) of changing the differential angle Δψ are incorporated into the irradiation position control method for the wedge prisms. When a pair of the wedge prisms 1 and 2 are rotated while the differential angle Δψis maintained constant, the irradiation position Q draws a circular locus and therefore the angle of the plane polar coordinates of the irradiation position Q and the center O of the photodetector 7 may be aligned. The distance from the center O of the photodetector 7 to the irradiation position Q may be made smaller by changing the differential angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wedge prism irradiation position control method and apparatus for controlling the irradiation position of deflected light by controlling the rotation angle of a pair of wedge prisms.

[0002]

2. Description of the Related Art Wedge prisms for use in beam manipulation in optical systems are known. FIG.
Indicates a wedge prism 1. (A) in the figure
Shows a plan view of the wedge prism 1, and (b) shows a main cross section (a cross section perpendicular to the ridge line S) of the wedge prism 1. The wedge prism 1 is a thin prism lens having a small apex angle (wedge angle) w, and deflects the beam at a declination δ when the beam is vertically incident on the first surface of the wedge prism 1.

FIG. 12 shows two wedge prisms 1 and 2.
2 shows the beam deflection in the case of combining. When the two wedge prisms 1 and 2 are arranged close to each other and the two wedge prisms 1 and 2 are separately rotated around the central axis, a beam is emitted in an arbitrary direction inside a predetermined sharp cone. It deflects and can illuminate any position on the plane 3 which is the bottom surface of the cone.

[0004]

Here, when a light receiver is arranged at the irradiation position Q and the light irradiation position is controlled so that the irradiation position Q is located at the center of the light receiver even when the light receiver moves, a wedge prism is provided. The displacement of the light receiver that has moved can be known from the rotation angles 1 and 2.

Therefore, the present invention considers the characteristics of a wedge prism, and allows the irradiation position of the light deflected by the wedge prism to be reliably brought to a target (the center of the light receiver). It is an object to provide a control method and device.

[0006]

Hereinafter, the present invention will be described. In addition, in order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are added in parentheses, but the present invention is not limited to the illustrated embodiment.

To solve the above problems, the present inventor has
When the rotation is performed while the difference angle (relative angle) between the pair of wedge prisms (1, 2) is kept constant, the irradiation position is defined by the extension of the center line of the wedge prism (1, 2) and the plane on which the target is arranged. Drawing a circular locus about the intersection (P),
When the difference angle is changed by rotating the pair of wedge prisms (1, 2) by the same angle in the opposite direction, the irradiation position focuses on drawing a substantially linear trajectory passing through the intersection (P). Q) was compared with the target (O), and the irradiation position (Q) was moved in the plane polar coordinate r, ψ directions so that the irradiation position (Q) coincided with the target (O). That is, the invention of claim 1 provides a pair of wedge prisms (1,
2) An irradiation position control method of a wedge prism for controlling an irradiation position (Q) of light deflected by the pair of wedge prisms by operating a rotation angle of the pair of wedge prisms. The difference angle of (1, 2) (Δ
a method of controlling the irradiation position of the wedge prism, comprising: a step of rotating the pair of wedge prisms (1, 2) while maintaining the constant ψ); and a step of changing the difference angle (Δψ). Has solved the above-mentioned problem.

According to the present invention, when the wedge prisms (1, 2) are rotated with the difference angle (Δψ) kept constant, the irradiation position (Q) becomes a circular locus about the intersection (P). , The angle ψ of the plane polar coordinates of the irradiation position (Q) and the target (O) can be matched. Next, the distance between the target (O) and the irradiation position (Q) can be reduced by changing the difference angle (Δψ). Therefore, the irradiation position (Q) can be brought to the target (O).

In order to solve the above-mentioned problem, the invention according to claim 2 calculates the first position vector (v1) detected by the light receiver (7) and the rotation angle of the wedge prism (1, 2). According to the second position vector (v0), the rotation angle of the wedge prism (1, 2) is determined so that the irradiation position (Q) is located at the center (O) of the light receiver (7). Specifically, the rotation position of the pair of wedge prisms (1, 2) is operated to control the irradiation position of the light deflected by the pair of wedge prisms (1, 2) on the light receiver (7). An irradiation position control method for a wedge prism, wherein a center (O) of the light receiver (7) is a starting point,
A detecting step (S3) of detecting a first position vector (v1) having the irradiation position (Q) as an end point; a line extending a center line of the pair of wedge prisms (1, 2); 7) calculating the second position vector (v0) starting from the intersection (P) with the irradiation position (Q) and ending from the rotation angle of the pair of wedge prisms (1, 2) ( S2) and the first position vector (v
1) and according to the second position vector (v0),
An angle determining step (S4, S5) for determining a rotation angle of the pair of wedge prisms (1, 2) such that the irradiation position (Q) is located at the center (O) of the light receiver (7). It is characterized by. Here, a photosensor such as a two-axis photoelectric sensor or an imaging element such as a CCD camera can be used as the light receiver (7).

According to a third aspect of the present invention, in the second aspect, the wedge prism angle determining step (S4, S4
5) the pair of wedge prisms (っ た) having a constant difference angle (（) so that the direction of the first position vector (v1) matches the direction of the second position vector (v0). A direction angle determining step (S4) for determining the rotation angle of (1, 2), and a difference angle between the pair of wedge prisms (1, 2) such that the absolute value of the first position vector (v1) is reduced. (Δψ) difference angle determination step (S
5).

According to the present invention, the direction angle determining step (S
In 4), the rotation angle of the wedge prism that matches the direction (the angle で in plane polar coordinates) between the first position vector (v0) and the second position vector (v1) is determined. Then, in the difference angle determination step (S4), the first position vector (v
Wedge prism (1, 2) for reducing absolute value of 0)
Is determined (Δψ). Therefore, the irradiation position (Q) can be brought to the center (O) of the light receiver (7).

According to a fourth aspect of the present invention, in the wedge prism irradiation position control method according to the second or third aspect, the calculating step includes the step of determining the declination δ1, δ2 and the angle of each of the pair of wedge prisms (1, 2). Detecting means (12a, 12
The rotation angles ψ1, ψ2 of each of the pair of wedge prisms (1, 2) obtained by b) and the distance L from the wedge prism (1, 2) to the light receiver (7) are input, and the following calculation is performed. The coordinates (X, Y) of the end point of the second position vector are calculated using an equation.

X = (δ1cosψ1 + δ2cosψ2) × L Y = (δ1sinψ1 + δ2sinψ2) × L Generally, it is difficult to calculate the irradiation position (Q) strictly when the wedge prisms (1, 2) are combined. When the light deflected by the wedge prism (1) is incident on the wedge prism (2), it is incident as a beam (skew beam) that is not in the main section, and the refraction of the skew beam is considerably complicated. is there. The present inventor has found that the wedge prisms (1, 2) are prisms having a small apex angle, the declinations δ1, δ2 are minute, and the wedge prisms (1, 2) to be combined are arranged close to each other. For this reason, the irradiation position (Q) was calculated using the above simple calculation formula.

According to a fifth aspect of the present invention, the rotation angle of the pair of wedge prisms (1, 2) is manipulated so that the light deflected by the pair of wedge prisms (1, 2) on the light receiver (7). An irradiation position control device for a wedge prism for controlling an irradiation position (Q), wherein a first position vector (A) having a center (O) of the light receiver (7) as a start point and an irradiation point (Q) as an end point. v1) a detection means, an intersection (P) between a line extending the center line of the pair of wedge prisms (1, 2) and the light receiver (7) as a starting point, and the irradiation position (Q) as an end point. Calculating means for calculating a second position vector (v0), and a center (O) of the light receiver (7) according to the first position vector (v1) and the second position vector (v0). The pair of wedges is positioned so that the irradiation position (Q) comes. The irradiation position control device of the wedge prisms, characterized in that it comprises a rotational angle determining means for determining a rotation angle of the prism, and solve the problems described above.

According to the present invention, the photodetector (7) is provided in accordance with the detected first position vector (v1) and the second position vector (v0) calculated from the rotation angle of the wedge prism (1, 2). The rotation angle of the wedge prism (1, 2) is determined so as to bring the irradiation position to the center of
The irradiation position (Q) can be brought to the center (O) of the light receiver (7) by operating the rotation angle of the wedge prisms (1, 2).

According to a sixth aspect of the present invention, in the method for controlling the irradiation position of the wedge prism according to the fifth aspect, the rotation angle determining means includes a direction of the first position vector (v1) and a direction of the second position vector. A direction angle determining means for determining the rotation angle of the pair of wedge prisms (1, 2) while keeping the difference angle (Δψ) constant so that the direction of (v0) coincides with the first position vector ( and a difference angle determining means for determining a difference angle (Δψ) between the pair of wedge prisms (1, 2) such that the absolute value of v1) is reduced.

According to the present invention, the first position vector (v1) and the second position vector (v1) are determined by the direction angle determining means.
(The rotation angle 平面 in the plane polar coordinates) is determined to determine the rotation angle of the wedge prism (1, 2). Then, the difference angle (Δ) of the wedge prisms (1, 2) for reducing the absolute value of the first position vector (v1) by the difference angle determining means.
ψ) is determined. Therefore, the rotation angle of the wedge prism (1, 2) that brings the irradiation position (Q) to the center (O) of the light receiver (7) can be determined.

According to a seventh aspect of the present invention, in the wedge prism control device according to the fifth or sixth aspect, the arithmetic means includes: a pair of wedge prisms (1, 2); The rotation angles ψ1, 取得 2 of the pair of wedge prisms (1, 2) acquired by (12a, 12b) and the distance L from the wedge prism (1, 2) to the light receiver (7) are input, The coordinates (X0, Y0) of the end point of the second position vector are calculated using the following formula.

X0 = (δ1cosψ1 + δ2cosψ2) × L Y0 = (δ1sinψ1 + δ2sinψ2) × L The wedge prism is a prism having a small apex angle and a declination δ
Are very small, and the wedge prisms to be combined are arranged close to each other, so that the irradiation position can be calculated using the above-mentioned simple formula.

[0020]

FIG. 1 shows a system configuration diagram in which a wedge prism irradiation position control device according to a first embodiment of the present invention is incorporated. The system includes a laser sighting device 5 that emits laser light, a prism unit 6 that deflects the laser light, a light receiver 7 that is irradiated with the deflected laser light, and a light receiver 7 that emits light.
An irradiation position control device 8 (software servo) for operating the prism unit 6 so as to be located at the center of the light source, and a computer 9 such as a personal computer for calculating the displacement of the light receiver 7 from the rotation angles of the wedge prisms 1 and 2. ing. The laser light emitted from the laser sighting device 5 is deflected by the prism unit 6 and irradiates the center of the light receiver 7. The irradiation position control device 8 controls the rotation angles of the wedge prisms 1 and 2 so that the deflected laser light automatically irradiates the center of the light receiver 7. Further, a distance measuring means 15 such as a range finder measures the distance L from the prism unit 6 to the light receiver 7. In the present embodiment, the displacements (X0, Y0), (X0 ', Y0'),
Switching means 1 for measuring (X0 ″, Y0 ″)
0 is provided, and the target light receiver 7 is switched.

FIG. 2 shows the prism unit 6. This prism unit 6 deflects a laser beam emitted from a laser sighting machine in an arbitrary direction.
A cylindrical case 14, a pair of wedge prisms 1 and 2 rotatably provided in the case 14, motors 11a and 11b as driving units for individually rotating the wedge prisms 1 and 2, and a wedge prism Encoders 12a and 12b are provided as angle detecting means for digitally detecting the rotation angles 1 and 2. Motor 1
1a, 11b and the encoders 12a, 12b are integrated. The wedge prisms 1 and 2 are covered with a protective glass 13 to prevent dust and the like from adhering.

FIG. 3 shows a main section of the combined wedge prisms 1 and 2. The wedge prisms 1 and 2 are thin, substantially cylindrical prism lenses having a small apex angle (wedge angle) w. When the laser light is deflected only by the wedge prism 1, it is assumed that the laser light is vertically incident on the first surface of the wedge prism 1.
Is represented by the following general formula.

[0023]

(Equation 1)

Assuming that w is small, δ−１ (n−1) w where n is the refractive index.

The two combined wedge prisms 1,
2 are of the same material and have the same wedge apex angle w.
The pair of wedge prisms 1 and 2 independently rotate around the center line, and the laser beam enters from the center line. When the two wedge prisms 1 and 2 are disposed close to each other so that the inclined surfaces 7 are parallel, the laser beam that has passed through the wedge prisms 1 and 2 travels straight in the same way as passing through parallel glass. On the other hand, by separately rotating around the center lines of the wedge prisms 1 and 2, the laser light can be deflected in an arbitrary direction inside a predetermined sharp cone.

FIG. 4 shows the refraction of laser light by the wedge prisms 1 and 2 in a coordinate system. Here, on the optical path of the incident laser light, that is, the wedge prisms 1 and 2
Are taken on the Z axis, and the XY plane is taken on a plane orthogonal to the center lines of the wedge prisms 1 and 2. Also, X
In the Y plane, the X axis is taken in the horizontal direction and the Y axis is taken in the vertical direction. As shown in this figure, when laser light is incident on the center line of the wedge prisms 1 and 2, the wedge prism 1 deflects the laser light and the wedge prism 2
Further deflects the laser light. Here, the declination of the wedge prism 1 is δ1, the polarization direction is ψ1, the declination of the wedge prism 2 is δ2, and the deflection direction is ψ2. The polarization directions ψ1 and ψ2 of the wedge prisms 1 and 2 are 0 degrees when the deflection direction is located on the XZ plane, and the angles from this position are represented by ψ1 and ψ2. The deflection directions ψ1 and ψ2 are
It is obtained from the rotation angles ψ1 and ψ2 of the wedge prisms 1 and 2, respectively. When the line connecting the thickest part and the thinnest part of each wedge prism 1 and 2 is horizontal (X
Is set to 0 degrees, and angles from this position are represented by ψ1 and ψ2.

Declination angle δ of each of wedge prisms 1 and 2
1, δ2, the rotation angles ψ1, ψ2 of each of the wedge prisms 1 and 2 obtained by the encoder, and the distance L measured by the angle measuring means are input to the irradiation position control device 8, and the combined displacement (X0 , Y0) are calculated by the irradiation position control device 8. Where wedge apex w
Is small, so that δ1,
It is assumed that both δ2 are minute and wedge prism 1 and wedge prism 2 are close to each other. And
Deflection vector (declination δ when only wedge prism 1 is used)
1, deflection direction ψ1), and the deflection vector (deflection angle δ2, deflection direction ψ2) in the case of only wedge prism 2 as XY.
Display the vector in the coordinate system, add the two vectors together,
The resultant displacement (X0, Y0), the resultant deflection angle δT, and the resultant deflection direction ΔT are calculated. When the wedge prisms 1 and 2 having different declinations are used, a plurality of declinations are stored in the memory of the irradiation position control device 8.

FIG. 5A shows a deflection vector by the wedge prism 1 and FIG. 4B shows a deflection vector by the wedge prism 2. From this figure (a), the following formula is established for the wedge prism 1.

[0029]

(Equation 2)

Similarly, the following calculation formula holds for the wedge prism 2 as well.

[0031]

(Equation 3)

From equations 2 and 3, X of the deflection vector when wedge prism 1 and wedge prism 2 are summed up
The combined component δTX in the direction is represented by the following Expression 4.

[0033]

(Equation 4) Similarly, the composite component δTY in the Y direction is represented by the following Expression 5.

[0034]

(Equation 5)

The beam irradiation position (X0, Y0) on the XY plane at a distance L from the prism unit is X
0 = L × δTX, Y0 = L × δTY.

The combined deflection angle δT and the combined deflection direction ΔT are represented by the following equation (6).

[0037]

(Equation 6)

Here, the difference angle Δψ between the two wedge prisms
Is Δψ = ψ1-ψ2, δT is expressed by the following equation 7.

[0039]

Equation 7

From Equation 7, it can be seen that the combined argument δT is a function of only the difference angle. Further, by using these formulas, the combined displacement (X0, Y0) and the combined declination δ when combined from the rotation angles of the two wedge prisms.
T and the combined deflection direction ΔT can be easily calculated.

The irradiation position control device 8 controls the rotation angles of the wedge prisms 1 and 2 so that the laser beam deflected by the prism unit 6 automatically comes to the center of the light receiver 7 as described above.

The algorithm of the irradiation position control device 8 (software servo) will be described. This software servo feeds back the output value of the light receiver 7 so that the laser beam irradiates the center of the light receiver 7 and controls the rotation angle of the wedge prisms 1 and 2.

FIG. 6 shows a flowchart of the algorithm. First, it is determined whether or not the input level from the light receiver 7 is equal to or higher than e1 (step S1). In the case of a two-axis photoelectric sensor in which the photodetector 7 is a combination of four photoelectric sensors extending in four directions of + X, -X, + Y, and -Y from the center, the output value is close to 0 when the laser beam is at the center. If the input level from the light receiver 7 <e <b> 1, it is determined that the laser beam is at the center of the light receiver 7 and the rotation angles of the wedge prisms 1 and 2 are not operated. When the input level from the light receiver 7 ≧ e1, it is determined that the laser beam is not at the center of the light receiver 7, and the rotation angles of the wedge prisms 1 and 2 are operated as described below so as to be at the center.

As shown in FIGS. 7 and 8, first, a v1 vector is detected as a first position vector starting from the center O of the light receiver 7 and ending at the irradiation position Q. That is, the displacement (X1, Y1) is detected from the output value of the light receiver in the light receiver coordinate system having the center O as the origin (step S).
2). Then, the direction θ1 of the v1 vector is calculated from the calculation formula θ1 = tan ⁻¹ (Y1 / X1). Next, a v0 vector as a second position vector having a point of intersection P between the line extending the center line of the pair of wedge prisms and the light receiver as a start point and an irradiation position Q as an end point is used as a pair of wedge prisms 1 and 2. It is calculated from the rotation angle (step S3). X0 and Y0 respectively represent the X-direction component and the Y-direction component of the v0 vector of the prism coordinate system.
L, Y0 = δTY × L is calculated. Then, the direction ΔT of the v0 vector is calculated from Expression 6 described above. Here, the prism coordinate system refers to a coordinate system having an origin at an intersection P intersecting a plane on the light receiver 7 by extending the prism center line from the prism unit 6, and the light receiver coordinate system is a center O of the light receiver 7.
Means a coordinate system with the origin as.

In order for the laser beam to irradiate the center O of the light receiver 7, the v1 vector only needs to be 0. When the accuracy of the light receiver 7 is high and the coordinates X1 and Y1 are obtained with high accuracy, the rotation angles of the wedge prisms 1 and 2 are adjusted based on the X1 and Y1 so that the irradiation position is located at the center O of the light receiver 7. Although the accuracy may be determined, generally, the accuracy of the light receiver 7 is not so high. Therefore, the following process for bringing the irradiation position Q closer to the center O of the light receiver 7 is required. As a method of approaching, the displacements (r, ψ) in the plane polar coordinates of the v0 vector and the v1 vector are compared, and the directions ψ are first matched, and then v1
A method of setting the absolute value | r | of the vector to 0 is adopted.

First, the direction ψT of the v0 vector is compared with the direction θ1 of the v1 vector, and the two wedge prisms are simultaneously turned in the same direction while keeping the difference angle Δ 一致 constant.
T is changed (step S4). As shown in FIG. 9, when the two wedge prisms 1 and 2 are simultaneously turned while the difference angle Δψ between the two wedge prisms 1 and 2 is kept constant, the irradiation position Q keeps the absolute value of the v0 vector constant. Draw a circular trajectory centered on the origin point P. When the two wedge prisms 1 and 2 are simultaneously turned until the quadrant of T and θ1 and the angle become equal (from the position indicated by the two-dot chain line to the position indicated by the solid line in the figure), the angle ψ in the plane polar coordinates coincides, The v1 vector and the v0 vector overlap. Here, the amount of one rotation of the wedge prisms 1 and 2 is set to, for example, の of the difference so as not to vibrate.

Next, | v1 | is compared with | v0 |
With the angle kept constant, the difference angle Δ is set so that | v1 |
ψ changes. As shown in FIG. 10, when the two wedge prisms are rotated by the same amount in opposite directions, the irradiation position Q
Draws a substantially linear trajectory passing through the intersection P, and the v0 vector changes its absolute value while keeping ΔT substantially constant. As shown in this figure, the difference angle Δψ between two wedge prisms is | v
When 1 | is changed to 0, the absolute value of the v0 vector changes from the position indicated by the two-dot chain line to the position indicated by the solid line in FIG.
The irradiation position Q moves to the center O of the light receiver. | V1 | and |
By comparing v0 |, it is possible to know whether to increase or decrease the difference angle Δψ so that | v1 | Here, | v1 | = √ (X1 ² + Y
1 ² ), | v0 | = L√ (δTX ² + δTY ² ). The amount of change of the difference angle Δψ at one time is set to, for example, の of the difference so as not to vibrate.

Next, it is determined whether or not the amount of change in the difference angle Δψ in step S5 is, for example, 10 ″ or less (step S6). And returns to the start. 10 "
If not, repeat steps 2 to 5,
The rotation angles of the wedge prisms 1 and 2 are again operated so that the v1 vector becomes 0 again.

As described above, the irradiation position Q can be brought to the center O of the light receiver 7 by manipulating the rotation angle of the wedge prism. If the displacement (X0, Y0) of the irradiation position 9 in the prism coordinate system at this time is calculated from X0 = δTX × L and Y0 = δTY × L using the computer 9, the displacement of the center O of the light receiver 7 is obtained. You can know.

In the above embodiment, two light receivers are used.
Although the case where the axial photoelectric sensor is used has been described, an imaging element such as a CCD camera may be used as the light receiver. In this case, light emitted from a point light source such as a pencil light is refracted by the prism unit 6 and the visual information of the target is converted to C light.
The pattern is recognized by the CD camera, and the first position vector is detected from the recognized value.

[0051]

As described above, according to the present invention,
The method of controlling the irradiation position of the wedge prism includes a step of rotating the pair of wedge prisms while keeping a difference angle between the pair of wedge prisms constant, and a step of changing the difference angle. First, when the pair of wedge prisms is rotated while the difference angle between the pair of wedge prisms is kept constant, the irradiation position is a circular shape centered on the intersection of the extension of the center line of the wedge prism and the plane where the target is placed. Therefore, the irradiation position and the angle of the target plane polar coordinate can be matched. Next, by changing the difference angle, the distance from the target to the irradiation position can be reduced. Therefore, the irradiation position can be set at the target.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram incorporating a wedge prism irradiation position control device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a prism unit.

FIG. 3 is a sectional view showing a combined wedge prism.

FIG. 4 is a diagram showing deflection of a beam in an XYZ coordinate system.

FIG. 5 is a view showing a deflection vector ((a) in the figure shows a prism 1, and (b) in the figure shows a prism 2).

FIG. 6 is a flowchart showing an algorithm of software servo.

FIG. 7 is a diagram showing an irradiation position of a laser beam on a light receiver.

FIG. 8 is a diagram showing a prism coordinate system and a light receiver coordinate system.

FIG. 9 is a diagram showing a prism coordinate system and a light receiver coordinate system.

FIG. 10 is a diagram showing a prism coordinate system and a light receiver coordinate system.

FIGS. 11A and 11B are views showing a wedge prism (FIG. 11A is a plan view, and FIG. 11B is a main cross-sectional view).

FIG. 12 is a perspective view showing deflection of a combined wedge prism.

[Explanation of symbols]

 1, 2 Wedge prism 7 Light receiver 12a, 12b Encoder (angle detection means) Δψ Difference angle O Center of light receiver P Intersection Q Irradiation position v1 First position vector v0 Second position vector S3 Detection step S4 Direction angle determination step (Angle determination step) S5 Difference angle determination step (angle determination step)

Claims (7)

[Claims] 1. A wedge prism irradiation position control method for controlling a rotation position of a pair of wedge prisms to control an irradiation position of light deflected by the pair of wedge prisms. An irradiation position control method for a wedge prism, comprising: a step of rotating the pair of wedge prisms while keeping the difference angle constant; and a step of changing the difference angle. 2. A wedge prism irradiation position control method for controlling an irradiation position of a light deflected by the pair of wedge prisms on a light receiver by operating a rotation angle of the pair of wedge prisms. With the center of the device as a starting point, a detection step of detecting a first position vector having the irradiation position as an end point, and an intersection of the line extending the center line of the pair of wedge prisms and the light receiver as a starting point, A calculation step of calculating a second position vector having an irradiation position as an end point from the rotation angles of the pair of wedge prisms, and according to the first position vector and the second position vector, the center of the light receiver. Determining an angle of rotation of the pair of wedge prisms so that the irradiation positions come. Law. 3. The rotation angle of the pair of wedge prisms having a constant difference angle so that the direction of the first position vector coincides with the direction of the second position vector. And a difference angle determining step of determining the difference angle between the pair of wedge prisms so that the absolute value of the first position vector is reduced. Item 3. An irradiation position control method for a wedge prism according to Item 2. 4. The calculating step includes calculating the declination angles δ1, δ2 of each of the pair of wedge prisms, the rotation angles ψ1, ψ2 of each of the pair of wedge prisms obtained by the angle detecting means, and the pair of wedge prisms. The distance L to the light receiver is input, and the coordinates (X0, Y0) of the end point of the second position vector are calculated using the following formula.
The irradiation position control method for a wedge prism according to claim 2 or 3, wherein is calculated. X0 = (δ1cosψ1 + δ2cosψ2) × L Y0 = (δ1sinψ1 + δ2sinψ2) × L 5. An irradiation position control device for a wedge prism for controlling an irradiation position of a light deflected by the pair of wedge prisms on a light receiver by manipulating a rotation angle of the pair of wedge prisms. A detection unit for detecting a first position vector having the center of the light source as a starting point and the irradiation position as an end point, and an intersection of a line extending a center line of the pair of wedge prisms and a light receiver as a starting point, the irradiation being performed. Calculating means for calculating a second position vector having a position as an end point, and the pair of the first position vector and the second position vector so that the irradiation position comes to the center of the light receiver in accordance with the second position vector. A rotation angle determining means for determining a rotation angle of the wedge prism. 6. The rotation angle determining means is configured to rotate the pair of wedge prisms while maintaining a constant difference angle such that a direction of the first position vector coincides with a direction of the second position vector. A directional angle determining means for determining an angle, and a difference angle determining means for determining the difference angle between the pair of wedge prisms so that an absolute value of the first position vector is reduced. 6. The irradiation position control device for a wedge prism according to 5. 7. The calculating means calculates a declination angle δ1, δ2 of each of the pair of wedge prisms, a rotation angle ψ1, ψ2 of each of the pair of wedge prisms obtained by an angle detecting means, and the pair of wedge prisms. The distance L to the light receiver is input, and the coordinates (X0, Y0) of the end point of the second position vector are calculated using the following formula.
The wedge prism control device according to claim 5 or 6, wherein is calculated. X0 = (δ1cosψ1 + δ2cosψ2) × L Y0 = (δ1sinψ1 + δ2sinψ2) × L