JPH11237207A - Laser interferometer - Google Patents

Abstract

(57) [Problem] To realize a laser interferometer capable of easily measuring a change in posture of a moving member in two directions due to movement. SOLUTION: First and second reflecting means reflecting in opposite directions.
An angle detecting reflecting means 62 provided with 59, 60;
A beam interference combining unit 63 that divides the laser beam into laser beams emitted in the same direction and combines the laser beams reflected by the first and second reflecting means so as to interfere with each other; In a laser interferometer which includes a light receiving means 16 for receiving light and a counting means for a change in an electric signal, and counts the number of interference fringes and measures the rotation angle of the angle detecting reflecting means, the angle detecting reflecting means 62 Has a third reflecting means 61 whose arrangement direction is perpendicular to the first and second reflecting means, and the beam interference synthesizing unit emits the two laser beams to a set of the first and second reflecting means or the first and second reflecting means. It is switchable to be reflected by the third set of reflection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reflecting two split laser beams on two reflecting mirrors (corner cubes) attached to a measurement object, causing the two returned laser beams to interfere with each other, The present invention relates to a laser interferometer that measures the rotation angle by counting the number of interference fringes that change with rotation, and in particular, to measure pitch and yaw, which are two rotation components about two directions perpendicular to the direction of a laser beam. The present invention relates to a laser interferometer that can easily perform the above.

[0002]

2. Description of the Related Art Laser interferometers are widely used to measure the amount of movement of a moving member in a moving mechanism, and a laser interferometer for such an application is generally called a laser length measuring device. FIG. 1 is a diagram showing a configuration of a beam interference combining unit of a laser interferometer. The laser beam 10 is He-N
This is a laser beam with good coherence (long interference distance) output from an e-laser or the like, which is directly incident from a laser light source, or a separation type laser interference described in Japanese Utility Model Application No. 62-52869. In some cases, the light is transmitted from a laser light source via an optical fiber, as in a meter. The laser beam 10 incident on the beam interference synthesizing unit is split into two laser beams by a polarization beam splitter 11. At this time, the optical axis of the polarization beam splitter 11 is adjusted to be at 45 ° with respect to the polarization plane of the incident laser light. In this case, the laser beam transmitted through the polarizing beam splitter 11 is P
The polarization and the laser light reflected by the polarization beam splitter 11 are called S-polarized light, and the polarization directions are orthogonal to each other. One of the laser beams (P-polarized light) is incident on the corner cube 13 arranged on the stage, where it is reflected in the opposite direction and is incident on the polarization beam splitter 11 again. The other laser beam (S-polarized light) enters the reference corner cube 12 provided in the beam interference synthesizing unit, where it is reflected in the opposite direction and again enters the polarizing beam splitter 11. Polarization beam splitter 1 from corner cube 13
1 is transmitted, and the laser beam incident on the polarizing beam splitter 11 from the reference corner cube 12 is reflected.
After passing through the polarizing plate 14, the light enters the photodetector 15. These two laser beams interfere with each other and produce interference fringes. The intensity of the interference fringes is greatest when the optical path difference between the two laser beams is an integral multiple of the wavelength of the laser beam, and the optical path difference is an integral multiple of the wavelength. Is the smallest when it differs by 1/2. Therefore, when the stage moves and the corner cube 13 arranged moves, the output intensity of the photodetector 15 changes periodically. Specifically, when the corner cube 13 moves by a half wavelength, an optical path difference corresponding to the wavelength occurs in a round trip, so that the value obtained by multiplying the number of cycles in which the output intensity of the photodetector 15 changes by the half wavelength is the corner. The moving distance of the cube 13, that is, the stage.

[0003] The output signal of the photodetector 15 is amplified by an amplifier 16, compared with an intermediate level of the output signal by a comparator 17, converted into a binary signal, and counted by a counter 18. The length measurement value calculation unit 19 calculates the moving distance from the value of the counter 18. Using the laser interferometer (laser length measuring device) as described above, the movement amount of the precision movement mechanism can be measured very accurately, and is used for controlling the movement amount and inspecting the movement mechanism. For example, for NC machine tools, test items and test methods relating to accuracy are defined in standards such as ISO 230-2 and JIS-B-6201-1990. The items specified here are a movement amount error in each movement axis direction, backlash, yawing, and the like. In the test method of the movement amount error in each movement axis direction, the movement is performed by a predetermined amount for each movement axis direction. A method is defined in which after the operation is performed, the operation of returning in the same direction in the reverse direction is repeated by a predetermined amount, and the maximum value or the mean square value of the error at each moving point is calculated. For measurement of the test items as described above, a normal contact type gauge, magnetic scale, or the like is used, but a laser length measuring device is most commonly used.

The present applicant has filed Japanese Patent Application No. 8-56082,
When measuring the movement accuracy of each direction of NC machine tool,
A laser measuring device in which the direction of an axis to be measured can be easily switched is disclosed. FIG. 2 is a view showing an example of measuring the movement accuracy in each axial direction of the NC machine tool using the laser length measuring device disclosed in Japanese Patent Application No. 8-56082. Machine tool 91
A processing tool part 92 for holding and driving the processing tool;
A stage 93 on which a workpiece is placed, and N for controlling them
A C controller 94 is provided. The processing tool unit 92 can move in the vertical direction (Z-axis direction), and the mounting table 93 can move in two mutually perpendicular directions in a plane perpendicular to the Z-axis direction. Controlled.
In this example, the beam interference synthesizing unit 20 is mounted on the tool shaft 92 using the separation type laser interferometer described in Japanese Utility Model Application No. 62-52869, and the beam interference synthesizing unit 20, the laser light source 21 and the signal processing unit 24 are connected by optical fibers 22 and 23. The beam interference synthesizing unit 20 changes the direction in which the measurement laser beam is emitted by moving a reflecting means such as a prism, in X, Y, and Z directions.
The switching can be performed in the axial direction, and this switching can be performed from the controller 25 via the switching drive unit 27 and the cable 28.

When a measurement is performed, an X-axis corner cube 132 is placed on a portion of the stage 93 that moves in the X-axis direction.
The Y-axis corner cube 13 is provided in the portion that moves in the Y-axis direction.
2, the Z-axis corner cube 131 is fixed to the portion that moves in the Z-axis direction, and the beam interference combining unit 20 is switched so that the measurement laser beam is emitted in the axial direction to be measured first, and is emitted. The measurement laser beam is set so as to be input to the corresponding corner cube.
The measurement is performed in that state, and when the measurement is completed, the same operation is sequentially performed on the other axes.

As described above, by using the laser length measuring device disclosed in Japanese Patent Application No. 8-56082, the movement accuracy in three movement axis directions can be changed without changing the mounting direction of the beam interference synthesizing unit 20. It becomes possible to measure continuously. On the other hand, ISO 230-2 and JIS-B-6201
In the standards such as -1990, it is necessary to measure not only the movement amount error in each movement axis direction but also the attitude change due to the movement of the moving member called pitch or yawing.

[0007] The laser interferometer can measure the amount of rotation about an axis perpendicular to the emission direction of the laser beam as the center of rotation. FIG. 3 is a diagram illustrating the principle of measuring the amount of rotation with a laser interferometer. The laser beam emitted from the laser light source 21 is transmitted through the optical fiber 22, and the laser beam emitted from the end face of the optical fiber 22 is converted into a parallel beam by the lens 31, and the rotation angle is detected by a polarization beam splitter (hereinafter simply referred to as “polarization beam splitter”). This is called a beam splitter.) 3
4 is incident. The parallel laser beam is split into two beams by a beam splitter 34, one of which is emitted as it is, and the other is reflected by a reflecting surface to be converted into a beam parallel to one of the beams, and then emitted. The angle measuring reflection unit 37 is arranged so that the incident surface is the same plane.
There are two corner cubes 35 and 36, and two laser beams from the beam splitter 34 are incident on the two corner cubes 35 and 36 and reflected in opposite directions. The two reflected laser beams are incident on a beam splitter 34 and are combined, and after passing through a polarizing plate 33, a lens 32
Is converged on the end face of the optical fiber 23, and is converted into an electric signal by the light receiving signal processing unit 24 via the optical fiber 23 and processed. That is, interference fringes corresponding to the optical path difference between the two laser beams are detected.

When the angle measuring reflection unit 37 rotates in the plane of the drawing, the optical path difference between the two laser beams changes,
A change in interference fringes is observed. Specifically, twice the length obtained by multiplying the arrangement distance of the two corner cubes 35 and 36 by the rotation angle is a change in the optical path difference, and if the amount of change in interference fringes is detected, the reflection unit for angle measurement is used. 37 rotation angles can be measured.

There are two directional components when detecting a change in posture of a moving member due to movement. In FIG. 3, the rotation component in the paper plane, that is, the rotation with the axis perpendicular to the paper plane as the rotation axis can be measured, but the rotation with the rotation axis perpendicular to the laser beam direction and in the paper plane cannot be measured, In order to measure the rotation, the corner cube 36 must be placed on the corner cube 35, and the laser beams emitted from the beam splitter 34 must be separated in the vertical direction. For example, when measuring a posture change in the movement in the X-axis direction in the three-dimensional movement mechanism, when measuring a rotation component about the rotation axis of the Y-axis, two laser beams emitted from the beam interference synthesizing unit are It is displaced in the Z-axis direction, and it is necessary to dispose two corner cubes in the Z-axis direction so that two laser beams are incident. When measuring a rotation component about the rotation axis of the Z-axis, The two laser beams emitted from the beam interference synthesizing unit are shifted in the Y-axis direction, and it is necessary to dispose two corner cubes in the Y-axis direction so that the two laser beams enter.

[0010]

Conventionally, for a reflection unit for angle measurement, three corner cubes are arranged so that the plane of incidence is the same plane, and the second and second corner cubes are arranged with respect to the first corner cube. It is known that corner cubes 3 are arranged so that the arrangement directions are perpendicular to each other. By using such an angle measurement reflection unit,
Even when detecting a change in the posture of the moving member in two directions due to the movement, there is no need to change the arrangement of the corner cubes.
However, the arrangement direction of the two parallel laser beams emitted from the beam interference synthesizing unit is fixed, and the mounting of the beam interference synthesizing unit is changed in order to detect a change in the attitude of the moving member in two directions due to the movement. Thus, it was necessary to change the arrangement direction of the two parallel laser beams. Therefore, after the measurement of the attitude change in one direction is completed, it is necessary to change the attachment of the beam interference synthesizing unit and measure the attitude change in the other direction, which poses a problem that the operation is complicated. Was.

An object of the present invention is to solve such a problem, and an object of the present invention is to realize a laser interferometer capable of easily measuring a change in a posture of a moving member in two directions due to the movement.

[0012]

In order to achieve the above object, a laser interferometer of the present invention comprises three corner cubes having the same plane of incidence and the first corner cube. The beam interference synthesizing unit uses the angle detecting reflecting means arranged so that the arrangement directions of the second and third corner cubes are perpendicular to each other. It can be switched in accordance with the detecting reflection means.

That is, the laser interferometer of the present invention has an incident surface in the same plane, and includes first and second reflecting means for reflecting light incident on the incident surface in opposite directions. , A laser light source, and a laser beam from the laser light source are divided into first and second laser beams emitted in the same direction, and the first and second laser beams are reflected by the first and second reflecting means of the angle detecting reflecting means, respectively. A beam interference combining unit for combining the first and second laser beams returning so as to interfere with each other, and receiving interference light of the first and second laser beams combined by the beam interference combining unit to form interference fringes. Light receiving means for generating a corresponding electric signal; and counting means for counting the number of cycles of change of the electric signal output from the light receiving means, and counting the number of interference fringes changing with the rotation of the angle detecting reflecting means. Angle detection In a laser interferometer for measuring a rotation angle of an object to which a reflecting means is attached, the reflecting means for angle detection has an incident surface in the same plane as the incident surfaces of the first and second reflecting means. A third reflector for reflecting the incident light in a reverse direction, wherein the arrangement direction of the third reflector and the first reflector is perpendicular to the arrangement direction of the first and second reflectors; The interference synthesizing unit reflects the first and second laser beams emitted by the first and second sets of angle detecting reflecting means, respectively, and the first and second sets of angle detecting reflecting means. It is characterized in that it can be switched between a state in which each is reflected by the third set of reflection means.

According to the laser interferometer of the present invention, it is possible to switch so as to be able to measure the attitude change in two directions due to the movement. Therefore, when measuring the attitude change in two directions, the mounting direction of the beam interference synthesizing unit is changed. There is no need to perform the measurement, and the measurement operation is easy and automation is possible. The switching of the beam interference synthesizing unit may be performed manually or automatically according to an electric signal.

The state switching mechanism in the beam interference combining unit as described above provides two sets of a combination of a beam splitter having different reflection directions and a reflection means such as a prism so that one of them is arranged in the optical path of the laser beam. Alternatively, a single beam splitter is provided, and two reflecting means for emitting one of the divided laser beams from different positions are provided, and switching is performed so that one of the divided laser beams is disposed in the optical path of the laser beam.

Further, in order to switch so that the moving distance can also be measured, the beam interference synthesizing unit emits only one of the divided laser beams and reflects the other laser beam in the opposite direction to serve as a reference laser beam, thereby detecting an angle. Any one of the reflecting means may be used as the moving reflecting means. In this case, all of the movement accuracy and the posture change accompanying the movement can be measured.

Further, there is provided an emission direction switching means for switching the emission directions of two laser beams emitted when measuring a posture change or one laser beam emitted when measuring a moving distance to three directions different from each other by 90 °. It is also possible to provide the above-described measurement of the moving distance and the posture change in all three axial directions.

[0018]

FIG. 4 is a perspective view showing the structure of a beam interference synthesizing unit in the first embodiment, and FIG. 5 is a view showing the beam interference synthesizing unit and the angle detecting reflection unit in the first embodiment. FIG. 3 is a diagram showing a configuration of an optical system of FIG. As shown in FIG. 5 (1), the laser interferometer of the first embodiment is a separation type laser interferometer described in Japanese Utility Model Application No. 62-52869. It is provided at the place. Further, as shown in FIG. 5 (2), the reflection unit 62 for angle detection has three corner cubes 59 to 61 arranged as shown. The three corner cubes 59 to 61 are arranged such that the incident surfaces are on the same plane, and furthermore, are arranged such that the arrangement direction of the corner cubes 59 and 60 and the arrangement direction of the corner cubes 59 and 61 are 90 °. ing. Therefore, the two laser beams emitted from the beam interference synthesizing unit are switched between a state where they are incident on the corner cubes 59 and 60 and a state where they are incident on the corner cubes 59 and 61, so that the incident laser beam , Ie, a change in the attitude of the angle detecting reflection unit 62 can be measured.

The first switchable moving plate 47 includes the feed screw 4
8, a parallel movement is performed by a feed mechanism including a shaft 49, a side member 50, and a motor 51. On the first switching moving plate 47, a first set of a first beam splitter 41 and a reflecting prism 42, a second set of a second beam splitter 43 and a reflecting prism 44, and a first beam splitter A third set of 41 and a reference corner cube 46 is provided. FIGS. 4 and 5 (1) show a state in which the first set is used. The first beam splitter 41 and the reflecting prism 42 form the same optical system as shown in FIG. 1 beam splitter 41 and reflection prism 42
The first and second laser beams emitted from are incident on corner cubes 59 and 60 and are reflected in opposite directions. With such a configuration, similarly to FIG. 3, the rotation of the angle detection reflection unit 62 about the axis perpendicular to the paper surface as the rotation axis can be measured.

The first switchable moving plate 47 is moved to
Is arranged in the optical path, the second beam splitter 43 and the reflecting prism 44
, Two parallel laser beams deviated in the direction perpendicular to the plane of the paper are emitted, enter the corner cubes 59 and 61, and are reflected in opposite directions. With such a configuration, the rotation about the axis perpendicular to the incident laser beam as the rotation axis can be measured in the paper of the angle detection reflection unit 62.

When the first switching moving plate 47 is further moved so that the third beam splitter 45 is disposed in the optical path, one of the laser beams split by the fifth beam splitter 43 is turned into a corner cube 59. And is reflected in the opposite direction, and the other laser beam is incident on the reference corner cube 46 and is reflected in the opposite direction. With such a configuration, the configuration shown in FIG. 1 is realized, and the moving distance of the angle detection reflection unit 62 in the direction along the laser beam can be measured.

The second switching plate 54 is provided with a feed screw 5
5. The parallel movement is performed by the feed mechanism including the shaft 56, the side member 57, and the motor 58. On the second switching moving plate 54, a first deflecting prism 52 and a second deflecting prism 53 are provided. (1) of FIGS. 4 and 5
In the state shown in (1), the laser beam emitted from the beam interference synthesizing unit is
Irrespective of the three states in which is moved, the light is emitted to the right on the paper in FIG. On the other hand, the second switching moving plate 54 is moved so that the first deflecting prism 52
Is placed in the optical path, the laser beam emitted from the beam interference synthesizing unit is emitted downward in a direction perpendicular to the plane of FIG. 5A, and the second deflecting prism 53 is placed in the optical path. In this state, the laser beam emitted from the beam interference synthesizing unit is emitted downward on the plane of FIG. 5A. In this way, the emitted laser beam is switched so as to be emitted in three directions of X, Y, and Z.

FIG. 6 shows the movement accuracy of the moving mechanism of the machine tool in the three axes of X, Y, and Z using the laser interferometer of the first embodiment, and changes in the attitude in two directions (pitch yawing). FIG. 7 is a diagram showing an arrangement when measuring ()). As shown in the figure, the beam interference synthesizing unit 63 is attached to the tool shaft 92, and three angle detecting reflection units 62X, 62Y and 62Z are arranged on the stage 93.

When measuring the accuracy of movement in the Z-axis direction, the beam interference synthesizing unit 63 switches the first deflecting prism 52 so that the laser beam is emitted in the Z-axis direction by disposing the first deflecting prism 52 in the optical path. Then, while switching the state of using the first and second sets, the angle detection reflection unit 62Z is set so that the two sets of laser beams are respectively incident on the three corner cubes of the angle detection reflection unit 62Z.
Is adjusted, and the coordinates of the moving mechanism at that time are stored.
Similarly, after switching so that the laser beam is emitted in the X-axis direction from the beam interference synthesizing unit 63, the tool axis is lowered, and the angle detection is performed so as to enter the three corner cubes of the angle detection reflection unit 62X. The position of the reflection unit 62X is adjusted, and the coordinates of the moving mechanism at that time are stored. This is also performed in the Y-axis direction. When measuring the movement accuracy in the X-axis and Y-axis directions, the position of the angle detection reflection units 62X and 62Y is increased using a table if necessary, and the laser emitted from the beam interference synthesis unit 63 is used. The beams are reflected by the angle detecting reflection units 62X and 62X.
Make it easy to input in 2Y.

After the above setting is completed, the movement accuracy and the change in posture in each movement axis direction are automatically measured by program control. Normally, measurement requires a considerable amount of time to perform the same item a plurality of times and perform statistical processing. However, if the above settings are made, the subsequent operation can be performed automatically, so that the work efficiency is greatly improved. In the first embodiment, by switching the set of the beam splitter and the reflecting prism, the emission positions of the two laser beams can be switched to be shifted in different directions, and further by switching to the set of the beam splitter and the corner cube. Movement distance can be measured. However, the beam splitter is more expensive than the reflection prism and the like, and the configuration of the first embodiment has a problem that the cost is increased because three beam splitters are used. Therefore, in the second embodiment, a beam interference combining unit having the same function as the first embodiment is realized using one beam splitter.

FIG. 7 is a diagram showing a configuration of a beam interference combining unit of the laser interferometer of the second embodiment. As shown in (1) of FIG. 7, with respect to the beam splitter 41,
The reflecting prisms 42, 70, 71 and the corner cube 72 are arranged, and the reflecting prisms 42, 70, 7
1 and the corner cube 72 are configured to be movable in the direction of the arrow by a moving mechanism (not shown). In the illustrated state, one of the laser beams split by the beam splitter 41 is reflected by the reflecting prism 42 and emitted in parallel with the other laser beam. The emission positions are shifted in the horizontal direction, and the state shown in FIG. Next, the reflecting prism 70 is connected to the reflecting prism 42 shown in FIG.
Is moved to the position, the reflecting prism 71 moves to a position above the beam splitter 41. In this state, one of the laser beams split by the beam splitter 41 is reflected by the reflecting prisms 70 and 71, and is emitted from the reflecting prism 71 in parallel with the other laser beam. The emission position is shifted vertically. The optical path in this state is shown in FIG. Next, when the corner cube 72 is moved to the position of the illustrated reflecting prism 42, the state shown in FIG. 1 is realized, and the moving distance can be measured.

[0027]

As described above, according to the present invention,
A laser interferometer capable of easily measuring a change in the posture of a moving member in two directions due to movement is realized, and a movement accuracy of the moving mechanism and a change in posture due to the movement can be continuously measured without requiring human intervention on the way. . Further, in the case of a moving mechanism having a plurality of moving axes, it is possible to continuously and automatically measure all the measurement items by further adding a mechanism for switching the emission direction of the laser beam. . Therefore, the cost required for the measurement can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a beam interference combining unit of a conventional laser interferometer.

FIG. 2 is a diagram showing a configuration of an automatic measurement system for a machine tool according to a conventional example.

FIG. 3 is a diagram illustrating a method of measuring a rotation angle by a laser interferometer.

FIG. 4 is a perspective view illustrating a configuration of a beam interference combining unit in the laser interferometer according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of an optical system including a beam interference combining unit and an angle detecting reflection unit according to the first embodiment.

FIG. 6 is a diagram illustrating an example of an arrangement for measuring a movement error and a change in posture of a machine tool in a movement axis direction using a laser interferometer of the present invention.

FIG. 7 is a diagram illustrating a configuration of a beam interference combining unit in a laser interferometer according to a second embodiment of the present invention.

[Explanation of symbols]

21 laser light source 20, 63 beam interference combining unit 16 signal processing unit 41, 43, 45 beam splitter 42, 44, 52, 53, 70, 71 reflecting prism 46, 59-61 corner cube 62, 62X , 62Y, 62Z ... Reflection unit for angle detection

Claims (6)

[Claims] 1. An angle detecting reflecting means (62) having an incident surface in the same plane and comprising first and second reflecting means (59, 60) for reflecting light incident on the incident surface in opposite directions. )
A laser light source (21); and a laser beam from the laser light source (21) is divided into first and second laser beams emitted in the same direction. A beam interference synthesizing unit (63) for synthesizing the first and second laser beams reflected and returned by the second reflecting means so as to interfere with each other; and the first interference beam synthesized by the beam interference synthesizing unit. And the second
Light receiving means (16) for receiving the interference light of the laser beam and generating an electric signal according to the interference fringe; and counting means for counting the number of cycles of the change of the electric signal output from the light receiving means (16). A laser interferometer that counts the number of the interference fringes that changes with the rotation of the angle detection reflection means and measures the rotation angle of the object to which the angle detection reflection means is attached; The reflecting means has an incident surface in the same plane as the incident surface of the first and second reflecting means (59, 60),
A third reflecting means (61) for reflecting light incident on the incident surface in a reverse direction, wherein the arrangement direction of the third reflecting means (61) and the first reflecting means (59) is the first direction; The beam interference synthesizing unit forms the first and second laser beams emitted from the first and second laser beams at a right angle with the arrangement direction of the second and third reflecting means (59, 60). And a state where the light is reflected by the set of the first and third reflecting means (59, 61) of the angle detecting reflecting means. A laser interferometer that is switchable between the two. 2. The laser interferometer according to claim 1, wherein the beam interference combining unit divides a laser beam from the laser light source (21) into the first and second laser beams. A first beam splitter (41) for combining the first and second laser beams reflected back and returning so as to interfere with each other;
And at least one of the first and second laser beams so that the first and second laser beams are emitted in the same direction and enter the first and second reflecting means (59, 60). First emission direction adjusting means (42) for changing the emission direction
A first beam interference combining unit having: a laser beam source from the laser light source (21); and a first and second laser beams. The first and second laser beams are reflected in opposite directions and returned. Beam splitter (43) for combining the laser beam and the second laser beam so as to interfere with each other
And at least one of the first and second laser beams so that the first and second laser beams are emitted in the same direction and enter the first and third reflecting means (59, 61). Second emission direction adjusting means for changing the emission direction (44)
A second beam interference synthesizing unit having: and a switch for switching a laser beam from the laser light source (21) to enter one of the first beam interference synthesizing unit and the second beam interference synthesizing unit. A laser interferometer comprising means (47, 48, 49, 50, 51). 3. The laser interferometer according to claim 1, wherein the beam interference synthesizing unit divides a laser beam from the laser light source into the first and second laser beams. A first beam splitter (41) for combining the first and second laser beams reflected back and returning so as to interfere with each other;
And the first and second laser beams are emitted in the same direction,
First emission direction adjusting means (42) for changing the emission direction of at least one of the first and second laser beams so as to be incident on the first and second reflection means (59, 60); The first and second laser beams are emitted in the same direction,
Second emission direction adjusting means (70, 7) for changing the emission direction of at least one of the first and second laser beams so as to be incident on the first and third reflection means (59, 61).
1) and switching means for switching so that the laser beam from the laser light source (21) enters one of the first emission direction adjustment means (42) and the emission direction adjustment means (70, 71). Equipped laser interferometer. 4. The laser interferometer according to claim 1, wherein the beam interference synthesizing unit emits only the first laser beam and emits the second laser beam. The reference laser beam is reflected in the reverse direction to make the reference laser beam interfere with the first laser beam reflected by any of the first to third reflecting means (59, 60, 61). It is possible to switch to a combining state, and it is also possible to count the number of interference fringes changing with the movement of the angle detecting reflecting means and measure the moving distance of the object to which the angle detecting reflecting means is attached. Laser interferometer. 5. The laser interferometer according to claim 4, wherein the beam interference synthesizing unit reflects the second laser beam in a reverse direction to produce a reference laser beam. A laser interferometer comprising: 6. The laser interferometer according to claim 1, wherein the first and second laser beams or the first laser beam emitted from the beam interference synthesizing unit are provided. Direction switching means (52, 53, 54, 55, 56, 5) for switching the direction of emission of light into three directions different from each other by 90 °.
7, 58).