JP7413646B2 - Measuring device and measuring system - Google Patents

Description

The present invention relates to a measuring device and a measuring system for measuring the positioning accuracy and straightness of a machine in three axial directions.

BACKGROUND ART Various machines such as NC (Numerically Controlled) machine tools, optical machines, and measuring machines are equipped with various movement mechanisms that move in three axial directions: an X direction, a Y direction, and a Z direction. In such various machines, it is important to ensure accuracy in three axial directions.

For example, the measuring device described in Patent Document 1 uses an optical interference unit to perform processing while relatively moving an optical interference unit provided in a processing tool section of an NC machine tool and a measurement reflection unit arranged in three axial directions. By individually measuring the distance between the tool part and each measuring reflection unit, the positioning accuracy of the NC machine tool in the three-axis directions is measured.

Further, the measuring device described in Patent Document 2 emits a laser beam to a corner cube prism of the linearly moving body while relatively moving a linearly moving body of a machine tool and a measuring device body provided on the machine tool in one direction. By performing the following steps and detecting the laser beam retroreflected by the corner cube prism, the straightness (linear motion accuracy) of the machine tool in one direction is measured.

International Publication No. 2007/020738 Japanese Patent Application Publication No. 1-57110

By the way, in the above-mentioned various machines, it is desired to measure both the positioning accuracy in three axial directions and the straightness in three axial directions. The measuring device described in Patent Document 1 described above can measure positioning accuracy in three axial directions, but cannot measure straightness in three axial directions. Conversely, the measuring device described in Patent Document 2 described above can measure straightness in one axis direction, but cannot measure positioning accuracy and straightness in three axis directions.

Furthermore, if the measuring device of Patent Document 1 and the measuring device of Patent Document 2 are to be combined to measure the positioning accuracy and straightness of various machines in the 3-axis directions, replacement work is required to replace the two types of measuring devices. This replacement work requires a lot of time. Further, in this case, it is necessary to manually change the setup to change the measurement of straightness in each direction of the three axes, and this setup change also requires a lot of time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a measuring device and a measuring system that can efficiently measure the positioning accuracy and straightness of a machine in three axial directions.

A measuring device for achieving the object of the present invention is a measuring device that measures the positioning accuracy and straightness of a machine in three axes of X direction, Y direction, and Z direction that are perpendicular to each other. a light emitting section that emits a first laser beam and a second laser beam along one direction; a first polarization splitting element and a second polarization splitting element provided along one direction from the light emitting section; and a third polarization splitting element, a common retroreflector provided at a position facing the first polarization splitting element in the Y direction, and when mutually orthogonal linearly polarized lights are the first polarized light and the second polarized light, A polarization conversion state that converts the polarization state of the first laser beam and the second laser beam from one of the first polarization and the second polarization to the other between the first polarization separation element and the second polarization separation element, and the polarization state is maintained. a first polarization converter capable of switching between the polarization conversion state and the polarization maintenance state between the second polarization separation element and the third polarization separation element; The first polarization splitting element outputs the first polarized light of the first laser beam and the second laser beam incident from the light emitting part to the second polarization splitting element, and outputs the second polarized light to the common retroreflector. The first polarized light incident from the second polarization splitting element is emitted in the other direction in the X direction, the second polarized light reflected by the common retroreflector is emitted in the other direction, and the second polarized light splitting element outputs the first polarized light incident from one of the first polarization splitting element and the third polarization splitting element to the other of the first polarization splitting element and the third polarization splitting element, and outputs the second polarized light incident from the first polarization splitting element. The second polarized light reflected by the first external retroreflector is emitted to the first polarized light splitting element, and the second polarized light reflected by the first external retroreflector is emitted to the first polarized light splitting element. The three-polarization splitting element outputs the first polarized light incident from the second polarization splitting element to a second external retroreflector provided on the Z-direction side of the third polarization splitting element, and outputs the second polarized light to the third polarization splitting element. The first polarized light is emitted to a third external retroreflector provided on one side, reflected by the second external retroreflector, and incident on the second polarization separation element, and is emitted to the third external retroreflector. The reflected and incident second polarized light is emitted to the second polarization separation element, and the first polarization conversion section and the second polarization conversion section are connected to the first external retroreflector, the second external retroreflector, and the third external retroreflector. Emission switching is performed to switch the emission of the first laser beam and the second laser beam to the reflector.

According to this measuring device, positioning accuracy and straightness in three axial directions can be automatically measured.

In the measuring device according to another aspect of the present invention, when emitting the first laser beam and the second laser beam to the first external retroreflector, the first polarization conversion section switches to the polarization conversion state and the second When the polarization conversion section switches to the polarization maintenance state and outputs the first laser beam and the second laser beam to the second external retroreflector, the first polarization conversion section and the second polarization conversion section switch to the polarization maintenance state. When switching and emitting the first laser beam and the second laser beam to the third external retroreflector, the first polarization converter switches to the polarization maintaining state and the second polarization converter switches to the polarization converting state. Thereby, each external retroreflector can be selectively irradiated with the first laser beam and the second laser beam.

In the measuring device according to another aspect of the present invention, the first polarization conversion section includes a first common polarization conversion element that converts one of the first polarization and the second polarization into the other, and a first common polarization conversion element that converts one of the first polarization and the second polarization into the other; A conversion element is inserted between the first polarization separation element and the second polarization separation element, and the first common polarization conversion element is retracted from between the first polarization separation element and the second polarization separation element in the polarization maintenance state. and a first insertion/removal section. Thereby, each external retroreflector can be selectively irradiated with the first laser beam and the second laser beam.

In the measuring device according to another aspect of the present invention, the second polarization conversion section includes a second common polarization conversion element that converts one of the first polarization and the second polarization into the other, and a second common polarization conversion element that converts one of the first polarization and the second polarization into the other; A conversion element is inserted between the second polarization separation element and the third polarization separation element, and the second common polarization conversion element is retracted from between the second polarization separation element and the third polarization separation element in the polarization maintenance state. and a second insertion/removal section. Thereby, each external retroreflector can be selectively irradiated with the first laser beam and the second laser beam.

In the measurement device according to another aspect of the present invention, the device is provided on the optical path of the second laser beam between the second polarization separation element and the first external retroreflector, and and a first retroreflector provided at a position opposite to the first polarization conversion element with respect to the second polarization separation element in the Y direction; a first retroreflector that reflects a second laser beam incident from the element to a second polarization separation element, and the second polarization separation element receives a second laser beam incident from one of the first external retroreflector and the first retroreflector. The first polarized light of the second laser beam is emitted to the other of the first external retroreflector and the first retroreflector. Thereby, the displacement of the first external retroreflector in the XZ direction can be detected in a magnified manner.

In the measurement device according to another aspect of the present invention, the device is provided on the optical path of the second laser beam between the third polarization separation element and the second external retroreflector, and a second retroreflector provided at a position opposite to the second polarization conversion element with respect to the third polarization separation element in the Z direction; a second retroreflector that reflects the second laser beam incident from the element to the third polarization separation element, and the third polarization separation element receives the second laser beam incident from one of the second external retroreflector and the second retroreflector. The second polarized light of the second laser beam is emitted to the other of the second external retroreflector and the second retroreflector. Thereby, the displacement of the second external retroreflector in the X and Y directions can be magnified and detected.

In the measurement device according to another aspect of the present invention, a fourth polarization separation element is provided between the third polarization separation element and the third external retroreflector, and the fourth polarization separation element is provided between the third polarization separation element and the third external retroreflector. a fourth polarization separation element that outputs the second polarized light incident from one of the retroreflectors to the other of the third polarization separation element and the third external retroreflector; and the fourth polarization separation element and the third external retroreflector. a third polarization conversion element that is provided on the optical path of the second laser beam between the two and converts one of the first polarized light and the second polarized light into the other; and a fourth polarization separation element that is provided at a position facing the Z direction. a third retroreflector that reflects the second laser beam incident from the fourth polarization separation element to the fourth polarization separation element, the fourth polarization separation element, The first polarized light of the second laser beam incident from one of the third external retroreflector and the third retroreflector is emitted to the other of the third external retroreflector and the third retroreflector. Thereby, the displacement of the third external retroreflector in the YZ direction can be detected in a magnified manner.

In the measuring device according to another aspect of the present invention, the first polarization separation element selectively reflects light at the first external retroreflector, the second external retroreflector, and the third external retroreflector according to output switching. The first polarized light reflected by the common retroreflector and the second polarized light reflected by the common retroreflector are emitted in the other direction from different positions for each of the first laser beam and the second laser beam. Positioning accuracy and straightness can be measured simultaneously in each of the three axial directions.

In the measuring device according to another aspect of the present invention, a first detection unit that detects an interference signal between the first polarized light and the second polarized light of the first laser beam emitted from the first polarization separation element in the other direction; a fifth polarization splitting element that polarizes and outputs the first polarized light and the second polarized light of the second laser beam emitted from the first polarization splitting element in the other direction; A second detection section that detects polarized light; and a third detection section that detects the second polarized light emitted from the fifth polarization separation element; Detection of the signal, detection of the first polarized light by the second detection section, and detection of the second polarized light by the third detection section are performed. Thereby, positioning accuracy and straightness in three axial directions can be automatically measured.

A measuring system for achieving the object of the present invention detects the positioning accuracy in each of the three axial directions based on the above-mentioned measuring device and the detection result of the first detection unit detecting the interference signal in each of the three axial directions. Straightness is detected for each of the three axial directions based on the positioning accuracy detection section, the detection result of the first polarized light for each of the three axial directions by the second detection section, and the detection result of the second polarized light by the third detection section. A straightness detection section.

The present invention can efficiently measure the positioning accuracy and straightness of a machine in three axial directions.

FIG. 2 is a schematic diagram of the measurement system. FIG. 3 is a perspective view of an X external retroreflector, a Y external retroreflector, a Z external retroreflector, and a measuring device. FIG. 1 is a schematic diagram showing the configuration of a measuring device. FIG. 6 is a ray diagram of the first laser beam in simultaneous measurement in the X direction. It is a front view of the X external retroreflector seen from the +X direction side. FIG. 6 is a ray diagram of the second laser beam during simultaneous measurement in the X direction. FIG. 6 is a ray diagram of the first laser beam during simultaneous measurement in the Y direction. FIG. 6 is a ray diagram of the second laser beam during simultaneous measurement in the Y direction. FIG. 6 is a ray diagram of the first laser beam during simultaneous measurement in the Z direction. FIG. 6 is a ray diagram of the second laser beam during simultaneous measurement in the Z direction. FIG. 2 is a schematic diagram showing the configuration of a receiver section. FIG. 3 is a model diagram for explaining displacement detection of an X external retroreflector. 2 is a flowchart showing a process flow of simultaneous measurement of positioning accuracy and straightness in three axial directions by the measurement system.

[Overall configuration of machine tool and measurement system]
FIG. 1 is a schematic diagram of a measurement system 10 comprising a measurement device 14 according to the invention. As shown in FIG. 1, the measurement system 10 automatically measures the positioning accuracy and straightness of the machine tool 91 in three mutually orthogonal axes directions (X direction, Y direction, and Z direction). Note that in this embodiment, the X direction and the Y direction are horizontal directions, and the Z direction is the vertical direction (height direction).

The machine tool 91 includes a processing tool section 92 that holds and drives a processing tool, a mounting table 93 on which a workpiece is placed, and an NC controller 97.

The processing tool section 92 is movable in the Z direction, and the mounting table 93 is movable in the X and Y directions. Note that as long as one of the processing tool section 92 and the mounting table 93 is movable relative to the other in the three-axis directions, there are no particular limitations on whether or not the processing tool section 92 and the mounting table 93 move or not and in what direction they move. The mounting table 93 also includes an X external retroreflector 171, a Y external retroreflector 172 (see FIG. 2), and a Z external retroreflector, which are used to measure the positioning accuracy and straightness of the machine tool 91 in three axes. The container 173 is set.

The NC controller 97 controls movement of the processing tool section 92 and the mounting table 93 under the control of the computer 31. This NC controller 97 instructs each moving mechanism (not shown) of the processing tool section 92 and the mounting table 93 to move by a predetermined movement amount in each direction. Each moving mechanism moves the processing tool section 92 in the Z direction and the mounting table 93 in the XY directions by driving each moving mechanism based on the NC controller 97.

The measurement system 10 measures the amount of actual movement of one of the processing tool section 92 and the mounting table 93 in three axial directions, in response to instructions from the NC controller 97 . Thereby, the measurement system 10 measures the error between the instruction from the NC controller 97 and the operation of the moving mechanism in each of the three axial directions, and measures the positioning accuracy of the machine tool 91 in the three axial directions.

Furthermore, when measuring the positioning accuracy in the three-axis directions, the measurement system 10 measures the displacement of the machine tool 91 in the three-axis directions by measuring the displacement in the vertical direction with respect to the movement direction of each of the processing tool section 92 and the mounting table 93. Measure the straightness of. That is, the measurement system 10 sequentially performs simultaneous measurement of positioning accuracy and straightness in the X direction, simultaneous measurement of positioning accuracy and straightness in the Y direction, and simultaneous measurement of positioning accuracy and straightness in the Z direction.

The measurement system 10 shares a computer 31 with a machine tool 91 and includes a laser light source 11, a measurement device 14, a straightness signal processing unit 15, a positioning accuracy signal processing unit 16, and a switching controller 32.

The computer 31 is connected to the laser light source 11, the straightness signal processing unit 15, the positioning accuracy signal processing unit 16, the switching controller 32, and the NC controller 97 via a data communication cable 33. Control signals and data are transmitted and received between the two. The computer 31 includes an arithmetic circuit including various processors, memories, and the like. Various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), and programmable logic devices [for example, SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays)]. Note that various functions of the computer 31 may be realized by one processor, or may be realized by multiple processors of the same type or different types.

The processor of the computer 31 executes a measurement program stored in a storage section (not shown) to control the laser light source 11, the straightness signal processing unit 15, the positioning accuracy signal processing unit 16, the switching controller 32, and the NC controller. Control 97.

Laser light source 11 is connected to measurement device 14 via optical fiber 124. The laser light source 11 emits a first laser beam L1 for measuring the positioning accuracy of the machine tool 91 and a second laser beam L2 for measuring the straightness to the measuring device 14, as shown in FIG. 3, which will be described later. As the first laser beam L1 and the second laser beam L2, a laser beam having a long coherence distance, such as a He--Ne laser, is used, for example. Note that in this embodiment, the first laser beam L1 and the second laser beam L2 are emitted from the single laser light source 11, but the laser light source 11 that emits the first laser beam L1 and the second laser beam L2 are emitted from the single laser light source 11. A laser light source 11 may be provided separately.

The straightness signal processing unit 15 is connected to the measuring device 14 via an electric cable 35. The straightness signal processing unit 15 detects the straightness of the machine tool 91 in three axial directions based on signals input from the measuring device 14, as will be described in detail later.

The positioning accuracy signal processing unit 16 is connected to the measuring device 14 via an optical fiber 122. The positioning accuracy signal processing unit 16 detects the positioning accuracy of the machine tool 91 in three axial directions based on the signal input from the measuring device 14, which will be described in detail later.

The switching controller 32 is connected to the measuring device 14 via an electric cable 35. The switching controller 32 controls a first polarization conversion section 121 and a second polarization conversion section 123 in the measuring device 14 shown in FIG. 3, which will be described later, under the control of the computer 31.

FIG. 2 is a perspective view of the X external retroreflector 171, the Y external retroreflector 172, the Z external retroreflector 173, and the measuring device 14. As shown in FIG. 2, an 2 (corresponding to external retroreflector) is a retroreflector such as a corner cube prism (the same applies to various other retroreflectors described later), and is set on the mounting table 93.

The X external retroreflector 171 is used to measure the positioning accuracy of the machine tool 91 in the X direction, that is, the positioning accuracy of the mounting table 93 in the X direction. Further, the X external retroreflector 171 is used to measure the straightness of the machine tool 91 in the X direction, that is, the displacement in the Y and Z directions when the mounting table 93 is moved in the X direction.

The Y external retroreflector 172 is used to measure the positioning accuracy of the machine tool 91 in the Y direction, that is, the positioning accuracy of the mounting table 93 in the Y direction. Further, the Y external retroreflector 172 is used to measure the straightness of the machine tool 91 in the Y direction, that is, the displacement in the X and Z directions when the mounting table 93 is moved in the Y direction.

The Z external retroreflector 173 is used to measure the positioning accuracy of the machine tool 91 in the Z direction, that is, the positioning accuracy of the processing tool section 92 in the Z direction. Further, the Z external retroreflector 173 is used to measure the straightness of the machine tool 91 in the Z direction, that is, the displacement in the X and Y directions when the processing tool section 92 is moved in the Z direction.

Note that the positions of the X external retroreflector 171 and the Y external retroreflector 172 are adjusted by the mounting aid 174 to the height in the Z direction of the first laser beam L1 and second laser beam L2 emitted from the measuring device 14. adjusted accordingly.

[Configuration of measuring device]
FIG. 3 is a schematic diagram showing the configuration of the measuring device 14. Note that one side in the X direction is defined as the +X direction side, and the other direction opposite to this one direction side is defined as the -X direction side. Further, one direction side in the Y direction is defined as a +Y direction side and the other direction side is defined as a -Y direction side, one direction side in the Z direction is defined as a +Z direction side, and the other direction side is defined as a -Z direction side.

As shown in FIG. 3, the measuring device 14 includes a first exit aperture 11A, a second exit aperture 11B, a first polarizing beam splitter 101A, a second polarizing beam splitter 103A, a third polarizing beam splitter 105A, and a third polarizing beam splitter 105A. 4-polarized beam splitter 107A, common retroreflector 101B, retroreflectors 103B, 105B, 107B, quarter-wave plates 103C, 105C, 107C, first polarization conversion section 121, and second polarization conversion section 123. , a receiver section 127, a fifth polarizing beam splitter 125A, a correction photodetector 125B, and a measurement photodetector 125C.

The first exit port 11A and the second exit port 11B correspond to the light exit section of the present invention, and are each connected to the laser light source 11 via an optical fiber 124. Although the first exit port 11A and the second exit port 11B are shown in a simplified manner in FIG. 3, they are provided at different positions in the Y direction and the Z direction. For example, the first exit port 11A is provided at a position eccentric in the Z direction with respect to the X axis (reference axis, main axis). Further, the second exit port 11B is provided at a position eccentric in the Y direction with respect to the X axis. Note that the positions of the first exit port 11A and the second exit port 11B may be changed as appropriate.

The first emission aperture 11A emits the first laser beam L1 along the +X direction side. The second emission aperture 11B emits the second laser beam L2 along the +X direction side.

A first polarizing beam splitter 101A, a second polarizing beam splitter 103A, a third polarizing beam splitter 105A, and a fourth polarizing beam splitter are arranged along the +X direction side (X axis) from the first exit port 11A and the second exit port 11B. A beam splitter 107A is provided.

Hereinafter, among linearly polarized lights whose polarization directions are orthogonal to each other, linearly polarized light whose polarization direction is in the Y direction will be referred to as first polarized light, and linearly polarized light whose polarization direction is in the Z direction will be referred to as second polarized light. Note that the first polarized light becomes so-called P polarized light for the first polarized beam splitter 101A, the second polarized beam splitter 103A, and the fifth polarized beam splitter 125A, and is the so-called P polarized light for the third polarized beam splitter 105A and the fourth polarized beam splitter. 107A becomes so-called S-polarized light. Conversely, the second polarized light becomes so-called S-polarized light for the first polarized beam splitter 101A, the second polarized beam splitter 103A, and the fifth polarized beam splitter 125A, and is the so-called S-polarized light for the third polarized beam splitter 105A and the fourth polarized beam splitter The light becomes so-called P-polarized light for the beam splitter 107A.

The first polarization beam splitter 101A (corresponding to a first polarization separation element) transmits the first polarization of each of the laser beams L1 and L2 in the X direction and the Y direction. Further, the first polarizing beam splitter 101A converts the second polarized light of each of the laser beams L1 and L2 incident from the -X direction side (first exit port 11A and second exit port 11B side) to the -Y direction side (common retroreflection). 101B side)). Further, the first polarizing beam splitter 101A reflects (emits) the second polarized light of each laser beam L1, L2 incident from the −Y direction toward the −X direction.

The common retroreflector 101B is provided at a position facing the first polarizing beam splitter 101A in the −Y direction. This common retroreflector 101B retroreflects (emits) the second polarized light of each of the laser beams L1 and L2 incident from the +Y direction side (first polarization beam splitter 101A) toward the +Y direction side.

The second polarization beam splitter 103A (corresponding to a second polarization separation element) is provided at a position facing the Y external retroreflector 172 in the -Y direction. This second polarizing beam splitter 103A transmits the first polarized light of each of the laser beams L1 and L2 in the X direction and the Y direction. Further, the second polarizing beam splitter 103A directs the second polarized light of each of the laser beams L1 and L2 incident from the -X direction side (first polarizing beam splitter 101A side) toward the +Y direction side (Y external retroreflector 172). It reflects (emits). Furthermore, the second polarization beam splitter 103A reflects (emits) the second polarized light of each laser beam L1, L2 incident from the +Y direction side toward the −X direction side.

The retroreflector 103B (corresponding to a first retroreflector) is provided at a position facing the second polarizing beam splitter 103A in the −Y direction. This retroreflector 103B, which will be described in detail later, retroreflects (emits) the second polarized light of the second laser beam L2 incident from the +Y direction side (second polarization beam splitter 103A) to the +Y direction side (Fig. 8).

The quarter-wave plate 103C (corresponding to the first polarization conversion element) converts the light of the second laser beam L2 (first polarization, second polarization) between the second polarization beam splitter 103A and the Y external retroreflector 172. They are provided at two locations on the road and off the optical path of the first laser beam L1.

Specifically, the quarter-wave plate 103C connects the optical path of the second laser beam L2 (first polarization, second polarization) reflected from the second polarization beam splitter 103A to the Y external retroreflector 172, and the Y external It is provided on the optical path of the second laser beam L2 (first polarized light, second polarized light) that is retroreflected from the retroreflector 172 to the second polarized beam splitter 103A. As a result, the 1/4 wavelength plate 103C polarizes only the second laser beam L2 that enters the second polarizing beam splitter 103A again from the second polarizing beam splitter 103A via the Y external retroreflector 172, as will be described in detail later. The state is converted from one of the first polarized light and the second polarized light to the other (see FIG. 8, etc.). In addition, in this specification, "from one of A and B to the other" also includes "from the other of A and B".

The third polarization beam splitter 105A (corresponding to a third polarization separation element) is provided at a position facing the Z external retroreflector 173 in the -Z direction. This third polarizing beam splitter 105A transmits the second polarized light of each of the laser beams L1 and L2 in the X direction and the Z direction. Further, the third polarizing beam splitter 105A directs the first polarized light of each of the laser beams L1 and L2 incident from the -X direction side (second polarizing beam splitter 103A side) toward the +Z direction side (Z external retroreflector 173). It reflects (emits). Furthermore, the third polarization beam splitter 105A reflects (emits) the first polarized light of each of the laser beams L1 and L2 incident from the +Z direction toward the −X direction.

The retroreflector 105B (corresponding to a second retroreflector) is provided at a position facing the third polarizing beam splitter 105A in the -Z direction. This retroreflector 105B, which will be described in detail later, retroreflects (emits) the second polarized light of the second laser beam L2 incident from the +Z direction side (third polarization beam splitter 105A) toward the +Z direction side (Fig. 10).

The quarter-wave plate 105C (corresponding to the second polarization conversion element) converts the light of the second laser beam L2 (first polarization, second polarization) between the third polarization beam splitter 105A and the Z external retroreflector 173. They are provided at two locations on the road and off the optical path of the first laser beam L1.

Specifically, the quarter-wave plate 105C connects the optical path of the second laser beam L2 (first polarization, second polarization) reflected from the third polarization beam splitter 105A to the Z external retroreflector 173, and the Z external It is provided on the optical path of the second laser beam L2 (first polarization, second polarization) that is retroreflected from the retroreflector 173 to the third polarization beam splitter 105A. As a result, as will be described in detail later, the quarter-wave plate 105C polarizes only the second laser beam L2 that enters the third polarizing beam splitter 105A again from the third polarizing beam splitter 105A via the Z external retroreflector 173. The state is converted from one of the first polarization and the second polarization to the other (see FIG. 10).

The fourth polarization beam splitter 107A (corresponding to a fourth polarization separation element) is provided at a position opposite to the X external retroreflector 171 in the −X direction. This fourth polarizing beam splitter 107A transmits the second polarized light of each of the laser beams L1 and L2 in the X direction and the Z direction. Further, the fourth polarizing beam splitter 107A reflects the first polarized light of the second laser beam L2 incident from the +X direction side (X external retroreflector 171 side) toward the -Z direction side (retroreflector 107B side). (emits), and reflects (emits) the first polarized light of the second laser beam L2 incident from the −Z direction toward the +X direction.

The retroreflector 107B (corresponding to a third retroreflector) is provided at a position facing the fourth polarizing beam splitter 107A in the -Z direction. This retroreflector 107B, which will be described in detail later, retroreflects (emits) the second polarized light of the first laser beam L1 incident from the +Z direction side (fourth polarization beam splitter 107A) toward the +Z direction side (Fig. 10).

The quarter-wave plate 107C (corresponding to the third polarization conversion element) converts the light of the second laser beam L2 (first polarization, second polarization) between the fourth polarization beam splitter 107A and the X external retroreflector 171. They are provided at two locations on the road and off the optical path of the first laser beam L1.

Specifically, the quarter-wave plate 107C connects the optical path of the second laser beam L2 (first polarized light, second polarized light) emitted from the fourth polarizing beam splitter 107A to the X external retroreflector 171, and the It is provided on the optical path of the second laser beam L2 (first polarized light, second polarized light) that is retroreflected from the retroreflector 171 to the fourth polarized beam splitter 107A. As a result, as will be described in detail later, the quarter-wave plate 107C polarizes only the second laser beam L2 that enters the fourth polarizing beam splitter 107A again from the fourth polarizing beam splitter 107A via the X external retroreflector 171. The state is converted from one of the first polarization and the second polarization to the other (see FIG. 6).

The first polarization conversion unit 121 and the second polarization conversion unit 123 emit the first laser beam L1 and the second laser beam L2 to the X external retroreflector 171, the Y external retroreflector 172, and the Z external retroreflector 173. Make the switch. That is, the first polarization conversion section 121 and the second polarization conversion section 123 selectively make the first laser beam L1 and the second laser beam L2 incident on each of the external retroreflectors 171 to 173.

The first polarization converter 121 converts the polarization state of each laser beam L1, L2 from one of the first polarization and the second polarization to the other between the first polarization beam splitter 101A and the second polarization beam splitter 103A. It is possible to switch between a polarization conversion state and a polarization maintenance state in which the polarization state is maintained. The first polarization conversion section 121 includes a first half-wave plate 121A (corresponding to a first common polarization conversion element) and an actuator 121B (corresponding to a first insertion/removal section).

The actuator 121B holds the first 1/2 wavelength plate 121A in a removable manner between the first polarizing beam splitter 101A and the second polarizing beam splitter 103A. In the polarization conversion state, the actuator 121B inserts the first half-wave plate 121A between the first polarization beam splitter 101A and the second polarization beam splitter 103A. As a result, the polarization state of each of the laser beams L1 and L2 incident from one of the first polarization beam splitter 101A and the second polarization beam splitter 103A to the other is converted from one of the first polarization and the second polarization to the other.

Conversely, in the polarization maintaining state, the actuator 121B retracts the first half-wave plate 121A from between the first polarizing beam splitter 101A and the second polarizing beam splitter 103A. Thereby, the polarization state of each laser beam L1, L2 entering from one of the first polarizing beam splitter 101A and the second polarizing beam splitter 103A to the other is maintained.

The second polarization conversion unit 123 can be switched between the polarization conversion state and the polarization maintenance state described above between the second polarization beam splitter 103A and the third polarization beam splitter 105A. The second polarization conversion section 123 includes a second half-wave plate 123A (corresponding to a second common polarization conversion element) and an actuator 123B (corresponding to a second insertion/removal section).

The actuator 123B holds the second 1/2 wavelength plate 123A removably inserted between the second polarizing beam splitter 103A and the third polarizing beam splitter 105A. In the polarization conversion state, the actuator 123B inserts the second 1/2 wavelength plate 123A between the second polarization beam splitter 103A and the third polarization beam splitter 105A. Thereby, the polarization state of each of the laser beams L1 and L2 that enters the second polarization beam splitter 103A and the third polarization beam splitter 105A from one to the other is converted from one of the first polarization and the second polarization to the other.

Conversely, in the polarization maintaining state, the actuator 123B retracts the second 1/2 wavelength plate 123A from between the second polarizing beam splitter 103A and the third polarizing beam splitter 105A. Thereby, the polarization state of each of the laser beams L1 and L2 entering from one of the second polarizing beam splitter 103A and the third polarizing beam splitter 105A to the other is maintained.

The driving of the actuators 121B and 123B, that is, the switching between the polarization conversion state and the polarization maintenance state of the first polarization conversion section 121 and the second polarization conversion section 123 is executed by the switching controller 32 under the control of the computer 31. When simultaneously measuring the positioning accuracy and straightness of the machine tool 91 in the X direction (hereinafter simply referred to as simultaneous measurement in the X direction), the computer 31 causes the first polarization converter 121 to maintain polarization using the switching controller 32. At the same time, the second polarization conversion unit 123 is switched to the polarization conversion state. As a result, the X external retroreflector 171 is irradiated with each of the laser beams L1 and L2 from the measuring device 14 (see FIGS. 4 and 6).

Further, when simultaneously measuring the positioning accuracy and straightness of the machine tool 91 in the Y direction (hereinafter simply referred to as simultaneous measurement in the Y direction), the computer 31 controls the first polarization converter 121 using the switching controller 32. While switching to the polarization conversion state, the second polarization conversion section 123 is also switched to the polarization maintenance state. Thereby, each laser beam L1, L2 is irradiated from the measuring device 14 to the Y external retroreflector 172 (see FIGS. 7 and 8).

Furthermore, when simultaneously measuring the positioning accuracy and straightness of the machine tool 91 in the Z direction (hereinafter simply referred to as simultaneous measurement in the Z direction), the computer 31 uses the switching controller 32 to control the first polarization conversion unit 121 and the straightness of the machine tool 91 in the Z direction. The second polarization converter 123 is switched to a polarization maintaining state. As a result, the Z external retroreflector 173 is irradiated with each of the laser beams L1 and L2 from the measuring device 14 (see FIGS. 9 and 10).

<Simultaneous measurement in X direction: 1st laser beam>
FIG. 4 is a ray diagram of the first laser beam L1 in simultaneous measurement in the X direction. Note that in FIG. 4, illustration of the second laser beam L2 is omitted. Further, reference numeral 300 in FIG. 4 is a top view of the measuring device 14 seen from the +Z direction side, and reference numeral 400 is a side view of the measuring device 14 seen from the −Y direction side (FIGS. 6, 7 to 7 described later). The same applies to Figure 10).

As shown in FIG. 4, the first laser beam L1 emitted from the first exit port 11A in the +X direction is polarized and separated by the first polarizing beam splitter 101A. Hereinafter, the first polarized light of the first laser beam L1 that passes through the first polarizing beam splitter 101A is referred to as "first measurement light L1M" (indicated by a solid line in the figure), and is on the -Y direction side at the first polarizing beam splitter 101A. The second polarized light of the first laser beam L1 that is reflected is referred to as "first reference light L1R" (indicated by a dotted line in the figure).

The first reference light L1R is reflected by the first polarizing beam splitter 101A toward the common retroreflector 101B, is retroreflected by the common retroreflector 101B toward the first polarizing beam splitter 101A, and is further retroreflected by the first polarizing beam splitter 101A. It is reflected in the -X direction by 101A. The first reference beam L1R is retroreflected by the common retroreflector 101B, thereby changing the incident position of the first laser beam L1 on the first polarizing beam splitter 101A and emitting it from the first polarizing beam splitter 101A in the −X direction. The emission position of the first reference light L1R satisfies a point-symmetric relationship with respect to the X-axis.

The first measuring light L1M (first polarized light) passes through the first polarizing beam splitter 101A, then passes through the second polarizing beam splitter 103A, and enters the second 1/2 wavelength plate 123A. Thereby, the polarization state of the first measurement light L1M (first polarized light) is converted from the first polarized light to the second polarized light. The first measurement light L1M (second polarized light) transmitted through the second 1/2 wavelength plate 123A is transmitted through the third polarization beam splitter 105A and the fourth polarization beam splitter 107A to the X external retroreflector 171. incident.

FIG. 5 is a front view of the X external retroreflector 171 viewed from the +X direction side. Note that the symbol F1 in FIG. 5 is the incident position of the first measurement light L1M (second polarized light) to the X external retroreflector 171, and the symbol F2 is the first measurement light emitted from the X external retroreflector 171. The emission position of L1M (second polarized light) is shown. Further, as will be explained in detail later in FIG. 6, the symbol G1 is the incident position of the second measurement light L2M (second polarized light) to the The output position of the second measurement light L2M (second polarized light) is shown. Further, the symbol CO in the figure indicates the center position (X axis) of the X external retroreflector 171.

The first measuring light L1M (second polarized light) incident on the position F1 of the X external retroreflector 171 is retroreflected by the X external retroreflector 171, thereby changing the position with respect to the center position CO (X axis). The light is emitted in the −X direction from a point F2 symmetrical to F1.

Returning to FIG. 4, the first measurement light L1M (second polarized light) retroreflected by the The light is incident on the 1/2 wavelength plate 123A. Thereby, the polarization state of the first measurement light L1M (second polarized light) is converted from the second polarized light to the first polarized light.

The first measurement light L1M (first polarized light) transmitted through the second 1/2 wavelength plate 123A passes through the second polarized beam splitter 103A and the first polarized beam splitter 101A, and exits from the first polarized beam splitter 101A to - The light is emitted in the X direction. As shown in FIG. 5, the first measurement light L1M is retroreflected by the X external retroreflector 171, thereby changing the incident position of the first laser beam L1 on the first polarizing beam splitter 101A and The emission position of the first measurement light L1M emitted from the -X direction side satisfies a point-symmetric relationship with respect to the X-axis. Therefore, the first measuring light L1M and the first reference light L1R are emitted from the same emitting position of the first polarizing beam splitter 101A in the −X direction and enter the receiver section 127, which will be described later.

<Simultaneous measurement in X direction: 2nd laser beam>
FIG. 6 is a ray diagram of the second laser beam L2 during simultaneous measurement in the X direction. Note that in FIG. 6, illustration of the first laser beam L1 is omitted.

As shown in FIG. 6 and the previously described FIG. 5, the second laser beam L2 emitted from the second exit port 11B in the +X direction is polarized and separated by the first polarizing beam splitter 101A. Hereinafter, the first polarized light of the second laser beam L2 that passes through the first polarizing beam splitter 101A is referred to as "second measurement light L2M" (indicated by a solid line in the figure), and is directed toward the -Y direction side by the first polarizing beam splitter 101A. The second polarized light of the reflected second laser beam L2 is referred to as "second reference light L2R" (indicated by a dotted line in the figure).

The second reference light L2R, like the first reference light L1R, is reflected by the first polarizing beam splitter 101A in the -X direction after passing through the common retroreflector 101B from the first polarizing beam splitter 101A. The second reference beam L2R is retroreflected by the common retroreflector 101B, so that the incident position of the second laser beam L2 on the first polarizing beam splitter 101A and the position of the second laser beam L2 being emitted from the first polarizing beam splitter 101A in the −X direction are changed. The emission position of the second reference light L2R satisfies a point-symmetric relationship with respect to the X-axis.

The second measurement light L2M (first polarized light) passes through the first polarization beam splitter 101A and the second polarization beam splitter 103A, and then enters the second 1/2 wavelength plate 123A. Thereby, the polarization state of the second measurement light L2M (first polarized light) is converted from the first polarized light to the second polarized light. The second measurement light L2M (second polarized light) transmitted through the second 1/2 wavelength plate 123A is transmitted through the third polarization beam splitter 105A and the fourth polarization beam splitter 107A.

The second measurement light L2M (second polarized light) that has passed through the fourth polarizing beam splitter 107A passes through the quarter-wave plate 107C, enters the position G1 of the X external retroreflector 171, and enters the X external retroreflector 171. By being retro-reflected at the center position CO (X-axis), the light beam is emitted from a position G2 point-symmetrical to the position G1 in the −X direction, and is transmitted through the quarter-wave plate 107C again. At this time, the second measurement light L2M (second polarized light) passes through the quarter-wave plate 107C twice between the fourth polarization beam splitter 107A and the X external retroreflector 171, so that the polarization state is changed. The second polarized light is converted into the first polarized light.

The second measuring light L2M (first polarized light) transmitted through the quarter-wave plate 107C is reflected by the fourth polarizing beam splitter 107A toward the retroreflector 107B, and then reflected by the retroreflector 107B to the fourth polarizing beam splitter 107A. The light is then retroreflected toward the X external retroreflector 171 by the fourth polarizing beam splitter 107A. As a result, the second measurement light L2M (first polarized light) passes through the quarter-wave plate 107C, is retroreflected by the X external retroreflector 171, and passes through the quarter-wave plate 107C again. As a result, the second measurement light L2M (first polarized light) passes through the quarter-wave plate 107C twice, thereby converting the polarization state from the first polarized light to the second polarized light. As a result, the second measurement light L2M (second polarized light) is retroreflected twice by the X external retroreflector 171, and then passes through the fourth polarization beam splitter 107A and proceeds in the −X direction.

The second measurement light L2M (second polarized light) that has passed through the fourth polarization beam splitter 107A passes through the third polarization beam splitter 105A and enters the second half-wave plate 123A. Thereby, the polarization state of the second measurement light L2M (second polarized light) is converted from the second polarized light to the first polarized light.

The second measurement light L2M (first polarized light) transmitted through the second half-wave plate 123A passes through the second polarized beam splitter 103A and the first polarized beam splitter 101A, and exits from the first polarized beam splitter 101A to - The light is emitted in the X direction.

The second measurement light L2M is retroreflected by the X external retroreflector 171, thereby changing the incident position of the second laser beam L2 on the first polarizing beam splitter 101A and emitting it from the first polarizing beam splitter 101A in the −X direction. The emission position of the second measurement light L2M (first polarized light) satisfies a relationship of approximately point symmetry with respect to the X-axis. Note that "approximate point symmetry" means that complete point symmetry does not occur when the X external retroreflector 171 is displaced in the YZ direction, as shown in FIG. 12, which will be described later.

Therefore, the second measurement light L2M and the second reference light L2R are at substantially the same emission position of the first polarizing beam splitter 101A, and the emission positions of the first measurement light L1M and the first reference light L1R are different from each other. The light is emitted from different positions in the −X direction and enters a fifth polarizing beam splitter 125A, which will be described later.

<Simultaneous measurement in Y direction: 1st laser beam>
FIG. 7 is a ray diagram of the first laser beam L1 during simultaneous measurement in the Y direction. Note that in FIG. 7, illustration of the second laser beam L2 is omitted.

As shown in FIG. 7, the first laser beam L1 emitted from the first exit port 11A in the +X direction is polarized and separated into a first measurement light L1M and a first reference light L1R by a first polarization beam splitter 101A. . The first reference light L1R follows the same path as the first reference light L1R shown in FIG. 4 described above, and is emitted from the first polarization beam splitter 101A in the −X direction.

The first measurement light L1M (first polarized light) transmitted through the first polarization beam splitter 101A is incident on the first half-wave plate 121A. Thereby, the polarization state of the first measurement light L1M (first polarized light) is converted from the first polarized light to the second polarized light. The first measuring light L1M (second polarized light) transmitted through the first half-wave plate 121A enters the second polarizing beam splitter 103A, and is transmitted to the Y external retroreflector 172 by the second polarizing beam splitter 103A. reflected towards.

The first measurement light L1M (second polarized light) incident on the Y external retroreflector 172 is retroreflected by the Y external retroreflector 172, and then enters the second polarization beam splitter 103A, 103A toward the first half-wave plate 121A in the −X direction. The polarization state of the first measurement light L1M (second polarized light) incident on the first half-wave plate 121A is converted from the second polarized light to the first polarized light.

The first measurement light L1M (first polarized light) transmitted through the first half-wave plate 121A follows the same path as the first measurement light L1M (first polarized light) shown in FIG. , is emitted from the first polarizing beam splitter 101A in the -X direction. As a result, the first measuring light L1M and the first reference light L1R are emitted from the same emitting position of the first polarizing beam splitter 101A in the -X direction and enter the receiver section 127, which will be described later.

<Simultaneous measurement in Y direction: 2nd laser beam>
FIG. 8 is a ray diagram of the second laser beam L2 during simultaneous measurement in the Y direction. Note that in FIG. 8, illustration of the first laser beam L1 is omitted.

As shown in FIG. 8, the second laser beam L2 emitted from the second exit port 11B in the +X direction is polarized and separated into a second measurement light L2M and a second reference light L2R by the first polarization beam splitter 101A. Ru. The second reference light L2R follows the same path as the second reference light L2R shown in FIG. 6 described above, and is emitted from the first polarizing beam splitter 101A in the −X direction.

The second measurement light L2M (first polarized light) transmitted through the first polarization beam splitter 101A is incident on the first half-wave plate 121A. Thereby, the polarization state of the second measurement light L2M (first polarized light) is converted from the first polarized light to the second polarized light. Then, the second measurement light L2M (second polarized light) transmitted through the first 1/2 wavelength plate 121A enters the second polarization beam splitter 103A, and is transmitted to the Y external retroreflector 172 by the second polarization beam splitter 103A. reflected towards.

The second measuring light L2M (second polarized light) reflected by the second polarizing beam splitter 103A passes through the quarter-wave plate 103C, enters the Y external retroreflector 172, and is reflected by the Y external retroreflector 172. By being retroreflected, the light is emitted in the −Y direction and passes through the quarter-wave plate 103C again. At this time, the second measurement light L2M (second polarized light) passes through the quarter-wave plate 103C twice between the second polarization beam splitter 103A and the Y external retroreflector 172, so that the polarization state is changed. The second polarized light is converted into the first polarized light.

The second measurement light L2M (first polarized light) that has passed through the quarter-wave plate 103C passes through the second polarization beam splitter 103A and enters the retroreflector 103B. It is retroreflected toward 103A and transmitted through the second polarizing beam splitter 103A. As a result, the second measurement light L2M (first polarized light) passes through the quarter-wave plate 103C, is retroreflected by the Y external retroreflector 172, and passes through the quarter-wave plate 103C again. As a result, the second measurement light L2M (first polarized light) passes through the quarter-wave plate 103C twice, thereby converting the polarization state from the first polarized light to the second polarized light. As a result, the second measuring light L2M (second polarized light) is retroreflected twice by the Y external retroreflector 172, and then enters the second polarizing beam splitter 103A. It is reflected toward the 1/2 wavelength plate 121A.

The polarization state of the second measurement light L2M (second polarized light) incident on the first half-wave plate 121A is converted from the second polarized light to the first polarized light.

The second measurement light L2M (first polarized light) transmitted through the second 1/2 wavelength plate 123A follows the same path as the second measurement light L2M (first polarized light) shown in FIG. , is emitted from the first polarizing beam splitter 101A in the -X direction. Thereby, the second measurement light L2M and the second reference light L2R are emitted in the -X direction from substantially the same emitting position of the first polarization beam splitter 101A, and enter a fifth polarization beam splitter 125A, which will be described later.

<Simultaneous measurement in Z direction: 1st laser beam>
FIG. 9 is a ray diagram of the first laser beam L1 during simultaneous measurement in the Z direction. Note that in FIG. 9, illustration of the second laser beam L2 is omitted.

As shown in FIG. 9, the first laser beam L1 emitted from the first exit port 11A in the +X direction is polarized and separated into a first measurement light L1M and a first reference light L1R by the first polarization beam splitter 101A. Ru. The first reference light L1R follows the same path as the first reference light L1R shown in FIGS. 4 and 7 described above, and is emitted from the first polarizing beam splitter 101A in the −X direction.

The first measurement light L1M (first polarized light) transmitted through the first polarization beam splitter 101A is transmitted through the second polarization beam splitter 103A, and then reflected by the third polarization beam splitter 105A toward the Z external retroreflector 173. Ru.

The first measurement light L1M (first polarized light) incident on the Z external retroreflector 173 is retroreflected by the Z external retroreflector 173, and then enters the third polarization beam splitter 105A, 105A toward the second polarizing beam splitter 103A in the −X direction.

The first measurement light L1M (first polarization) reflected in the -X direction by the third polarization beam splitter 105A takes the same path as the first measurement light L1M (first polarization) shown in FIG. , and is emitted from the first polarizing beam splitter 101A in the −X direction. As a result, the first measuring light L1M and the first reference light L1R are emitted from the same emitting position of the first polarizing beam splitter 101A in the -X direction and enter the receiver section 127, which will be described later.

<Simultaneous measurement in Z direction: 2nd laser beam>
FIG. 10 is a ray diagram of the second laser beam L2 during simultaneous measurement in the Z direction. Note that in FIG. 10, illustration of the first laser beam L1 is omitted.

As shown in FIG. 10, the second laser beam L2 emitted from the second exit port 11B in the +X direction is polarized and separated into a second measurement light L2M and a second reference light L2R by the first polarization beam splitter 101A. Ru. The second reference light L2R follows the same path as the second reference light L2R shown in FIGS. 6 and 8 described above, and is emitted from the first polarizing beam splitter 101A in the −X direction.

The second measurement light L2M (first polarized light) transmitted through the first polarization beam splitter 101A is transmitted through the second polarization beam splitter 103A, and then reflected by the third polarization beam splitter 105A toward the Z external retroreflector 173. Ru.

The second measuring light L2M (first polarized light) reflected by the third polarizing beam splitter 105A passes through the quarter-wave plate 105C, enters the Z external retroreflector 173, and is reflected by the Z external retroreflector 173. By being retroreflected, the light is emitted in the −Z direction and passes through the quarter-wave plate 105C again. At this time, the second measurement light L2M (first polarized light) passes through the quarter-wave plate 105C twice between the third polarization beam splitter 105A and the Z external retroreflector 173, so that the polarization state is changed. The first polarized light is converted into the second polarized light.

The second measuring light L2M (second polarized light) that has passed through the quarter-wave plate 105C passes through the third polarizing beam splitter 105A and enters the retroreflector 105B. It is retroreflected toward 105A and transmitted through the third polarizing beam splitter 105A. Thereby, the second measurement light L2M (second polarized light) passes through the quarter-wave plate 105C, is retroreflected by the Z external retroreflector 173, and passes through the quarter-wave plate 105C again. As a result, the second measurement light L2M (second polarized light) passes through the quarter-wave plate 103C twice, thereby converting the polarization state from the second polarized light to the first polarized light. As a result, the second measuring light L2M (second polarized light) is retroreflected twice by the Z external retroreflector 173, and then enters the third polarizing beam splitter 105A. It is reflected toward the two-polarization beam splitter 103A.

The second measurement light L2M (first polarization) that has entered the second polarization beam splitter 103A follows the same path as the second measurement light L2M (first polarization) shown in FIG. The light is emitted from the polarizing beam splitter 101A in the −X direction. As a result, the second measurement light L2M and the second reference light L2R are emitted in the -X direction from substantially the same emission position of the first polarization beam splitter 101A, and enter a fifth polarization beam splitter 125A, which will be described later.

As described above, by controlling the switching of the first polarization converter 121 and the second polarization converter 123, the light beams selectively reflected from the first polarization beam splitter 101A by each of the external retroreflectors 171 to 173 are The first measurement light L1M (first polarized light) and the first reference light L1R (second polarized light) reflected by the common retroreflector 101B are emitted to the receiver section 127 from the same position. At the same time, the second measuring light L2M (first polarized light) selectively reflected from the first polarizing beam splitter 101A by each external retroreflector 171 to 173 and the second measuring light L2M (first polarized light) reflected by the common retroreflector 101B. The reference light L2R (second polarized light) is emitted from substantially the same position to the fifth polarized beam splitter 125A.

[Positioning accuracy measurement]
FIG. 11 is a schematic diagram showing the configuration of the receiver section 127. As shown in FIG. 11, the receiver section 127 (corresponding to the first detection section) receives the first measurement light L1M and the first reference light L1R incident from the first polarization beam splitter 101A for each simultaneous measurement in three axial directions. Four-phase interference signals SG1 to SG4 having mutually different phases are generated and the interference signals SG1 to SG4 are detected. Note that the first measurement light L1M and the first reference light L1R entering from the first polarization beam splitter 101A do not interfere with each other because their polarization directions are orthogonal to each other.

The receiver section 127 is used in a fringe counting interference method, and includes a non-polarizing beam splitter 130, a half-wave plate 131, a polarizing beam splitter 132, a 45-degree right-angle prism 133, and a 45-degree right-angle prism 135. , a quarter wavelength plate 136, a half wavelength plate 137, a polarizing beam splitter 138, a 45-degree right angle prism 139, four condensing lenses 140, and four photodetectors 141.

The non-polarizing beam splitter 130 splits the first measurement light L1M and the first reference light L1R selectively emitted from the first polarization beam splitter 101A for each simultaneous measurement in three axial directions into two, and transmits one of them. The light is emitted towards the 1/2 wavelength plate 131 and the other is reflected towards the 45 degree right angle prism 135.

The 1/2 wavelength plate 131 rotates the polarization directions of the first measurement light L1M and the first reference light L1R incident from the non-polarizing beam splitter 130 by 45 degrees, and then outputs them to the polarizing beam splitter 132.

The polarization beam splitter 132 polarizes and separates the first measurement light L1M and the first reference light L1R that have entered from the half-wave plate 131, and directs the first measurement light L1M and the first reference light L1R toward the condenser lens 140. At the same time, it is reflected toward the 45-degree right angle prism 133. At this time, the first measurement light L1M and the first reference light L1R interfere, so that, for example, the interference signal SG1 with a phase of 0° enters the condenser lens 140, and the interference signal SG2 with a phase of 180° enters the 45° right-angle prism. 133. Note that instead of providing the 1/2 wavelength plate 131, the polarizing beam splitter 132 may be tilted by 45 degrees.

The 45-degree right-angle prism 133 reflects the interference signal SG2 incident from the polarizing beam splitter 132 toward the condenser lens 140.

The 45-degree right-angle prism 135 reflects the first measurement light L1M and the first reference light L1R that have entered from the non-polarizing beam splitter 130 toward the quarter-wave plate 136.

The quarter-wave plate 136 shifts the phases of the first measurement light L1M and the first reference light L1R incident from the 45-degree right-angle prism 135 by 90 degrees, and then shifts the first measurement light L1M and the first reference light L1R by 1 The light is emitted toward the /2 wavelength plate 137.

The half-wave plate 137 rotates the polarization directions of the first measurement light L1M and the first reference light L1R that have entered from the quarter-wave plate 136 by 45 degrees, and then outputs them to the polarization beam splitter 138.

The polarization beam splitter 138 polarizes and separates the first measurement light L1M and the first reference light L1R that have entered from the 1/2 wavelength plate 137, and directs the first measurement light L1M and the first reference light L1R toward the condenser lens 140. At the same time, it is reflected toward the 45-degree right-angle prism 139. At this time, the first measurement light L1M and the first reference light L1R interfere, so that, for example, an interference signal SG3 with a phase of 90° enters the condenser lens 140, and an interference signal SG4 with a phase of 270° enters the 45° right-angle prism. 139.

The 45-degree right-angle prism 139 reflects the interference signal SG4 incident from the polarizing beam splitter 138 toward the condenser lens 140.

Each condenser lens 140 condenses the four-phase interference signals SG1 to SG4 onto four photodetectors 141, respectively. The four photodetectors 141 receive and photoelectrically convert the interference signals SG1 to SG4, respectively, and then output them to the positioning accuracy signal processing unit 16 via the optical fiber 122. Note that the interference signals SG1 to SG4 repeat their strength and weakness in a sinusoidal manner as the optical path length of the first measurement light L1M changes according to the relative movement of the measurement device 14 with respect to each of the external retroreflectors 171 to 173.

The positioning accuracy signal processing unit 16 (corresponding to the positioning accuracy detection section) detects each of the three axial directions based on the detection results of the four-phase interference signals SG1 to SG4 input from the receiver section 127 for each simultaneous measurement of the three axial directions. Calculate the positioning accuracy and its correction value.

Specifically, the positioning accuracy signal processing unit 16 generates a first difference signal between an interference signal SG1 having a phase of 0° and an interference signal SG2 having a phase of 180°, and also generates a first difference signal between an interference signal SG3 having a phase of 90° and an interference signal SG3 having a phase of 270°. A second difference signal is generated between the interference signal SG4 and the interference signal SG4. Thereby, it is possible to remove the DC component included in each of the interference signals SG1 to SG4, double the amplitude of the signal, and remove errors caused by variations in the amount of light. Further, by using the first difference signal and the second difference signal whose phases are shifted by 90 degrees, it is possible to determine the direction of relative movement of the measuring device 14. The positioning accuracy signal processing unit 16 calculates a count number to be converted into a distance in a calculation unit (not shown) based on the first difference signal and the second difference signal. Then, the calculation unit calculates the distance from the measurement device 14 to the measurement target (any one of the external retroreflectors 171 to 173) based on the obtained count number.

During simultaneous measurement in the X direction, the positioning accuracy signal processing unit 16 processes each differential signal output from the receiver section 127 while the X external retroreflector 171 is moved relative to the measuring device 14 in the X direction. Based on this, the distance between the measuring device 14 and the X external retroreflector 171 is calculated. Next, the positioning accuracy signal processing unit 16 calculates the positioning accuracy in the X direction by comparing the calculated distance with the distance corresponding to the movement command from the NC controller 97.

Furthermore, during simultaneous measurement in the Y direction, the positioning accuracy signal processing unit 16 processes each difference output from the receiver section 127 while the Y external retroreflector 172 is moved relative to the measuring device 14 in the Y direction. The distance between the measuring device 14 and the Y external retroreflector 172 is calculated based on the signal. Next, the positioning accuracy signal processing unit 16 calculates the positioning accuracy in the Y direction by comparing the calculated distance with the distance corresponding to the movement command from the NC controller 97.

Furthermore, during simultaneous measurement in the Z direction, the positioning accuracy signal processing unit 16 processes each difference output from the receiver section 127 while the Z external retroreflector 173 is moved relative to the measuring device 14 in the Z direction. The distance between the measuring device 14 and the Z external retroreflector 173 is calculated based on the signal. Next, the positioning accuracy signal processing unit 16 calculates the positioning accuracy in the Z direction by comparing the calculated distance with the distance corresponding to the movement command from the NC controller 97.

Furthermore, the positioning accuracy signal processing unit 16 calculates correction values for the positioning accuracy in the three axial directions, based on the measurement results of the positioning accuracy in the three axial directions.

In this embodiment, a fringe count interference method is used to measure the positioning accuracy in each of the three axial directions, but various known interference methods such as a heterodyne method may also be used.

[Straightness measurement]
Returning to FIGS. 3 and 6, the fifth polarization beam splitter 125A (corresponding to the fifth polarization separation element) is configured to combine the second measurement light L2M (first polarization) incident from the first polarization beam splitter 101A and the second reference light L2M (first polarization). Polarization separation is performed on L2R (second polarized light). The fifth polarizing beam splitter 125A transmits the second measurement light L2M and outputs it to the measurement photodetector 125C, and reflects (emits) the second reference light L2R to the correction photodetector 125B.

The correction photodetector 125B (corresponding to the third detection section) receives the second reference light L2R and generates a light reception signal indicating the position coordinates of the second reference light L2R (spot light) within the light receiving surface of the correction photodetector 125B. , and output to the straightness signal processing unit 15 via the electric cable 35.

The measurement photodetector 125C (corresponding to the second detection section) receives the second measurement light L2M and generates a light reception signal indicating the position coordinates of the second measurement light L2M (spot light) within the light receiving surface of the measurement photodetector 125C. , and output to the straightness signal processing unit 15 via the electric cable 35.

The straightness signal processing unit 15 (corresponding to the straightness detection section) receives the received light signal of the second reference light L2R input from the correction photodetector 125B and the measurement photodetector 125C for each simultaneous measurement in three axial directions. Based on the received light signal of the second measurement light L2M, the straightness and its correction value are calculated for each of the three axial directions.

During simultaneous measurement in the X direction, the straightness signal processing unit 15 receives signals from the correction photodetector 125B and the measurement photodetector 125C while the X external retroreflector 171 is moved relative to the measurement device 14 in the X direction. The position coordinates of the second measurement light L2M and the second reference light L2R are compared based on the received light signals respectively input. Then, the straightness signal processing unit 15 calculates the displacement of the X external retroreflector 171 in the YZ direction while the X external retroreflector 171 is relatively moved in the X direction. Thereby, the straightness in the X direction is calculated by the straightness signal processing unit 15.

In addition, during simultaneous measurement in the Y direction, the straightness signal processing unit 15 controls the correction photodetector 125B and the measurement photodetector while the Y external retroreflector 172 is moved relative to the measurement device 14 in the Y direction. The displacement of the Y external retroreflector 172 in the XZ directions is calculated based on the received light signals inputted from the respective Y external retroreflectors 125C. Thereby, the straightness in the Y direction is calculated by the straightness signal processing unit 15.

Furthermore, during simultaneous measurement in the Z direction, the straightness signal processing unit 15 controls the correction photodetector 125B and the measurement photodetector while the Z external retroreflector 173 is moved relative to the measurement device 14 in the Z direction. The displacement of the Z external retroreflector 173 in the X and Y directions is calculated based on the received light signals inputted from the respective sensors 125C. Thereby, the straightness in the Z direction is calculated by the straightness signal processing unit 15.

Furthermore, the straightness signal processing unit 15 calculates correction values for the straightness in the three axial directions, based on the measurement results of the straightness in the three axial directions.

[Displacement expansion]
In this embodiment, during simultaneous measurement in the X direction, the second measurement light L2M is reflected twice to the X external retroreflector 171 using the fourth polarizing beam splitter 107A, retroreflector 107B, and quarter-wave plate 107C. I'm letting you do it. Furthermore, during simultaneous measurement in the Y direction, the second measurement light L2M is reflected twice to the Y external retroreflector 172 using the second polarizing beam splitter 103A, retroreflector 103B, and quarter-wave plate 103C. . Furthermore, during simultaneous measurement in the Z direction, the second measurement light L2M is reflected twice to the Z external retroreflector 173 using the third polarizing beam splitter 105A, retroreflector 105B, and quarter-wave plate 105C. . As a result, as will be described later, the displacement of the X external retroreflector 171 in the YZ direction, the displacement of the Y external retroreflector 172 in the XZ direction, and the displacement of the Z external retroreflector 173 in the XY direction are each quadrupled. It can be enlarged and detected.

FIG. 12 is a model diagram for explaining displacement detection of the X external retroreflector 171. As shown in FIG. 12, the polarizing beam splitter 200A corresponds to the fourth polarizing beam splitter 107A, the retroreflector 200B corresponds to the retroreflector 107B, and the quarter-wave plate 200C corresponds to the quarter-wave plate 107C. However, the external retroreflector 202 corresponds to the X external retroreflector 171, and the measurement light LP corresponds to the second measurement light L2M. Note that FIG. 12 shows a case where the external retroreflector 202 is displaced by Δd in the Y direction when making a relative movement in the X direction.

As shown in FIG. 12, the measurement light LP incident on the polarizing beam splitter 200A includes a 1/4 wavelength plate 200C, an external retroreflector 202, a 1/4 wavelength plate 200C, as explained in FIG. The light is emitted from the polarizing beam splitter 200A through the polarizing beam splitter 200A, the retroreflector 200B, the polarizing beam splitter 200A, the quarter-wave plate 200C, the external retroreflector 202, and the quarter-wave plate 200C.

At this time, the measurement light LP is retroreflected twice by the external retroreflector 202, so that the emission position of the measurement light LP from the polarizing beam splitter 200A is such that the external retroreflector 202 is not displaced in the Y direction. It is displaced by Δd×4 compared to the case. Furthermore, although not shown, when the external retroreflector 202 is displaced by Δd in the Z direction, the output position of the measurement light LP from the polarizing beam splitter 200A is similarly displaced by Δd×4 in the Z direction. Thereby, displacement in the YZ direction can be measured with high resolution during simultaneous measurement in the X direction, and therefore accuracy in measuring straightness in the X direction can be improved.

In addition, the displacement of the Y external retroreflector 172 in the XZ direction during simultaneous measurement in the Y direction and the displacement of the Z external retroreflector 173 in the XY direction during simultaneous measurement in the Z direction are similarly magnified by 4 times. Therefore, the measurement accuracy of straightness in the YZ direction can be improved.

[Measurement system action]
FIG. 13 is a flowchart showing the flow of processing for simultaneous measurement of positioning accuracy and straightness in three axial directions by the measurement system 10 having the above configuration.

As shown in FIG. 13, each of the external retroreflectors 171 to 173 is set on the mounting table 93, the measuring device 14 is attached to the processing tool section 92, and the measuring device 14 and each of the external retroreflectors 171 to 173 are connected. After the position adjustment is completed, the laser light source 11 is turned on by an operator's manual operation or a control command from the computer 31. As a result, the first laser beam L1 is emitted from the first emission aperture 11A, and the second laser beam L2 is emitted from the second emission aperture 11B (step S1).

The computer 31 drives the actuators 121B and 123B via the switching controller 32 to retract the first half-wave plate 121A and insert the second half-wave plate 123A (step S2). . As a result, the first polarization converter 121 is switched to the polarization maintaining state, and the second polarization converter 123 is switched to the polarization converting state.

When step S2 is completed, as shown in FIGS. 4 and 6, the first measurement light L1M retroreflected by the Reference light L1R is emitted from measurement device 14 to receiver section 127. Thereby, the receiver unit 127 generates four-phase interference signals SG1 to SG4 from the first measurement light L1M and the first reference light L1R, and detects each interference signal SG1 to SG4 (step S3).

At the same time, the second reference light L2R reflected by the common retroreflector 101B is emitted from the measuring device 14 via the fifth polarizing beam splitter 125A to the correction photodetector 125B, and is also transmitted to the X external retroreflector 171. The reflected second measurement light L2M is emitted to the measurement photodetector 125C. As a result, the correction photodetector 125B detects the second reference light L2R, and the measurement photodetector 125C detects the second measurement light L2M (step S3).

Next, the computer 31 moves the X external retroreflector 171 relative to the measuring device 14 in the X direction by moving the mounting table 93 in the X direction. Then, the positioning accuracy signal processing unit 16 performs positioning in the X direction based on each differential signal output from the receiver section 127 while the X external retroreflector 171 is moved relative to the measuring device 14 in the X direction. Calculate the accuracy and its correction value.

At the same time, the straightness signal processing unit 15 receives light reception signals input from the correction photodetector 125B and the measurement photodetector 125C while the X external retroreflector 171 is moved relative to the measurement device 14 in the X direction. Based on this, the straightness in the X direction and its correction value are calculated.

This completes the measurement of positioning accuracy and straightness in the X direction (step S4).

When the measurement of positioning accuracy and straightness in the X direction is completed, the computer 31 drives the actuators 121B and 123B via the switching controller 32 to insert the first 1/2 wavelength plate 121A and insert the second 1/2 wavelength plate 121A. The two-wavelength plate 123A is retracted (step S5). As a result, the first polarization conversion section 121 is switched to the polarization conversion state, and the second polarization conversion section 123 is switched to the polarization maintenance state.

When step S5 is completed, as shown in FIG. 7 and FIG. Reference light L1R is emitted from measurement device 14 to receiver section 127. As a result, the receiver section 127 detects each of the interference signals SG1 to SG4 (step S6).

At the same time, the second reference light L2R reflected by the common retroreflector 101B is emitted from the measurement device 14 via the fifth polarizing beam splitter 125A to the correction photodetector 125B, and is also emitted to the Y external retroreflector 172. The reflected second measurement light L2M is emitted to the measurement photodetector 125C. As a result, the correction photodetector 125B detects the second reference light L2R, and the measurement photodetector 125C detects the second measurement light L2M (step S6).

Next, the computer 31 moves the mounting table 93 in the Y direction, thereby moving the Y external retroreflector 172 relative to the measuring device 14 in the Y direction. Then, the positioning accuracy signal processing unit 16 performs positioning in the Y direction based on each difference signal output from the receiver section 127 while the Y external retroreflector 172 is moved relative to the measuring device 14 in the Y direction. Calculate the accuracy and its correction value.

At the same time, while the Y external retroreflector 172 is moved relative to the measuring device 14 in the Y direction, the straightness signal processing unit 15 receives light reception signals input from the correction photodetector 125B and the measurement photodetector 125C. Based on this, the straightness in the Y direction and its correction value are calculated.

This completes the measurement of positioning accuracy and straightness in the Y direction (step S7).

When the measurement of the positioning accuracy and straightness in the Y direction is completed, the computer 31 drives the actuators 121B and 123B via the switching controller 32 to retract the first 1/2 wavelength plate 121A and move the second 1/2 wavelength plate 121A. The two-wavelength plate 123A is retracted (step S8). As a result, both the first polarization conversion section 121 and the second polarization conversion section 123 are switched to the polarization maintaining state.

When step S8 is completed, as shown in FIG. 9 and FIG. Reference light L1R is emitted from measurement device 14 to receiver section 127. As a result, the receiver section 127 detects each of the interference signals SG1 to SG4 (step S9).

At the same time, the second reference light L2R reflected by the common retroreflector 101B is emitted from the measuring device 14 via the fifth polarizing beam splitter 125A to the correction photodetector 125B, and is also transmitted to the Z external retroreflector 173. The second measurement light L2M reflected by the second measurement light L2M is emitted to the measurement photodetector 125C. As a result, the correction photodetector 125B detects the second reference light L2R, and the measurement photodetector 125C detects the second measurement light L2M (step S9).

Next, the computer 31 moves the Z external retroreflector 173 relative to the measuring device 14 in the Z direction by moving the processing tool section 92 in the Z direction. Then, the positioning accuracy signal processing unit 16 performs positioning in the Z direction based on each differential signal output from the receiver section 127 while the Z external retroreflector 173 is moved relative to the measuring device 14 in the Z direction. Calculate the accuracy and its correction value.

At the same time, while the Z external retroreflector 173 is moved relative to the measuring device 14 in the Z direction, the straightness signal processing unit 15 processes the received light signals input from the correction photodetector 125B and the measurement photodetector 125C. Based on this, the straightness in the Z direction and its correction value are calculated.

The measurement of positioning accuracy and straightness in the Z direction is thus completed (step S10).

[Effects of this embodiment]
As described above, in this embodiment, the positioning accuracy and straightness of the machine tool 91 in the three-axis directions can be measured without replacing the positioning accuracy measuring device and the straightness measuring device. . Further, it is possible to automatically perform a setup change operation for changing the measurement of positioning accuracy and straightness in each direction of the three axes. As a result, the positioning accuracy and straightness of the machine tool 91 in the three-axis directions can be efficiently measured.

[others]
In the above embodiment, the polarization states of the first polarization converter 121 and the second polarization converter 123 are automatically switched, but it may also be done manually.

In the above embodiment, the laser emission direction is sequentially switched to the X direction, Y direction, and Z direction. However, as described in Patent Document 1, in order to make orthogonal adjustment easy and accurate, the measurement beam is changed in at least one axis direction. may be ejected at all times. For example, each of the polarizing beam splitters 103A, 105A, and 107A of the above embodiment transmits all of the P-polarized light and reflects all of the S-polarized light in an ideal state, but in reality, it reflects a portion of the P-polarized light (leak light). However, part of the S-polarized light (leakage light) may be transmitted. In this case, the measuring device 14 of the above embodiment can be considered to be able to always emit at least one of the laser beams L1 and L2 in at least one axis direction of XYZ, similar to the device described in Patent Document 1. . Therefore, by providing a detection sensor that detects leakage light in at least one direction of the XYZ directions in the above embodiment, it is possible to easily and accurately perform the orthogonal adjustment similar to the device described in Patent Document 1 above.

In the above embodiments, plate-type polarization beam splitters have been described as examples of the first to fifth polarization separation elements of the present invention, but various known polarization separation elements can be used instead.

In the above embodiment, the quarter-wave plate 107C is provided on the optical path (outward path, return path) of the second measurement light L2M between the fourth polarizing beam splitter 107A and the X external retroreflector 171. A 1/2 wavelength plate may be provided only on either the outgoing path or the incoming path of the optical path of the measurement light L2M. That is, if the polarization state of the second measurement light L2M can be switched during one round trip between the fourth polarization beam splitter 107A and the X external retroreflector 171, the type of optical element is There are no particular limitations. Similarly, instead of the 1/4 wavelength plates 103C and 105C, a 1/2 wavelength plate or the like may be provided only on one of the outgoing path and the incoming path of the optical path of the second measurement light L2M.

In the above embodiment, the polarization state of each measurement light L1M, L2M is switched by the first 1/2 wavelength plate 121A and the second 1/2 wavelength plate 123A, but optical elements other than the 1/2 wavelength plate ( For example, the polarization state may be switched using two 1/4 wavelength plates.

In the above embodiment, the second measurement light L2M is reflected twice by each of the external retroreflectors 171 to 173, but the retroreflectors 103B, 105B, 107B and the quarter-wave plates 103C, 105C, 107C are omitted. Then, the second measurement light L2M may be reflected only once.

In the above embodiment, the X direction and the Y direction are the horizontal direction, and the Z direction is the vertical direction, but any of the three axial directions may be the horizontal direction or the vertical direction, and furthermore, each of the three axial directions may be the horizontal direction or the vertical direction. The direction of inclination may be inclined from the vertical direction.

In the embodiment described above, the laser light source 11 is provided outside the measuring device 14, but the laser light source 11 may be provided inside the measuring device 14. Further, a straightness signal processing unit 15 and a positioning accuracy signal processing unit 16 may be provided inside the measuring device 14.

In the above embodiment, the positioning accuracy and straightness measurement in the three-axis directions of the machine tool 91 was explained as an example, but machines equipped with various moving mechanisms that move in the three-axis directions, such as optical machines and measuring machines, The present invention can be applied to the measurement of positioning accuracy and straightness in three axial directions.

10 Measurement system 11 Laser light source 11A First emission port 11B Second emission port 14 Measuring device 15 Signal processing unit for straightness 16 Signal processing unit for positioning accuracy 31 Computer 32 Switching controller 33 Data communication cable 35 Electrical cable 91 Machine tool 92 Processing Tool section 93 Mounting table 97 NC controller 101A First polarizing beam splitter 101B Common retroreflector 103A Second polarizing beam splitter 103B Retroreflector 103C 1/4 wavelength plate 105A 3rd polarizing beam splitter 105B Retroreflector 105C 1/4 wavelength Plate 107A Fourth polarization beam splitter 107B Retroreflector 107C Quarter-wave plate 121 First polarization converter 121A Half-wave plate 121B Actuator 122 Optical fiber 123 Second polarization converter 123A Half-wave plate 123B Actuator 124 Light Fiber 125A Fifth polarizing beam splitter 125B Correction photodetector 125C Measurement photodetector 127 Receiver section 130 Non-polarizing beam splitter 131 1/2 wavelength plate 132 Polarizing beam splitter 136 1/4 wavelength plate 137 1/2 wavelength plate 138 Polarizing beam splitter 140 Condensing lens 141 Photodetector 171 First laser beam L1M First measuring beam L1R First reference beam L2 Second laser beam L2M Second measuring beam L2R Second reference beam LP Measuring beam SG1 to SG4 Interference signal

Claims (10)

In a measuring device that measures the positioning accuracy and straightness of a machine in three axes of the X direction, Y direction, and Z direction that are orthogonal to each other,
a light emitting section that emits a first laser beam and a second laser beam along one direction in the X direction from mutually different positions;
a first polarization separation element, a second polarization separation element, and a third polarization separation element provided along the one direction side from the light emitting part;
a common retroreflector provided at a position facing the first polarization separation element in the Y direction;
When mutually orthogonal linearly polarized lights are first polarized light and second polarized light, the polarization states of the first laser beam and the second laser beam are set as described above between the first polarized light splitting element and the second polarized light splitting element. a first polarization conversion unit capable of switching between a polarization conversion state in which one of the first polarization and the second polarization is converted into the other, and a polarization maintenance state in which the polarization state is maintained;
a second polarization converter capable of switching between the polarization conversion state and the polarization maintenance state between the second polarization separation element and the third polarization separation element;
Equipped with
The first polarized light splitting element outputs the first polarized light of the first laser beam and the second laser beam incident from the light emitting section to the second polarized light splitting element, and outputs the second polarized light to the second polarized light splitting element. The first polarized light that has entered the common retroreflector is emitted to the other side of the X direction, and the second polarized light that has been reflected and entered the common retroreflector is Emits in the other direction,
the second polarization splitting element outputs the first polarized light incident from one of the first polarization splitting element and the third polarization splitting element to the other of the first polarization splitting element and the third polarization splitting element; The second polarized light incident from the first polarization splitting element is emitted to a first external retroreflector provided on the Y direction side of the second polarization splitting element, and is reflected by the first external retroreflector. outputting the incident second polarized light to the first polarized light separation element;
The third polarization splitting element outputs the first polarized light incident from the second polarization splitting element to a second external retroreflector provided on the Z direction side of the third polarization splitting element, and The polarized light is emitted to a third external retroreflector provided on the one direction side of the third polarization separation element, and the first polarized light reflected and incident on the second external retroreflector is separated into the second polarization separation element. outputting the second polarized light that has been emitted to the element, reflected by the third external retroreflector, and entered the second polarization separation element;
The first polarization conversion unit and the second polarization conversion unit are configured to transmit the first laser beam and the second laser beam to the first external retroreflector, the second external retroreflector, and the third external retroreflector. A measurement device that performs output switching to switch beam output. When emitting the first laser beam and the second laser beam to the first external retroreflector, the first polarization conversion section switches to the polarization conversion state, and the second polarization conversion section switches to the polarization conversion state. Switch to maintenance state,
When emitting the first laser beam and the second laser beam to the second external retroreflector, the first polarization converter and the second polarization converter switch to the polarization maintaining state,
When emitting the first laser beam and the second laser beam to the third external retroreflector, the first polarization converter switches to the polarization maintaining state, and the second polarization converter switches to the polarization maintaining state. The measuring device according to claim 1, wherein the measuring device switches to a conversion state. The first polarization converter includes:
a first common polarization conversion element that converts one of the first polarized light and the second polarized light into the other;
In the polarization conversion state, the first common polarization conversion element is inserted between the first polarization separation element and the second polarization separation element, and in the polarization maintenance state, the first common polarization conversion element is inserted between the first polarization conversion element and the second polarization separation element. a first insertion/removal portion for retracting from between the first polarization separation element and the second polarization separation element;
The measuring device according to claim 1 or 2, comprising: The second polarization conversion section,
a second common polarization conversion element that converts one of the first polarization and the second polarization into the other;
In the polarization conversion state, the second common polarization conversion element is inserted between the second polarization separation element and the third polarization separation element, and in the polarization maintenance state, the second common polarization conversion element is inserted between the second polarization separation element and the third polarization separation element. a second insertion/removal portion for retracting from between the second polarization separation element and the third polarization separation element;
The measuring device according to any one of claims 1 to 3, comprising: a first polarization converter, which is provided on the optical path of the second laser beam between the second polarization separation element and the first external retroreflector, and converts one of the first polarized light and the second polarized light into the other; Motoko and
a first retroreflector provided at a position opposite to the first polarization conversion element with respect to the second polarization separation element in the Y direction; a first retroreflector that reflects the two laser beams to the second polarization separation element;
Equipped with
The second polarization separation element separates the first polarized light of the second laser beam incident from one of the first external retroreflector and the first retroreflector into the first external retroreflector and the first retroreflector. The measuring device according to any one of claims 1 to 4, wherein the measuring device emits light to the other side of the device. a second polarization converter, which is provided on the optical path of the second laser beam between the third polarization separation element and the second external retroreflector, and converts one of the first polarized light and the second polarized light into the other; Motoko and
a second retroreflector provided at a position opposite to the second polarization conversion element with respect to the third polarization separation element in the Z direction, and wherein a second retroreflector that reflects the two laser beams to the third polarization separation element;
Equipped with
The third polarization separation element separates the second polarized light of the second laser beam incident from one of the second external retroreflector and the second retroreflector into the second external retroreflector and the second retroreflector. The measuring device according to any one of claims 1 to 5, wherein the measuring device emits light to the other side of the device. A fourth polarization separation element provided between the third polarization separation element and the third external retroreflector, the fourth polarization separation element being incident from one of the third polarization separation element and the third external retroreflector. a fourth polarization splitting element that outputs the second polarized light to the other of the third polarization splitting element and the third external retroreflector;
a third polarization converter, which is provided on the optical path of the second laser beam between the fourth polarization separation element and the third external retroreflector, and converts one of the first polarized light and the second polarized light into the other; Motoko and
a third retroreflector provided at a position facing the fourth polarization separation element in the Z direction, the third retroreflector separating the second laser beam incident from the fourth polarization separation element into the fourth polarization separation element; a third retroreflector that reflects to the element;
Equipped with
The fourth polarization separation element separates the first polarized light of the second laser beam incident from one of the third external retroreflector and the third retroreflector into the third external retroreflector and the third retroreflector. The measuring device according to any one of claims 1 to 6, wherein the measuring device emits light to the other side of the device. The first polarized light separation element selectively reflects the first polarized light by the first external retroreflector, the second external retroreflector, and the third external retroreflector in accordance with the output switching. , the second polarized light reflected by the common retroreflector is emitted toward the other direction from different positions for each of the first laser beam and the second laser beam. Measuring device as described in Section. a first detection unit that detects an interference signal between the first polarized light and the second polarized light of the first laser beam emitted from the first polarization separation element in the other direction;
a fifth polarization separation element that polarizes and emits the first polarized light and the second polarized light of the second laser beam emitted from the first polarization separation element in the other direction;
a second detection unit that detects the first polarized light emitted from the fifth polarization separation element;
a third detection unit that detects the second polarized light emitted from the fifth polarization separation element;
Equipped with
In accordance with the emission switching, the first detection section detects the interference signal in each of the three axial directions, the second detection section detects the first polarized light, and the third detection section detects the second polarized light. 9. The measuring device according to claim 1, wherein: detecting. A measuring device according to claim 9;
a positioning accuracy detection unit that detects the positioning accuracy in each of the three axial directions based on a detection result obtained by the first detection unit detecting the interference signal in each of the three axial directions;
Detecting the straightness in each of the three axial directions based on the detection result of the first polarized light in each of the three axial directions by the second detection section and the detection result of the second polarized light in the third detection section. A straightness detection unit that performs
A measurement system equipped with.

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