JP2011064609A - Interferometer - Google Patents

Abstract

An interferometer capable of safely measuring a distance to a moving body is provided.
An interferometer 1A includes a dimming unit 3A configured to be capable of adjusting the amount of light emitted from the interferometer 1A, and whether or not the received light amounts of the light receiving units 47 and 49 are equal to or less than a predetermined first threshold value. When the first determination means and the first determination means determine that the amount of received light is equal to or less than the first threshold, a reduction signal that instructs the dimming means 3A to reduce the amount of light emitted from the interferometer 1A. Reduction signal output means for outputting. The dimming unit 3A reduces the amount of light emitted from the light source when a reduction signal is input. Therefore, when the interferometer 1A loses sight of the reflector 101, the light control means 3A reduces the amount of light emitted from the interferometer 1A, so that it interferes with people working around the interferometer 1A. The measurement light can be prevented from being irradiated from the total 1A, and the distance to the moving body 2 can be measured safely.
[Selection] Figure 5

Description

  The present invention relates to an interferometer.

Conventionally, for example, a tracking laser interferometer has been used as a measuring device for measuring the distance to a retroreflector attached to a moving body (see, for example, Patent Document 1).
The tracking laser interferometer described in Patent Document 1 divides laser light into measurement light and reference light, and emits the measurement light toward a retroreflector (retroreflector) attached to a moving body. Then, the retroreflector is tracked by controlling the emission direction of the laser light so that the deviation amount of the return light from the retroreflector falls within a predetermined range. The tracking laser interferometer described in Patent Document 1 reflects reference light on a reference surface, and uses interference light between the reference light reflected on the reference surface and return light from a retroreflector. Measure the distance to the retroreflector (moving body).

JP 2007-57522 A

  However, in such a tracking type laser interferometer, the measurement light deviates from the retroreflector, or an obstacle is positioned between the interferometer and the retroreflector, so that the return light from the retroreflector is generated. If the interferometer is not returned, the retroreflector is lost and measurement light continues to be emitted in the lost direction. Therefore, when measuring the distance to the retroreflector using such a tracking laser interferometer, when the interferometer loses sight of the retroreflector, it interferes with people working around the interferometer. There was a possibility that measurement light was irradiated from the meter.

  The objective of this invention is providing the interferometer which can measure the distance to a reflector safely.

The interferometer of the present invention includes a light source that emits light, a reflector that is attached to a moving body and reflects light emitted from the light source, and receives a light reflected by the reflector to receive a light reception signal. An interferometer comprising a light receiving means for outputting and a distance calculating means for calculating a distance to the reflector using the light receiving signal, wherein the light quantity emitted from the light source is adjustable. A first determination unit that determines whether the light reception amount of the light reception unit is equal to or less than a predetermined first threshold based on the light reception signal; and the first determination unit, wherein the light reception amount is equal to the first threshold value. When it is determined as follows, the dimming means includes a reduction signal output means for outputting a reduction signal for commanding a reduction in the amount of light emitted from the light source, and the dimming means receives the reduction signal. The amount of light emitted from the light source is reduced. And characterized in that.
Note that “reducing the amount of light emitted from the light source” includes stopping the emission of light from the light source.

  According to the present invention, the light emitted from the light source is detached from the reflector, or an obstacle is positioned between the interferometer and the reflector, so that the return light from the reflector does not return to the interferometer, When the interferometer loses sight of the reflector, the first determination unit determines that the amount of light received by the light receiving unit is equal to or less than a predetermined first threshold, and the reduction signal output unit outputs a reduction signal to the dimming unit. . Then, the dimming means to which the reduction signal is inputted reduces the amount of light emitted from the light source. Thus, in the present invention, when the return light from the reflector does not return to the interferometer and the interferometer loses sight of the reflector, the amount of light emitted from the light source can be reduced, and the interferometer It is possible to prevent a person working around the area from being irradiated with strong measuring light from the interferometer. Therefore, the distance to the reflector can be measured safely.

  In the interferometer according to the aspect of the invention, it is preferable that the dimming unit includes a shutter capable of blocking light emitted from the light source toward the reflector.

  According to the present invention, since the light control means includes the shutter, when a reduction signal is input, the light emitted from the light source toward the reflector is blocked by the shutter, thereby stopping the light emission by the light source. be able to. Therefore, it is possible to reliably prevent a person working around the interferometer from being irradiated with light from the interferometer. Moreover, since the light control means blocks the light emitted from the light source by the shutter, the configuration can be simplified, and the manufacturing cost of the light control means, and hence the manufacturing cost of the interferometer, can be reduced.

  In the interferometer according to the aspect of the invention, the dimming unit may include an optical variable attenuator that is disposed on an optical path of light emitted from the light source toward the reflector and can adjust an attenuation amount of transmitted light. preferable.

  According to the present invention, the dimming means includes the variable optical attenuator capable of adjusting the attenuation amount of the light transmitted through the dimming means, so that the light passing through the dimming means is attenuated to be emitted from the light source. The amount of light emitted can be reduced to a level that is safe for the eyes.

In the interferometer of the present invention, after the reduction signal output means outputs the reduction signal, a second determination is made to determine whether or not the light reception amount of the light reception means is greater than or equal to a predetermined second threshold based on the light reception signal. And when the second determination unit determines that the amount of received light is equal to or greater than the second threshold, a release signal that instructs the dimming unit to cancel the reduction in the amount of light emitted from the light source. It is preferable that a cancellation signal output unit is provided, and the dimming unit cancels the reduction in the amount of light emitted from the light source when the cancellation signal is input.
Note that the second threshold value may be equal to the first threshold value.

  According to the present invention, since the return light from the reflector does not return to the interferometer, the return light from the reflector is reduced in the state where the light control means reduces the amount of light emitted from the light source. In the case of returning to, the second determination unit determines that the amount of light received by the light receiving unit is equal to or greater than a predetermined second threshold value, and the release signal output unit outputs a release signal to the light control unit. Then, the dimming means to which the release signal is input cancels the reduction in the amount of light emitted from the light source, and returns the amount of light emitted from the light source to the original. Thus, in the present invention, when the return light from the reflector returns to the interferometer in a state where the light amount emitted from the light source is reduced, the light amount emitted from the light source can be restored. As a result, the interferometer can again measure the distance to the moving body.

  In the interferometer of the present invention, the reflector is configured so that the incident light and the reflected light are parallel, and the incident light and the reflected light are incident so that they are point-symmetric with respect to the center. The interferometer is a tracking laser interferometer that tracks the retroreflector so that the amount of deviation of the light reflected by the retroreflector falls within a predetermined range. Is preferred.

Here, when measuring a reflector attached to a moving body using a non-tracking interferometer, the interferometer must be installed in the moving direction of the moving body. Accordingly, every time the moving body is moved in a predetermined one-axis direction, an interferometer must be installed in the one-axis direction, which takes time.
On the other hand, according to the present invention, since the interferometer is a tracking laser interferometer, the retroreflector attached to the moving body can be tracked. Therefore, once the interferometer is installed, the distance to the retroreflector can be measured without changing the installation location, and the measurement can be easily performed.

[First Embodiment]
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a tracking laser interferometer 1 (hereinafter referred to as an interferometer 1) according to the present embodiment.
The interferometer 1 tracks the moving body 2 and measures the distance to the moving body 2. The moving body 2 is provided in an industrial machine that measures or processes an object by moving the moving body 2, for example, and is driven by the industrial machine. An example of the industrial machine is a three-dimensional measuring machine, and an example of the moving body is a slider of a three-dimensional measuring machine to which a probe for measuring an object is attached.

  As shown in FIG. 1, the interferometer 1 includes a retroreflector 101, a laser light source 102, a lens 103, a dimming means 3, a measuring optical system 4, a carriage 5, a reference sphere 104, a displacement meter 105, and a PC 6 (Personal Computer ).

  The retroreflector 101 is attached to the moving body 2. The retroreflector 101 converts the incident light so that the incident light and the reflected light are parallel, and the incident light and the reflected light are point-symmetric with respect to the center of the retroreflector 101. reflect. Therefore, when light is incident at a position away from the center, the incident light and the reflected light are deviated.

The laser light source 102 emits laser light.
The lens 103 condenses and collimates the laser light emitted from the laser light source 102 and incident via the optical fiber 106.

The light control means 3 is provided at the rear stage of the lens 103. The light control means 3 includes a shutter that can advance and retreat on the optical path of the laser light transmitted through the lens 103, and is configured to be able to block the laser light by arranging the shutter on the optical path of the laser light. ing.
The measurement optical system 4 is for measuring the displacement ΔL1 from the measurement optical system 4 to the retroreflector 101.

FIG. 2 is a diagram illustrating a configuration of the measurement optical system 4. Since the measurement optical system 4 has a known configuration, it will be briefly described here.
As shown in FIG. 2, the measurement optical system 4 includes a collimator lens 41, a polarizing beam splitter 42 (Polarizing Beam Splitter), λ / 4 plates 43 and 46, a plane mirror 44 as a reference surface, and a non-polarizing beam splitter 45 (Non- Polarizing Beam Splitter), light receiving means 47 and 49, and a polarizing plate 48. Among these, the light receiving means 47 includes a quadrant PD 471 (Photo Diode) and a signal processing circuit 472 (FIG. 1). The light receiving means 47 may include a two-dimensional PSD (Position Sensing Detector) instead of the four-divided PD 471. The light receiving means 49 includes a PD 491 (Photo Detector) and a signal processing circuit 492 (FIG. 2).

  In such a measurement optical system 4, the laser light emitted from the laser light source 102 and transmitted through the lens 103 is incident on the polarization beam splitter 42 through the optical fiber 107 and the collimator lens 41, and the reference light is transmitted by the splitter 42. And divided into measuring light. The reference light passes through the λ / 4 plate 43, is reflected by the plane mirror 44, passes through the λ / 4 plate 43 again, enters the polarization beam splitter 42, and is reflected by the splitter 42 toward the PD 491 side. .

  On the other hand, the measurement light passes through the non-polarizing beam splitter 45 and the λ / 4 plate 46, is emitted toward the retroreflector 101, is then reflected by the retroreflector 101 and becomes return light, and is again measured by the measurement optical system. 4 is incident. At this time, when the measurement light is incident on a position away from the center of the retroreflector 101, the measurement light is reflected with a deviation from the incident direction as described above. That is, the return light follows the optical path different from the optical path of the measurement light incident on the retroreflector 101 and enters the measurement optical system 4.

  Then, the return light incident on the measurement optical system 4 passes through the λ / 4 plate 46, and then a part thereof is reflected by the non-polarizing beam splitter 45 and received by the four-divided PD 471. At this time, the return light is incident with a deviation from the center of the light receiving surface of the quadrant PD 471 according to the amount of deviation. The four-divided PD 471 has a light receiving surface that is divided into four parts, top, bottom, left, and right, and outputs four light reception signals corresponding to the amount of return light incident on each division surface. These four light reception signals are signals corresponding to the return light shift amount ΔTr and the light reception amount of the four-divided PD 471. The 4-split PD 471 outputs the four received light signals to the PC 6 via the signal processing circuit 472 as a first received light signal corresponding to the return light shift amount ΔTr and the received light amount (FIG. 1).

  On the other hand, the remaining return light that has passed through the non-polarization beam splitter 45 becomes interference light with the reference light that has passed through the polarization beam splitter 42 and reflected by the plane mirror 44. The interference light between the return light and the reference light is transmitted through the polarizing plate 48 and then received by the PD 491. The PD 491 that has received the interference light between the return light and the reference light receives the second received light signal according to the displacement ΔL1 of the distance between the measurement optical system 4 and the retroreflector 101 and the received light amount via the signal processing circuit 492, and the PC 6. (FIG. 1).

  Returning to FIG. 1, the carriage 5 includes biaxial rotation mechanisms 51 and 52 that are orthogonal to each other, an azimuth motor 53 that drives the rotation mechanism 51, an elevation motor 54 that drives the rotation mechanism 52, and each motor 53, Motor drive circuits 55 and 56 for controlling 54 are provided. Among these, the measurement optical system 4 and the displacement meter 105 are fixed to the rotation mechanism 52. The reference sphere 104 is fixed to the rotation mechanisms 51 and 52 so that the center of the reference sphere 104 coincides with the point where the rotation axes of the rotation mechanisms 51 and 52 intersect. In the carriage 5, the rotation mechanisms 51 and 52 are driven by the motors 53 and 54, and change the emission direction of the measurement light by changing the azimuth angle and elevation angle of the measurement light.

  The displacement meter 105 is for measuring the displacement ΔL2 of the distance between the displacement meter 105 and the center of the reference sphere 104. The displacement meter 105 is a capacitance displacement meter or an overcurrent displacement meter, and includes a signal processing circuit 105A. The displacement meter 105 outputs a signal corresponding to the displacement ΔL2 of the distance between the displacement meter 105 and the center of the reference sphere 104 to the PC 6 via the signal processing circuit 105A.

FIG. 3 is a block diagram showing the PC 6.
As shown in FIG. 3, the PC 6 includes a determination unit 61 that is a first determination unit, a distance calculation unit 62, a carriage control unit 63, and a cutoff signal output unit 64.

  Based on the light reception signals output from the light receiving units 47 and 49, the determination unit 61 determines the received light amount of each of the light receiving units 47 and 49 to a predetermined first threshold value set for each of the light receiving units 47 and 49, respectively. It is determined whether or not:

  The distance calculation means 62 includes a second received light signal corresponding to the distance displacement ΔL1 between the measurement optical system 4 and the retroreflector 101 output from the light receiving means 49, and the displacement meter 105 output from the displacement gauge 105 and a reference. A displacement ΔL (= ΔL1 + ΔL2) of the distance from the center of the reference sphere 104 to the retroreflector 101 is calculated from the signal corresponding to the displacement ΔL2 of the distance from the center of the sphere 104. Then, the distance calculating means 62 calculates the distance from the center of the reference sphere 104 to the retroreflector 101 (moving body 2) from the displacement ΔL.

  Based on the first light reception signal output from the light receiving means 47, the carriage control means 63 outputs drive signals to the motor drive circuits 55 and 56 so that the return light shift amount ΔTr is within a predetermined range. The carriage 5 is controlled to direct the measurement light emission direction toward the retroreflector 101. Specifically, the carriage control means 63 matches the level of the light reception signals corresponding to the upper and lower divided surfaces among the four light reception signals constituting the first light reception signal corresponding to the amount of light received on each divided surface of the four-divided PD 471. By driving the carriage 5 to change the elevation angle of the measurement light, and driving the carriage 5 to change the azimuth angle of the measurement light so that the levels of the received light signals corresponding to the left and right divided surfaces coincide with each other. The measurement light is always emitted toward the center of the retroreflector 101.

  When the determination unit 61 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or less than a predetermined first threshold value, the cutoff signal output unit 64 drives the shutter to the light control unit 3. Outputs a cut-off signal that instructs to cut off the laser beam. In this embodiment, this cutoff signal becomes a reduction signal, and the cutoff signal output means 64 becomes a reduction signal output means.

Hereinafter, a method for measuring the distance to the moving body 2 by the interferometer 1 will be briefly described.
FIG. 4 is a flowchart showing the measurement method.
First, the interferometer 1 emits measurement light toward the retroreflector 101 attached to the moving body 2 by being operated by an operator or the like (ejecting step S1).
After the emission step S1, the light receiving unit 47 receives the return light from the retroreflector 101, and the light receiving unit 49 receives the interference light between the return light and the reference light (light receiving step S2).

  After the light receiving step S <b> 2, the determination unit 61 sets the light reception amounts of the light receiving units 47 and 49 for the light receiving units 47 and 49 based on the light reception signals output from the light receiving units 47 and 49, respectively. It is determined whether or not the predetermined first threshold value or less (determination step S3).

  In the determination step S <b> 3, when the determination unit 61 determines that the amount of light received by each of the light receiving units 47 and 49 is not equal to or less than the predetermined first threshold (S <b> 3: NO), the distance calculation unit 62 outputs from the light receiving unit 49. The distance to the retroreflector 101 (moving body 2) is calculated based on the second received light signal and the signal output from the displacement meter 105 (distance calculation step S4).

  After the distance calculation step S4, the carriage control unit 63 controls the carriage 5 based on the first light reception signal output from the light reception unit 47 so that the return light deviation amount ΔTr is within a predetermined range, and the measurement light. Is directed toward the retroreflector 101 (carriage control step S5). After the carriage control step S5, the process returns to the step S2, and the steps S2 to S5 are repeated, so that the retroreflector 101 is tracked and the retroreflector 101 is moved while the retroreflector 101 moves together with the moving body 2. The distance is continuously measured.

On the other hand, in the determination step S3, when the determination unit 61 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or less than a predetermined first threshold (S3: YES), the cutoff signal output unit 64 is Then, a blocking signal is output to the light control means 3 (blocking signal output step S6).
After the shut-off signal output step S6, the light control means 3 to which the shut-off signal has been input drives the shutter to shut off the laser light, and stops emission of the measurement light from the interferometer 1 (shut-off step S7).

According to the present embodiment as described above, the following effects can be obtained.
(1) Return light from the retroreflector 101 returns to the interferometer 1 when the measurement light deviates from the retroreflector 101 or an obstacle is positioned between the interferometer 1 and the retroreflector 101. First, when the interferometer 1 loses sight of the retroreflector 101, the light control means 3 stops the emission of the measurement light from the interferometer 1. It is possible to prevent the measurement light from being irradiated. Therefore, the distance to the retroreflector 101 can be measured safely.

(2) Since the light control means 3 includes a shutter, the laser light can be blocked by the shutter, and the emission of the measurement light from the interferometer 1 can be stopped. Accordingly, when the interferometer 1 loses sight of the retroreflector 101, the light control means 3 can stop the emission of the measurement light from the interferometer 1 and interfere with the person working around the interferometer 1. It is possible to reliably prevent the measurement light from being irradiated from the total 1. Moreover, since the light control means 3 should just be comprised from the drive part etc. for driving a shutter and a shutter, the structure of the light control means 3 can be simplified. Therefore, the manufacturing cost of the light control means 3 can be reduced, and the manufacturing cost of the interferometer 1 can be reduced.

(3) Since the interferometer 1 is a tracking laser interferometer, the retroreflector 101 attached to the moving body 2 can be tracked. Therefore, once the interferometer 1 is installed, the distance to the retroreflector 101 can be measured without changing the installation location, and the measurement can be easily performed.

[Second Embodiment]
FIG. 5 is a diagram showing a configuration of an interferometer 1A according to the second embodiment of the present invention. Henceforth, the same code | symbol is attached | subjected to the same functional part as the said 1st Embodiment, and those description is abbreviate | omitted or simplified.
In the first embodiment, the light control means 3 includes a shutter, and is configured to be able to stop emission of measurement light from the interferometer 1 by blocking laser light with the shutter. On the other hand, in the present embodiment, the dimming means 3A includes an optical variable attenuator, and adjusts the attenuation amount of the laser light transmitted through the dimming means 3A so that the measurement light emitted from the interferometer 1A is adjusted. It is characterized in that it is configured to be able to adjust the amount of light.

  Further, in the first embodiment, when the interferometer 1 loses sight of the retroreflector 101, the dimming unit 3 stops the emission of the measurement light from the interferometer 1. On the other hand, in this embodiment, when the interferometer 1A loses sight of the retroreflector 101, as will be described in detail later, the light amount of the measurement light emitted from the interferometer 1A by the dimmer 3A is reduced. However, when the return light from the retroreflector 101 returns to the interferometer 1A, the light amount of the measurement light emitted from the interferometer 1A by the dimming means 3A is restored again to A feature is that measurement is resumed.

FIG. 6 is a block diagram showing the PC 6 of this embodiment.
As shown in FIG. 6, the PC 6 of this embodiment includes a reduction signal output unit 64 </ b> A, a second determination unit 65, and a release signal output unit 66 in addition to the units 61 to 63 similar to those of the first embodiment. ing. The first determination unit 61 has the same function as the determination unit 61 of the first embodiment.

  When the first determination unit 61 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or less than a predetermined first threshold value, the reduction signal output unit 64A emits laser light to the dimming unit 3A. A reduction signal is output that commands to attenuate and reduce the amount of measurement light emitted from the interferometer 1A to a level safe for the eyes.

Based on the light reception signals output from the light receiving means 47 and 49, the second determination means 65 is a predetermined first set in which the amounts of light received by the light receiving means 47 and 49 are set for the light receiving means 47 and 49, respectively. It is determined whether or not the threshold value is 2 or more. In the present embodiment, the second threshold is set lower than the first threshold, but may be set to a value equal to the first threshold.
When the second determination unit 65 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or greater than a predetermined second threshold value, the release signal output unit 66 sends the laser light to the light control unit 3A. A cancellation signal is output that commands cancellation of attenuation, that is, cancellation of reduction in the amount of measurement light emitted from the interferometer 1A.

Hereinafter, a method for measuring the distance to the moving body 2 by the interferometer 1A will be briefly described.
FIG. 7 is a flowchart showing the measurement method.
S1 to S5 are the same as those in the first embodiment. Note that S3 is referred to as a first determination step S3 in the present embodiment.
In the first determination step S3, the first determination unit 61 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or less than a predetermined first threshold based on the light reception signals output from the light receiving units 47 and 49. (S3: YES), the reduction signal output means 64A outputs a reduction signal to the dimming means 3A (reduction signal output step S6).

After the reduction signal output step S6, the dimming unit 3A to which the reduction signal is input attenuates the laser light, and reduces the amount of measurement light emitted from the interferometer 1A to a level that is safe for the eyes (reduction). Step S7).
After the reduction step S7, the light receiving means 47 receives the return light from the retroreflector 101, and the light receiving means 49 receives the interference light between the return light and the reference light (light receiving step S8).

  After the light receiving step S8, the second determining means 65 determines the amount of light received by each of the light receiving means 47, 49 based on the light receiving signal output from each of the light receiving means 47, 49 to each of the light receiving means 47, 49. It is determined whether or not the predetermined second threshold value is exceeded (second determination step S9).

In the second determination step S9, when the second determination unit 65 determines that the amount of light received by each of the light receiving units 47 and 49 is not equal to or greater than the second threshold (S9: NO), the process returns to step S8.
On the other hand, in the second determination step S9, when the second determination unit 65 determines that at least one of the amounts of light received by the light receiving units 47 and 49 is equal to or greater than the second threshold (S9: YES), the release signal output unit. 66 outputs a release signal to the light control means 3A (release signal output step S10).

  After the release signal output step S10, the dimming means 3A to which the release signal is input cancels the attenuation of the laser beam and returns the amount of the measurement light emitted from the interferometer 1A to the original state (release step S11). After the canceling step S11, the process returns to the light receiving step S2.

According to the present embodiment as described above, the following effects can be obtained in addition to the effects (1) and (3) of the first embodiment.
(4) The dimming means 3A includes a variable optical attenuator that can adjust the attenuation amount of the laser light that passes through the dimming means 3A. Can be reduced to a light amount that is safe for the eyes.

(5) Since the return light from the retroreflector 101 does not return to the interferometer 1, the dimming means 3A returns from the retroreflector 101 in a state where the amount of measurement light emitted from the interferometer 1A is reduced. When the light returns to the interferometer 1, the dimming means 3A restores the amount of measurement light emitted from the interferometer 1A so that the interferometer 1A can measure the distance to the moving body 2 again. It becomes.

[Modification of Embodiment]
Note that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope in which the object of the present invention can be achieved are included in the present invention.
In each of the embodiments described above, the light control means 3 and 3A are arranged on the lens 103 side. Also good. The light control means 3 and 3A may be disposed between the laser light source 102 and the lens 103.
The interferometers 1 and 1A of the respective embodiments are tracking laser interferometers. However, when the moving body is moved only linearly, for example, the interferometers may not be tracking. In this case, by installing a non-tracking interferometer in the moving direction of the moving body, the distance to the moving body can be measured by the interferometer.

  The present invention can be used for an interferometer.

The block diagram which shows the interferometer which concerns on 1st Embodiment of this invention. The figure which shows the structure of the measurement optical system of the said embodiment. The block diagram which shows PC of the said embodiment. The flowchart which shows the measuring method by the interferometer of the said embodiment. The figure which shows the structure of the interferometer which concerns on 2nd Embodiment of this invention. The block diagram which shows PC of the said embodiment. The flowchart which shows the measuring method by the interferometer of the said embodiment.

DESCRIPTION OF SYMBOLS 1,1A Tracking type laser interferometer 2 Moving body 3, 3A Light control means 47, 49 Light receiving means 61 Determination means (first determination means)
62 Distance calculation means 64 Blocking signal output means (reduction signal output means)
64A reduction signal output means 65 Second determination means 66 Release signal output means 101 Retroreflector 102 Laser light source

Claims (5)

A light source that emits light, a reflector that reflects light emitted from the light source attached to a moving body, a light receiving unit that receives light reflected by the reflector and outputs a light reception signal; A distance calculating means for calculating a distance to the reflector using a received light signal, and an interferometer,
Dimming means configured to be capable of adjusting the amount of light emitted from the light source;
First determination means for determining whether the amount of light received by the light receiving means is equal to or less than a predetermined first threshold based on the light reception signal;
A reduction signal output means for outputting a reduction signal instructing the light control means to reduce the amount of light emitted from the light source when the first determination means determines that the amount of received light is equal to or less than the first threshold; With
The interferometer, wherein the dimming unit reduces the amount of light emitted from the light source when the reduction signal is input. The interferometer according to claim 1, wherein
The dimming unit includes a shutter capable of blocking light emitted from the light source toward the reflector. The interferometer according to claim 1 or 2,
The said light control means is arrange | positioned on the optical path of the light inject | emitted toward the said reflector from the said light source, and is equipped with the optical variable attenuator which can adjust the attenuation amount of the light to permeate | transmit. Interferometer characterized by the above-mentioned. The interferometer according to claim 3, wherein
After the reduction signal output means outputs the reduction signal, a second determination means for determining whether the amount of received light of the light receiving means is equal to or greater than a predetermined second threshold based on the light reception signal;
When the second determination unit determines that the amount of received light is equal to or greater than the second threshold value, a cancellation signal that instructs the dimming unit to cancel the reduction in the amount of light emitted from the light source. Signal output means,
The dimming unit cancels a reduction in the amount of light emitted from the light source when the cancellation signal is input. The interferometer according to any one of claims 1 to 4,
The reflector is a retroreflector that reflects incident light so that the incident light and the reflected light are parallel, and the incident light and the reflected light are point-symmetric with respect to the center. Yes,
The interferometer is a tracking laser interferometer that tracks the retroreflector so that a shift amount of light reflected by the retroreflector falls within a predetermined range.

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