JP2003194518A - Laser distance measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser distance measuring apparatus that has a small size and a light weight, can perform measurement to narrow spaces contactlessly, and can be used in gaseous and liquid environments. <P>SOLUTION: This laser distance measuring apparatus is provided with a measurement-side optical path which divides low-coherence laser light from a laser into measuring light and reference light, projects the measuring light upon an object to be measured by using an optical fiber, and leads reflected light from the object; a reference-side optical fiber which leads the reference light; and a light modulator which is provided at the front end of the reference-side optical path, reflects the reference light, and modulates the length of the reference-side optical path within the range from one wavelength to several hundred wavelengths of the laser light. This apparatus is also provided with a photodetector which detects output light produced by synthesizing reference-side reflected light reflected by the light modulator and led through the reference-side optical path and measurement-side reflected light and a data processor which outputs the information on the distance of the object to be measured by analyzing the presence/absence of interference and determining whether or not the lengths of the measurement- and reference-side optical paths are coincident with each other by correlating the signals obtained by means of the photodetector with the modulated signals of the modulator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser distance measuring device for transmitting a laser beam through an optical fiber to perform active non-contact distance measurement.

[0002]

2. Description of the Related Art Conventional non-contact distance measurement includes active type and passive type. The active type is a method of measuring a distance by projecting a signal such as light, sound, or radio wave from a measuring instrument toward an object to be measured and measuring reflection from the object to be measured. The passive method is a method of measuring the distance by reading the information projected from the object itself, and there is an image processing measurement by a camera.

Generally, the passive type based on visual information is easily affected by the environment such as the illuminance and the transparency of the atmosphere and has a drawback that the use environment is limited, and the application place and the application environment are limited. The active type provides a signal that relies on distance measurement by itself, so it has the advantage that it is not easily affected by the external environment.However, the conventional active distance measuring method has the drawback that the applicable range is limited by each measurement principle. is there.

For example, the eddy current method can measure only a comparatively short distance, cannot measure the distance of the closest point from the sensor and cannot be used if there is an obstacle in the vicinity, and the material of the object is limited. There are drawbacks such as In the case of ultrasonic distance measurement, there is a restriction on the tilt angle with respect to the object because the sound reflected from the wall surface is detected. Such directivity of measurement by eddy current or sound is poor, and distance measurement at points cannot be performed, so precise distance measurement is difficult.

As an active distance measuring method capable of precise distance measurement, distance measurement based on an optical principle using laser light is generally used. The conventional method is to measure by the principle of triangulation with a laser pointer and PSD (distance measuring sensor), to calculate the distance from the measurement of the round-trip time of pulsed laser light, or to use image processing by a laser scan light and a camera. There is a method of identifying the position and the distance. These generally require two optical devices on the laser emitting side and the light receiving side, and require a laser oscillator such as a semiconductor laser and an optical circuit such as a laser scanning mechanism and an autofocus mechanism. However, the size of the sensor part is large and it is difficult to miniaturize it, and it is difficult to apply it to the narrow part.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is compact and capable of measuring points on narrow spaces in a non-contact manner in air and liquid. It is an object of the present invention to provide a laser distance measuring device that can be used in any environment.

[0007]

According to a first aspect of the present invention, there is provided a laser distance measuring device, which comprises:
A beam splitter that receives the laser light from this laser device and divides it into a measurement laser light and a reference laser light, and a measurement in which the measurement laser light is guided by an optical fiber to an object to be measured and reflected by the object to be measured. A measurement side optical path that guides a reflected laser beam, a reference side optical path that guides the reference laser beam, and a reference side optical path that is provided at the tip of the reference side optical path and that reflects the reference laser beam, and the length of the reference side optical path is the laser beam. Optical modulator for modulating in the range from 1 wavelength to several hundred wavelengths, and output laser light obtained by combining the reference reflection laser light reflected by the optical modulator and guided by the reference side optical path and the measurement reflection laser light. Measurement is performed by performing a correlation process between the photodetector for detecting the signal and the signal obtained by the photodetector and the modulation signal of the optical modulator, and analyzing the presence or absence of interference. A configuration in which a data processing apparatus length and reference side optical path length of the optical path to output the information about the distance to whether the measurement object by performing judgment match.

According to the present invention, the laser oscillator, the beam splitter, the light receiving circuit, etc., which must be formed on the surface plate, are completely separated from the optical fiber of the sensor section, and the sensor section for projecting the laser is flexible. Since only the optical fiber and the objective lens are used, the measuring head can be downsized and can be applied to narrow spaces. Further, since the measuring head does not have a drive mechanism or the like, it is possible to easily provide underwater specifications.

According to a second aspect of the invention, there is provided a structure according to the first aspect of the invention. According to the present invention, it is possible to easily configure the optical path length on the reference side to be the same as that on the measurement side, and since the optical fiber on the reference light side can be used in a rolled state, even in a long-distance optical path. It can be realized without taking up space.

According to the invention of claim 3, in the invention of claim 2, the optical fiber of the reference side optical path and the optical fiber of the measurement side optical path are inserted in the same protective tube. According to the present invention, as in the second aspect of the present invention, it is possible to realize a long-distance optical path without taking a lot of space, and it is possible to measure a disturbance received by the optical fiber from the environment, a change in temperature and a change in expansion and contraction due to an external force. Since the two optical fibers on the side of the reference and the optical fiber on the side of the reference receive the same, it is possible to eliminate the need for compensation measures against these disturbances.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the optical modulator is a beam splitter including two half mirrors provided at right angles to the optical axis of the laser beam emitted from the laser device. Also, the reference laser light is configured to be transmitted through the optical fiber forming the measurement-side optical path. According to the present invention, a single optical fiber forms the measurement-side optical path and the reference-side optical path, so that a simple measuring device can be obtained.

According to a fifth aspect of the present invention, in the first aspect of the invention, the beam splitter is composed of two half mirrors obliquely provided on the optical axis of the laser beam emitted from the laser device. The reference laser light returned from is introduced into the optical fiber forming the measurement-side optical path.

According to a sixth aspect of the invention, an optical modulator includes a retro-reflector that reflects laser light, a speaker that drives the retro-reflector in the optical axis direction of the laser light, and a linear drive of the speaker in the optical axis direction. And a servo mechanism that operates.

According to the invention of claim 7, a piezo element is provided instead of the speaker. According to the invention of claim 8, the optical modulator comprises an optical fiber and a magnet and a coil for vibrating the optical fiber like a string.

According to a ninth aspect of the present invention, the optical fiber forming the optical path on the measurement side is provided along the articulated manipulator, and the tip of the optical fiber is arranged on the robot wrist.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser distance measuring device according to a first embodiment of the present invention will be described with reference to FIG. The laser distance measuring apparatus according to the first embodiment is a semiconductor laser oscillator 1 that generates laser light having a low coherence characteristic.
a and a laser device 1 including an amplitude modulation generator 7;
Data processing including a beam splitter 2 having a half mirror 2a, an optical modulator 3, an optical fiber 4, an objective side lens 5, an eyepiece side lens 6, a light receiving element 8, an input / output interface circuit 9 and a computer 10. The device 11 is a main component. Reference numeral 12 is an object to be measured.

Here, for convenience, the optical path from the laser device 1 to the beam splitter 2 is branched from the input side optical path 100 and the beam splitter 2 to and from the measuring object 12 via the optical fiber 4. The optical path to be measured is the measuring-side optical path 101, and the optical path that branches from the beam splitter 2 and reciprocates with the optical modulator 3 is the reference-side optical path 10.
2. The optical path from the beam splitter 2 to the light receiving element 8 is called the output side optical path 103. The optical path length of the measurement side optical path 101,
The optical path length of the reference side optical path 102 is almost the same.

The optical modulator 3 is an optical device that electrically or mechanically or optically oscillates the optical path length, and the details thereof will be described later. Here, for example, the optical modulator 3 from the beam splitter 2 side by a retro reflector is used. The laser light projected on is reflected and returned. A part of the laser light from the laser device 1, that is, the laser light from the input side optical path 100 passes through the half mirror 2a and goes straight to enter the measurement side optical path 101, and the remaining laser light is reflected by the surface of the half mirror 2a (normal In this case, the light is reflected by the reference side optical path 102.

Two types of laser light which enter the beam splitter 2 by traversing the measurement side optical path 101 and the reference side optical path 102 are:
Some of both laser beams go to the input side optical path 100,
The rest enters the output side optical path 103, enters the light receiving element 8 such as a photodiode, and is converted into an electric signal.

In the laser distance measuring apparatus according to the first embodiment of the present invention having such a structure, the light entering the light receiving element 8 is a composite wave of the light passing through some optical paths. When the lengths of the plurality of optical paths are substantially the same, mutual interference occurs and the amount of light increases or decreases, but this change is usually minute and difficult to detect. However, as shown in FIG. 2A, when one optical path length is sinusoidally oscillated at a constant frequency with an amplitude (wavelength from one wavelength to several hundred times) relatively close to the wavelength length of laser light, mutual interference occurs. Therefore, the output signal oscillates in a cycle that is an integral multiple of this frequency. This integer multiple component matches the integer of the value obtained by dividing the modulation distance of the optical path length by the wavelength of the laser light. The laser distance measuring device according to the present embodiment performs distance measurement based on this principle.

That is, the laser beam generated from the laser device 1 is split into two by the beam splitter 2, one goes straight and enters the measurement side optical path 101, and the eyepiece side lens 6, the optical fiber 4, and the objective side lens 5 are connected. After passing, it becomes parallel and is projected onto the measurement target 12. The reflected light of the center of the spot light is again the objective lens 5, the optical fiber 4,
It goes back through the eyepiece side lens 6 and returns to the beam splitter 2. On the other hand, the remaining laser light split by the beam splitter 2 is reflected by the half mirror 2a by 90 degrees, reaches the optical modulator 3 by the reference side optical path 102, is reflected there, and returns to the beam splitter 2 again. These returned laser beams pass through the beam splitter 2 and the light receiving element 8
Then, the change in the amount of light of the combined wave becomes an electric signal and is input to the computer 10.

Here, the optical modulator 3 in the reference side optical path 102
Then, the optical path is sinusoidally oscillated at a constant frequency with an amplitude relatively close to the wavelength of the laser light (wavelength from one wavelength to several hundred times).
At the same time, the optical modulator 3 is vibrated and moved back and forth.
Find a point where mutual interference occurs as shown in (a). At this time, the measurement side optical path 101 and the reference side optical path 102
Have the same length, and the distance to the measurement target 12 including the optical fiber 4 can be obtained by measuring the length of the reference-side optical path 102.

Next, a second embodiment of the present invention will be described with reference to FIG. The laser distance measuring device of this embodiment is the same as the laser distance measuring device of the first embodiment.
That is, the optical fiber 13 is inserted in the optical path of the reference side optical path 102 from the beam splitter 2 to the optical modulator 3. Before and after the optical fiber 13, lens systems 14 and 15 for focusing the laser light on the optical fiber 13 are provided.
To provide. Further, in this optical circuit, the measurement side optical path 10
The optical fiber 13 having an appropriate length is selected with respect to the optical fiber 4 so that the optical path length of 1 and the optical path length of the reference side optical path 102 are almost the same, and the optical fiber 13 is appropriately selected so as not to take up a space. It is rolled up.

The basic principle of measurement in the laser distance measuring apparatus according to the second embodiment is exactly the same as that in the first embodiment, but the optical fiber 13 is used as a part of the reference side optical path 102. Reference side optical path 102
It becomes easy to match the length of the optical path with the length of the optical path 101 on the measurement side, and since the optical fiber 13 can be freely bent, it does not take up a space, and influences the length of the optical fiber 4 on the optical path 101 on the measurement side. It is possible to configure the laser distance measuring device with a predetermined size and shape without receiving the laser beam.

Next, a third embodiment of the present invention will be described with reference to FIG. The laser distance measuring device of this embodiment passes the laser light returning from the optical modulator 3 to the optical fiber 16 as shown in FIG. The optical fiber 16 of the reference side optical path 102 is characterized by being integrated by the same protection tube 17 and having an integrated structure. In this optical circuit, the optical fiber 16 having an appropriate length is selected with respect to the optical fiber 4 so that the optical path length of the measurement-side optical path 101 and the optical path length of the reference-side optical path 102 are substantially the same.

In the laser distance measuring apparatus according to the third embodiment, the two optical fibers 4 and 16 are put together by the same protection tube 17, so that these optical fibers can be arranged in the same environment. Therefore, it becomes possible to reduce the distance measurement error caused by the change in the optical path length due to the change in the temperature of the optical fiber and the change in the elongation due to the external force, which cannot be ignored particularly in the case of the long optical fiber.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The laser distance measuring device according to the fourth embodiment is a beam splitter including a laser device 1 including a semiconductor laser oscillator 1a for generating laser light having a low coherence characteristic and an amplitude modulation generator 7, and a half mirror 2a. 2, an optical fiber 4, an objective lens 5, an eyepiece lens 6, a light receiving element 8, an input / output interface circuit 9 and a data processing device 11 including a computer 10. Reference numeral 12 is an object to be measured.

Further, two half mirrors 20 and 21 are positioned between the laser device 1 and the beam splitter 2 parallel to the optical axis, and the half mirror 2 on the laser device 1 side is positioned.
0 is configured to be linearly movable in the optical axis direction by the linear motor 22 and the linear guide 23.

In this configuration, the optical path that passes through the half mirrors 20 and 21 and travels straight and passes through the beam splitter 2 at the shortest distance becomes the measurement-side optical path 101. After passing through the half mirror 20 once, it is once reflected by the half mirror 21. Then, the beam returns to the half mirror 20, is reflected by the half mirror 20 again, and then passes through the half mirror 21 to enter the optical fiber 4 as the reference light side optical path 102.

In the laser distance measuring apparatus according to the fourth embodiment, one optical fiber 4 is used for the measuring side optical path 10.
1 and the reference side optical path 102 are formed. The mechanism will be described below.

The two half mirrors 20 and 21 arranged immediately in front of the laser device 1 act as an optical modulator. The path of the measurement-side optical path 101 is a path that goes straight through the two half mirrors 20 and 21. On the other hand, the reference side optical path 102
The first half mirror 20 goes straight, is reflected by the second half mirror 21 by 180 degrees, and is once returned to the first half mirror 20, is reflected there by 180 degrees, and is again returned by the half mirror 21. It is a pass through. The length of the measurement side optical path 101 and the length of the reference side optical path 102 are equal to each other when the distance difference between the half mirrors 20 and 21 with or without folding back is equal to the round-trip distance projected and returned from the optical fiber 4 to the measurement object 12. Are almost the same.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The laser distance measuring apparatus according to this embodiment includes a laser apparatus 1 including a semiconductor laser oscillator 1a for generating a laser beam having a low coherence characteristic and an amplitude modulation generator 7, two half mirrors 24 and 25, and a retro reflector. A light modulator 3 including 26, an optical fiber 4, an objective lens 5, an eyepiece lens 6, a light receiving element 8, a data processing device 11 including an input / output interface circuit 9 and a computer 10. As an element.

The retro-reflector 26 constitutes the optical modulator 3, and is capable of amplitude variation by servo driving in the optical axis direction and amplitude-modulating the optical path length by the configurations of FIGS. 7 and 8 described later. Has become. With such a configuration, a part of the laser light output from the laser device 1 is reflected by the first half mirror 24 by 90 degrees and reaches the retro reflector 26, and the remaining laser light is reflected by the half mirror 24 ,.
Go straight through 25 and reach the optical fiber 4. The laser light that has entered the retro reflector 26 is reflected by the retro reflector 2.
It is reflected by 6 and returned, and is reflected by the second half mirror 25 by 90 degrees and is incident on the optical fiber 4.

In the laser distance measuring apparatus according to the fifth embodiment, by providing the two half mirrors 24 and 25 acting as beam splitters, the laser on the reference side optical path 102 that has once passed through the optical modulator 3. It is possible to join the light with the laser light of the measurement side optical path 101, and the reference side optical path 102 also passes through the optical fiber 4, so that it is possible to obtain the same effect as the second embodiment with one optical fiber. .

In this configuration, as an operation for making the optical path length of the measurement-side optical path 101 and the optical path length of the reference-side optical path 102 coincide, the reference-side optical path 102 reflects light reflected from the end face (right end in FIG. 6) of the optical fiber 4. Is used as the optical path length of the laser beam that is once projected from the optical fiber 4 to the outside, is reflected from the measurement target 12 and returns, and the optical modulation is performed so that the optical path lengths of the two are almost the same. The difference of the reference side optical path 102 that bypasses the container 3 is adjusted.

FIG. 7 shows a concrete configuration example of the optical modulator 3 in the laser distance measuring devices of the first, second, third and fifth embodiments. That is, the retro reflector 27
A speaker 28, a linear drive servo mechanism 29,
It is composed of a linear guide 30. Here, the retro reflector 27 is an optical mirror that reflects laser light, and a half mirror may be applied.

With such a configuration, the speaker 28 changes the optical path length with an amplitude width several times to several hundred times the wavelength of the laser light.
The movement for making the total distance of the measurement side optical path 101 and the reference side distance 102 coincide with each other is performed by the linear drive servo mechanism 2
9. In both cases, the retro reflector 27 fluctuates and the optical path length of the reference side optical path 102 changes.

Another configuration example of the optical modulator 3 is shown in FIG. That is, it is composed of a retro reflector 27, a piezo element 31, a linear drive servo mechanism 29, and a linear guide 30.

In the optical modulator 3 having this structure, the piezo element 31 causes an optical path length change having an amplitude width several times to several hundred times the wavelength of the laser light. The linear drive servo mechanism 29 performs movement to match the total distance of the measurement-side optical path 101 and the reference-side distance 102. In either case, the retro-reflector 27 is displaced and the optical path length of the reference-side optical path 102 changes. To do.

The function of the optical modulator 3 can also be realized by the configuration shown in FIG. That is, a part of the optical fiber 32 of the reference side optical path 102 is connected to the pin joint 3
3a and 33b are stretched in a straight line to give a tension, a magnet 34 is attached to a portion which becomes a straight line by this tension, and an electromagnetic coil 35 is arranged in the vicinity of the magnet 34. With such a configuration, when the electromagnetic coil 35 is excited, a Lorentz force is applied to the magnet 34, causing the optical fiber 32 to vibrate like a guitar string, thus vibrating the optical path length. A lens 36 and a linear drive servo mechanism 37 are provided on the input side of the optical fiber 32 so that the lens 36 can be moved in the optical axis direction.

The optical modulator 3 utilizes the elasticity of the optical fiber 32 and vibrates the optical fiber 32 like a string to change the optical path length of an amplitude width corresponding to several times to several hundred times the wavelength of the laser light. Generate. This action is realized by causing an alternating current to flow through the electromagnetic coil 35 and generating a Lorentz force in the magnet 34 attached to the optical fiber 32. The movement for matching the total distance of the measurement-side optical path 101 and the reference-side distance 102 is realized by moving the entrance of the optical fiber 32 together with the lens 36 on the eyepiece side by a linear drive servo mechanism 37.

FIG. 10 shows a laser distance measuring apparatus according to the sixth embodiment of the present invention. Articulated manipulator 40
The optical fiber 41 is built in and the tip of the optical fiber 41 is arranged on the robot wrist 42. According to this embodiment, it is possible to provide a precise rangefinder on an industrial site or in a bad environment.

The laser distance measuring apparatus according to each of the above-described embodiments can be applied not only in the air but also in water or in vacuum as long as the transparency is relatively high. Since the optical fiber is flexible and thin,
It can be applied to the distance measurement of an object inside a winding thin tube. Furthermore, by using a radiation-resistant optical fiber made of pure quartz glass, it can be applied to underwater distance measurement of reactor internals inside the pressure vessel of a nuclear power plant and distance measurement in outer space. Besides, it can be applied to the distance measurement inside the blast furnace by using an optical fiber having high heat resistance.

[0044]

According to the present invention, there is provided a laser distance measuring device which is compact and can be used for measuring points on narrow spaces without contact, and can be used in both air and liquid environments. Can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a laser distance measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a mutual interference relationship between laser light in a measurement-side optical path and laser light in a reference-side optical path in the laser distance measuring device according to the first embodiment of the present invention, in which (a) is a modulation signal. , (B) is an interference signal, and (c) is a waveform diagram showing a signal after square-law detection.

FIG. 3 is a diagram showing a configuration of a laser distance measuring device according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a laser distance measuring device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a laser distance measuring device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a laser distance measuring device according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing an example of an optical modulator in the laser distance measuring devices according to the first, second, third, and fifth embodiments.

FIG. 8 is a diagram showing another example of the optical modulator in the laser distance measuring devices according to the first, second, third, and fifth embodiments.

FIG. 9 is a diagram showing still another example of the optical modulator in the laser distance measuring devices according to the second and third embodiments.

FIG. 10 is a diagram showing a laser distance measuring device according to a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser device, 1a ... Semiconductor laser oscillator, 2 ... Beam splitter, 2a ... Half mirror, 3 ... Optical modulator, 4
... optical fiber, 5 objective lens, 6 eyepiece lens, 7 amplitude modulation generator, 8 light receiving element, 9 input / output interface circuit, 10 computer, 11 data processing device, 12 measurement object, 13 ... Optical fiber, 14
… Lens system, 15… Lens system, 16… Optical fiber, 1
7 ... Protective tube, 20 ... Half mirror, 21 ... Half mirror, 22 ... Linear motor, 23 ... Linear guide, 24 ...
Half mirror, 25 ... Half mirror, 26 ... Retro reflector, 27 ... Retro reflector, 28 ... Speaker, 2
9 ... Linear drive servo mechanism, 30 ... Linear guide, 3
1 ... Piezo element, 33a, 33b ... Pin joint, 3
4 ... Magnet, 35 ... Electromagnetic coil, 36 ... Linear guide, 3
7 ... Linear drive servo mechanism, 40 ... Multi-joint manipulator, 41 ... Optical fiber, 42 ... Robot wrist, 10
0 ... Input side optical path, 101 ... Measurement side optical path, 102 ... Reference side optical path, 103 ... Output side optical path.

Continued front page    (72) Inventor Satoshi Okada             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Yasuhiro Yuguchi             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office F term (reference) 2F065 AA01 AA06 AA20 BB01 BB25                       DD02 FF52 FF61 GG06 GG22                       HH04 JJ01 JJ18 LL00 LL02                       LL16 LL37 LL62 MM16 NN08                       PP25 QQ25 QQ28 RR10 UU07

Claims (9)

[Claims] 1. A laser device for generating a laser beam of low coherence, a beam splitter for receiving the laser beam from the laser device and splitting the laser beam for measurement into a laser beam for reference, and an optical fiber for the laser beam for measurement. A measurement-side optical path that guides the measurement reflected laser light reflected by the measurement target by irradiating the measurement target by irradiating the measurement target, a reference-side optical path that guides the reference laser light, and the reference provided at the tip of the reference-side optical path. An optical modulator that reflects the laser light for use and modulates the length of the reference-side optical path in the range of one wavelength to several hundreds of wavelengths of the laser light, and is reflected by the optical modulator and guided by the reference-side optical path. A photodetector for detecting an output laser beam obtained by combining the reference reflected laser beam and the measurement reflected laser beam, a signal obtained by the photodetector, and a change of the optical modulator. Correlation processing with the control signal is performed, and the presence or absence of interference is analyzed to determine whether the length of the measurement-side optical path and the reference-side optical path match, and output information about the distance to the measurement target. A laser distance measuring device, comprising: 2. The laser distance measuring device according to claim 1, wherein the optical path on the reference side includes an optical fiber. 3. The laser distance measuring device according to claim 2, wherein the optical fiber of the reference side optical path and the optical fiber of the measuring side optical path are inserted into the same protective tube. 4. The optical modulator is composed of two half mirrors provided at right angles to the optical axis of the laser light emitted from the laser device and also serves as a beam splitter, and the reference laser light is used as a measurement side optical path. The laser distance measuring device according to claim 1, wherein the laser distance measuring device is transmitted through an optical fiber that forms a laser beam. 5. The beam splitter is composed of two half mirrors obliquely provided on the optical axis of the laser light emitted from the laser device, and the reference laser light returning from the reference optical path is the measurement optical path. The laser distance measuring device according to claim 1, wherein the laser distance measuring device is introduced into an optical fiber that forms a laser. 6. The optical modulator comprises a retro-reflector that reflects laser light, a speaker that drives the retro-reflector in the optical axis direction of the laser light, and a servo mechanism that linearly drives the speaker in the optical axis direction. The laser distance measuring device according to claim 15, further comprising: 7. The laser distance measuring device according to claim 6, further comprising a piezo element instead of the speaker. 8. The laser distance measuring device according to claim 2, wherein the optical modulator includes an optical fiber and a magnet and a coil for vibrating the optical fiber like a string. 9. The laser distance measuring apparatus according to claim 1, wherein the optical fiber forming the optical path on the measurement side is provided along the articulated manipulator, and the tip of the optical fiber is arranged on the wrist of the robot.