JP2014059247A - Distance measurement method and device - Google Patents

Abstract

An object of the present invention is to effectively remove spontaneously emitted light from the output light of an optical amplifier and improve the gain and SN with respect to a signal light pulse.
The present invention relates to a light source that generates pulsed light, an optical amplifier that amplifies light generated from the light source and reflected from a measurement target, and a time during which the pulse passes among the amplified light. Provided is a distance measuring device including an optical switch that selectively transmits light.
[Selection] Figure 1

Description

  The present invention relates to a distance measurement method and a distance measurement device.

  The distance measuring device of Patent Document 1 uses a femtosecond mode-locked pulse laser device.

  The multistage optical amplifying device of Patent Document 2 effectively removes spontaneously emitted light from the output light of each optical amplifier by driving the optical switch in synchronization with the timing of the signal light pulse, and gain for the signal light pulse. And a multi-stage optical amplifier capable of improving the SN ratio.

JP 2006-184181 A Japanese Patent Laid-Open No. 2-5912

  The distance measuring device of Patent Document 1 is assumed to be a reflective prism, retroreflective plate, or bright natural object surface as a measurement target, and is like a medium-sized product (turbine, railway vehicle, escalator, automobile, airplane, etc.) If the reflected light is weak, such as a machined surface, the distance cannot be measured accurately.

  In the multistage optical amplifying device of Patent Document 2, in order to match the timing of driving the optical switch with the timing of transmission of the signal light pulse, a part of the signal light pulse is taken out by a demultiplexer and photoelectrically converted by a photodetector to generate a timing signal. Is generated. However, if the signal light pulse is weak and the position cannot be determined accurately, it is difficult to set the timing for the signal light pulse.

  In view of the above problems, an object of the present invention is to effectively remove spontaneously emitted light from the output light of an optical amplifier and improve the gain and SN with respect to a signal light pulse.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  Specifically, the present invention relates to a light source that generates pulsed light, an optical amplifier that amplifies the light generated from the light source and reflected from the measurement target, and the time during which the pulse passes through the amplified light. And a distance measuring device including an optical switch that selectively transmits light.

  In another aspect, the present invention generates pulsed light, irradiates the measurement target with the generated light, amplifies the reflected light, and outputs the light at the time that the pulse passes among the amplified light. Provided is a distance measuring method characterized by selectively transmitting through an optical switch and measuring the distance to a measurement object using information of the transmitted light.

  According to the present invention, spontaneous emission light can be effectively removed from the output light of the optical amplifier, and the gain and SN with respect to the signal light pulse can be improved.

FIG. 2 is an apparatus configuration diagram for driving an optical switch based on position information of a focus stage using the optical comb in the first embodiment as a light source. FIG. 3 is an example of an optical switch in the first embodiment. It is a figure explaining the flow of the signal light pulse in a 1st Example. It is a device block diagram which changes the amplification factor of an optical amplifier based on the positional information on a focus stage, using the optical comb in a 2nd Example as a light source. It is an apparatus block diagram which drives an optical switch based on the phase information detected by a phase meter using the optical comb in the third embodiment as a light source. Device configuration diagram in which an optical comb in the fourth embodiment is used as a light source, optical beat down is performed by an optical waveguide intensity modulator, and a high-frequency signal input to the optical waveguide intensity modulator is turned on and off by a switch based on position information of the focus stage It is. It is an operation | movement figure of the optical waveguide intensity | strength modulator in a 4th Example. It is a figure explaining the flow of the signal light pulse in a 4th Example. It is a figure explaining the new effect which suppresses a back surface reflection component in the 4th example. FIG. 10 is an apparatus configuration diagram in which an optical comb in a fifth embodiment is used as a light source, optical beat down is performed by an optical waveguide intensity modulator, and an amplification factor of an optical amplifier is changed based on position information of a focus stage. FIG. 10 is an apparatus configuration diagram in which an optical comb in a sixth embodiment is used as a light source, optical beat down is performed by an optical waveguide intensity modulator, and an optical switch is turned on / off based on position information of a focus stage. It is an apparatus block diagram which turns on and off the high frequency signal input into an optical waveguide intensity | strength modulator based on the phase information detected with a phase meter by using the optical comb in a 7th Example as a light source. FIG. 10 is a configuration diagram of a three-dimensional distance measuring device equipped with the distance measuring optical system mechanism described in the first to seventh embodiments. It is a whole figure of the three-dimensional distance measuring apparatus in an 8th Example. It is the conventional apparatus block diagram using an optical comb. It is explanatory drawing of the method of suppressing an ASE component with respect to the conventional method. It is explanatory drawing of the method of suppressing an ASE component with respect to the conventional method.

  Hereinafter, examples will be described with reference to the drawings.

  FIG. 15 shows a high-precision distance measuring device using a conventional optical comb. The optical comb 101 is used as a light source. The light is irradiated into the space by the fiber collimator 104, and a part of the beam is divided by the beam splitter 105, detected by the light receiver 1501, and used as a reference signal. The main part of the beam is irradiated onto the measuring object 1505, the reflected light returns to the main body again, and is detected by the light receiver 1503 to become a probe signal. A frequency component used for distance measurement is selected from a number of frequency components included in the probe signal by bandpass filters 1502 and 1504, and a phase difference from the reference signal is measured by a phase meter 118 to obtain distance information 119. This device assumes a reflecting prism, retroreflective plate, or bright natural object surface as a measurement target, and is a machined surface such as medium-sized or large-sized products (turbine, railway vehicle, escalator, automobile, airplane, etc.) Thus, there is a problem that the distance cannot be measured accurately when the reflected light is weak.

  An optical amplifier is used as an example for detecting weak light. However, since ASE (spontaneously emitted light) is generated, an upper limit is imposed on the amplification factor (gain). Therefore, a method of suppressing the ASE component is taken. FIG. 16 shows a conventional method for suppressing the ASE component.

  One is a method of suppressing with frequency components. The ASE component in FIG. 16B is generated with a wider frequency band than the frequency band of the light source in FIG. Therefore, the ASE component can be suppressed by using a filter that cuts frequency components other than the light source shown in FIG.

  The other is a method of suppressing with polarized light. By using the polarizer of FIG. 16D, the ASE component can be suppressed by passing the polarization component of the signal light whose polarization direction matches that of the polarizer and cutting the random polarization component of the ASE. .

  Furthermore, there is a method of suppressing with time. FIG. 17 shows a method of suppressing by time. It is possible to suppress the ASE component by transmitting the signal light pulse amplified by the optical amplifier 1701 of FIG. 17A in accordance with the time when the pulse passes by the optical switch 1702 and blocking at other times. Become. A part of the signal light pulse input to the optical amplifier is extracted by a demultiplexer, and photoelectrically converted by a photodetector to be a timing signal, thereby matching the timing of driving the optical switch. By inputting the signal light pulse of FIG. 17B to the optical amplifier, output light in which spontaneous emission light is superimposed on the amplified signal light pulse as shown in FIG. Here, as shown in FIG. 17 (e), an optical switch having a characteristic of transmitting the signal light pulse in accordance with the passing time and blocking at other times as shown in FIG. 17 (d) is used. Unnecessary ASE components can be suppressed. However, in order to generate the timing signal, it is necessary to detect a part of the signal light pulse. However, when the signal light pulse is weak, there is a problem that the timing signal cannot be generated.

  In view of the problems of the distance measuring apparatus and the optical amplification method shown in FIGS. 15 and 17, the distance measuring method using the developed optical comb and optical amplifier in the first embodiment will be described with reference to FIG.

  FIG. 1 is an example of a configuration diagram of a distance measuring apparatus according to the present embodiment. The optical comb irradiated from the optical comb generator 101 whose repetition frequency is controlled to be constant by the oscillator 102 is irradiated into the space by the fiber collimator 104 and enters the polarization beam splitter 105. A part of the light is collected by the fiber collimator 110 and converted into an electric signal by the light receiver 111, and a main part passes through the λ / 4 plate 106 and is focused on the measurement object 109 by the focus lens 107. The reflected light from the object is collected again by the focus lens 107, passes through the λ / 4 plate 106, reflected by the polarization beam splitter 105, collected by the fiber collimator 113, amplified by the optical amplifier 114, The light passes through the optical switch 115, is converted into an electric signal by the light receiver 116, and only the frequency component used for distance measurement is extracted by the filter 117 and input as a measurement signal of the phase meter 119. Only the frequency component used for distance measurement is extracted from the electrical signal output from the light receiver 111 by the filter 112 and input as a reference signal for the phase meter 118. The phase meter 118 is a device that calculates the phase difference between two input signals. The phase meter 118 calculates the phase of the measurement signal with respect to the reference signal, and the distance calculation circuit 119 calculates the distance from the phase information. By determining the approximate distance to the object from the position information of the focus stage 108 equipped with the focus lens 107, the timing at which the signal light pulse passes through the optical switch can be known. The phase of the sine wave signal output from the oscillator 102 that controls the repetition frequency of the optical comb is phase-shifted in accordance with the timing at which the signal light pulse passes through the optical switch by the phase shifter 120, and converted into a rectangular wave by the comparator 121. By inputting to the optical switch 115, it is possible to transmit only the signal light pulse, suppress the ASE component, and improve the gain and SN with respect to the signal light pulse.

  As one configuration example, a phase shifter may be unnecessary by determining the phase when the sine wave is converted into the rectangular wave by the comparator 121 using the information of the focus stage.

  Further, as one configuration example, a part of the light emitted from the optical comb instead of the oscillator 102 may be branched out by a fiber coupler and photoelectrically converted by a light receiver. In this case, since a pulse waveform is formed, the comparator is unnecessary.

  FIG. 2 shows an example of an optical switch. A Mach-Zehnder type optical waveguide intensity modulator is shown, and can be used as an optical switch by inputting a rectangular wave as a modulated electric signal. An example of the optical waveguide intensity modulator is an LN modulator. A semiconductor laser type optical switch may be used.

  Fig. 3 shows the flow of signal light pulses. The light emitted from the optical comb 101 is a pulse train arranged at equal intervals. Light scattered from the measurement object 109 and collected by the fiber collimator 113 becomes a weak signal. The signal amplified by the optical amplifier includes an ASE (spontaneously emitted light) component in addition to the signal light pulse. Based on the position information of the focus stage 108, the phase of the sine wave signal of the oscillator 102 is shifted by the phase shifter 120, converted into a rectangular wave by the comparator 121, and input to the optical switch 115. Thereby, the optical switch 115 can be turned on and off at the timing when the signal light pulse passes through the optical switch, and the ASE component can be suppressed.

  As described above, according to the present embodiment, the optical switch 115 can transmit only the signal light pulse to suppress the ASE component and improve the gain and SN with respect to the signal light pulse. In addition, by determining the approximate distance to the object from the position information of the focus stage 108, it is possible to know the timing at which the signal light pulse passes through the optical switch, and to match the timing at which the signal light pulse passes through the optical switch. Therefore, it is possible to suppress the ASE component and improve the gain and SN with respect to the signal light pulse.

  A second embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the optical amplifier has the characteristics of an optical switch. As in the first embodiment, the phase of the sine wave signal from the oscillator 102 is shifted by the phase shifter 120 in accordance with the timing when the signal light pulse passes through the optical amplifier 114 based on the position information of the focus stage 108. The signal is converted into a rectangular wave signal by the comparator 121 and input to the current controller of the excitation laser of the optical amplifier. The signal light pulse is amplified by increasing the pump laser current at the timing when the signal light pulse passes, and the pump laser current is decreased at other times and the signal light pulse is not amplified. It is possible to have both an amplification function and an optical switch function. According to the present embodiment, the optical switch shown in the first embodiment is not necessary, and the cost can be reduced.

  A third embodiment of the present invention will be described with reference to FIG.

  In this embodiment, it is possible to know the timing at which the signal light pulse passes through the optical switch by determining the approximate distance to the object based on the phase information detected by the phase meter 118. By using a lock-in amplifier or the like as the phase meter 118, it becomes possible to know the phase information, that is, the position information of the signal light pulse buried in the noise. Here, the lock-in amplifier is a device for accurately obtaining the phase of two input signals. The phase information is input to the phase shifter 120, and the phase of the sine wave signal output from the oscillator 102 that controls the repetition frequency of the optical comb is adjusted by the phase shifter 120 in accordance with the timing at which the signal light pulse passes through the optical switch. By converting to a rectangular wave and inputting to the optical switch, it is possible to transmit only the signal light pulse, suppress the ASE component, and improve the gain and SN for the signal light pulse. According to the present embodiment, the position information of the focus stage shown in the first embodiment is not necessary, and the information amount can be reduced.

  A fourth embodiment of the present invention will be described with reference to FIGS. 6 (a) and 6 (b).

  FIG. 6A is an example of a configuration diagram of the distance measuring apparatus according to the present embodiment. The optical comb irradiated from the optical comb generator 101 is irradiated into the space by the fiber collimator 104 and enters the polarization beam splitter 105. A part of the light is collected by the fiber collimator 110, enters the optical waveguide intensity modulator 605, and a main part passes through the λ / 4 plate 106 and is focused on the measurement object 109 by the focus lens 107. The reflected light from the object passes through the λ / 4 plate 106 again, is reflected by the polarization beam splitter 105, is collected by the fiber collimator 113, is amplified by the optical amplifier 114, and enters the optical waveguide intensity modulator 606. . The oscillator 603 generates a high-frequency modulation signal, is branched into two by the power divider 604, and is input to the optical waveguide intensity modulators 605 and 606, respectively. The light that has passed through the optical waveguide intensity modulator 605 is converted into an electrical signal by the light receiver 111, and only the frequency component used for distance measurement is extracted by the filter 112 and input as a reference signal for the phase meter 118. Similarly, the light that has passed through the optical waveguide intensity modulator 606 is converted into an electric signal by the light receiver 116, and only the frequency component used for distance measurement is extracted by the filter 117 and input as a measurement signal of the phase meter 118. The phase is calculated by the phase meter 118 and the distance is calculated by the distance calculation circuit 119. The reference signal 601 is branched by the power divider 602 and used to synchronize the oscillations of the oscillator 603 and the oscillator 102.

  FIG. 6B shows the principle of optical beat-down of an optical comb using an optical waveguide intensity modulator. As an example, if the repetition frequency of the optical comb is 10.0001 MHz, the spectrum exists at intervals of 10.0001 MHz on the frequency. The frequency interval of a spectrum 10000 lines away from a certain spectrum is 100.001 GHz. Consider the case where this beat signal is used for distance measurement. For example, let us consider a case where frequency modulation is performed on a signal light pulse by an optical waveguide intensity modulator 605 or 606 using a high-frequency modulation signal from an oscillator 603, and optical beat down is performed using a primary sideband component. For example, when 100 GHz is given as the oscillation frequency of the oscillator 603, a frequency of 1 MHz is obtained from a difference between a −1st order frequency (11.0001 GHz) and a first spectrum frequency (10.0001 GHz) of a spectrum frequency (100.0110001 GHz) away from 10,000. Ingredients can be generated. By extracting only 1 MHz used for distance measurement by the filter 117, it is possible to beat down to 1 MHz and detect it by the light receiver 116. Considering the case of optical beat-down using the second order component, 50 GHz is given as the oscillation frequency of the oscillator 603, and the second order frequency (11.0001 GHz) of the spectrum frequency (100.0110001 GHz) separated by 10,000 is 1 A frequency component of 1 MHz can be generated from the difference in the frequency (10.0001 GHz) of the main spectrum. By extracting only 1 MHz used for distance measurement by the filter 117, it is possible to beat down to 1 MHz and detect it by the light receiver 116. Similarly, considering the case of optical beat-down using an n-order component, the oscillation frequency of the oscillator is given as 100 / n GHz, and the −n-order frequency (11.0001) of the spectrum frequency (100.0110001 GHz) separated by 10,000 lines. 1 GHz frequency component can be generated from the difference between the frequency of the first spectrum and the frequency of the first spectrum (10.0001 GHz). By extracting only 1 MHz used for distance measurement by the filter 117, it is possible to beat down to 1 MHz and detect it by the light receiver 116. Further, if the optical beat down can be performed using higher-order sideband components, the oscillation frequency of the oscillator can be suppressed to a low frequency.

  In this embodiment, it is possible to know the timing at which the signal light pulse passes through the optical waveguide intensity modulator by determining the approximate distance to the object from the position information of the focus stage 108 on which the focus lens 107 is mounted. The phase of the sine wave signal output from the oscillator 102 that controls the repetition frequency of the optical comb is adjusted by the phase shifter 120 in accordance with the timing at which the signal light pulse passes through the optical waveguide intensity modulator, and converted into a rectangular wave by the comparator 121, The signal 606 is input to the switch 607, and the high-frequency signal from the oscillator 603 is switched between transmission and cutoff so that only the signal light pulse is transmitted and beat-down, and the ASE component is suppressed to reduce the gain and SN of the signal light pulse. Can be improved.

  FIG. 7 illustrates a method of transmitting only the signal light pulse and optically beating down using an optical amplifier. As shown in FIG. 7A, the operating point of the optical waveguide modulator is set to a bias voltage position where interference light cancels out. When a modulation signal is input, the light intensity changes around the operating point, and modulated light having a frequency twice that of the given modulation signal is generated. In other words, when a modulation signal is given, optical modulation for optical beat-down occurs, and when no modulation signal is given, it functions as an optical switch that blocks light.

  FIG. 7B shows the operation. By inputting a signal light pulse containing an ASE component and inputting a high-frequency electrical signal generated in synchronization with the signal light pulse, the signal light pulse can be transmitted and beat down to suppress the ASE component. .

  FIG. 8 shows the flow of signal light pulses. The light emitted from the optical comb becomes a pulse train arranged at equal intervals. Light scattered from the measurement target and collected by the fiber collimator 113 becomes a weak signal. The signal amplified by the optical amplifier includes an ASE (spontaneously emitted light) component in addition to the signal light pulse. Based on the position information of the focus stage 108, the phase of the sine wave signal of the oscillator 102 is shifted by the phase shifter 120, and a switch is made for a high-frequency electrical signal output from the oscillator 603 at the timing when the signal light pulse passes through the optical waveguide intensity modulator. The ASE component can be suppressed by turning on and off and inputting to the optical waveguide intensity modulator 606.

  FIG. 9 illustrates a new effect of suppressing the back surface reflection component. The measurement light irradiated from the fiber collimator 104 passes through the wave plate 106 and the focus lens 107 and is irradiated to the measurement object 109. In addition to the object to be measured, back reflection components from the wave plate 106 and the focus lens 107 are detected. Since the reflected light from the object to be measured is weak light, a slight amount of back surface reflection component may cause an error in phase measurement. In the configuration of FIG. 9, since the signal light pulse is transmitted and blocked according to the distance to the measurement object, the back surface reflection component generated at a short distance after irradiation is different in timing from the signal light pulse and can be blocked. It is. As a result, the back reflection component can be suppressed and the phase of the weak signal light can be accurately obtained. This effect can also be obtained in the configurations of other embodiments. According to the present embodiment, it is possible to detect a phase of a signal having a higher frequency than that of the first embodiment, and it is possible to perform distance measurement with high accuracy.

  A fifth embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the optical amplifier has the characteristics of an optical switch. As in the fourth embodiment, the phase of the sine wave signal from the oscillator 102 is shifted by the phase shifter 120 in accordance with the timing at which the signal light pulse passes through the optical amplifier 114 based on the position information of the focus stage 108. The signal is converted into a rectangular wave signal by the comparator 121 and input to the current controller of the excitation laser of the optical amplifier 114. Amplification is performed by increasing the pumping laser current at the timing when the signal light pulse passes, and by reducing the pumping laser current at other times and not amplifying it, both the optical amplification function and the optical switch function are achieved. It becomes possible to have a function. According to the present embodiment, it is possible to detect a phase of a signal having a higher frequency than that of the first embodiment, and it is possible to perform distance measurement with high accuracy. Further, the switch 607 is not required for the fourth embodiment, and the cost can be reduced.

  A sixth embodiment of the present invention will be described with reference to FIG.

  In this embodiment, an optical switch 1101 is newly added. As in the fourth embodiment, the phase of the sine wave signal from the oscillator 102 is shifted by the phase shifter 120 in accordance with the timing at which the signal light pulse passes through the optical amplifier 114 based on the position information of the focus stage 108. The signal is converted into a rectangular wave signal by the comparator 121, and only the signal light pulse is transmitted by turning on and off the optical switch at the timing when the signal light pulse passes to suppress the ASE component, and the gain and SN for the signal light pulse are reduced. It becomes possible to improve. According to the present embodiment, it is possible to detect a phase of a signal having a higher frequency than that of the first embodiment, and it is possible to perform distance measurement with high accuracy.

  A seventh embodiment of the present invention will be described with reference to FIG.

  In this embodiment, it is possible to know the timing at which the signal light pulse passes through the optical switch by determining the approximate distance to the object based on the phase information detected by the phase meter 118. By using a lock-in amplifier or the like as the phase meter 118, it becomes possible to know the phase information, that is, the position information of the signal light pulse buried in the noise. The phase information is input to the phase shifter 120, and the phase of the sine wave signal output from the oscillator 102 that controls the repetition frequency of the optical comb is adjusted by the phase shifter 120 to the timing at which the signal light pulse passes through the optical waveguide intensity modulator. The ASE component can be suppressed by converting it into a rectangular wave by the comparator 121, turning on and off the switch for the high-frequency electric signal output from the oscillator 603, and inputting it to the optical waveguide intensity modulator 606. According to the present embodiment, it is possible to detect a phase of a signal having a higher frequency than that of the first embodiment, and it is possible to perform distance measurement with high accuracy. Further, the position information of the focus stage becomes unnecessary, and the amount of information can be reduced.

  An eighth embodiment of the present invention will be described with reference to FIG.

  In this embodiment, an example of a three-dimensional distance measuring device equipped with the distance measuring optical system mechanism described in the first to seventh embodiments will be described. FIG. 13 is an example of an apparatus configuration diagram of this embodiment. The light emitted from the focus lens 107 can be three-dimensionally scanned by the galvano scanner 1301, and three-dimensional shape measurement is possible. As the beam scanning means, scanning by a polygon mirror or scanning means for rotating a shaft on which the mirror is mounted by a direct drive motor may be used. FIG. 14 shows an overall view of the three-dimensional distance measuring apparatus. It includes a distance measurement unit 1403, a focus stage 108, and a galvano scanner 1301, a power supply unit 1402 for driving them, and a GUI unit 1403 for controlling the apparatus and displaying the distance measurement results.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

101 ... Hikari Com,
102 ... Oscillator,
103 ... Power divider,
104: Fiber collimator,
105: Polarizing beam splitter,
106 ... λ / 4 plate,
107: focus lens 108: focus lens drive stage,
109 ... measurement object,
110: Fiber collimator,
111 ... receiver,
112 ... filter,
113 ... Fiber collimator 114 ... Optical amplifier,
115: optical switch,
116: light receiver,
117 ... filter,
118 ... Phase meter,
119: Distance calculation circuit,
120: Phase shifter,
121 ... Comparator,
601 ... Standard signal,
602 ... Power divider,
603 ... an oscillator,
604 ... Power divider,
605: Light intensity modulator,
606: Light intensity modulator,
607 ... switch,
1101 ... Optical switch,
1301 ... Galvano scanner,
1401 ... Distance measuring unit,
1402 ... power supply,
1403 ... display screen,
1501 ... detector,
1502 ... filter,
1503 ... detector,
1504 ... filter,
1505 ... measurement object,
1701... Optical amplifier,
1702 ... Optical switch,
1703: optical amplifier,
1704: optical switch,
1705 ... Drive device,
1706 ... drive device,

Claims (12)

A light source that generates pulsed light;
An optical amplifier that amplifies the light generated from the light source and reflected from the measurement object;
A distance measuring device comprising: an optical switch that selectively transmits light in a time during which a pulse passes among amplified light.   2. The distance measuring device according to claim 1, wherein the light source has a transmission frequency control mechanism for controlling a repetition frequency.   The distance measuring apparatus according to claim 1, wherein the optical switch changes a timing of transmitting light according to distance information to the measurement target.   The distance measuring apparatus according to claim 1, wherein the optical switch changes a timing of transmitting light according to phase information of a phase meter to which light transmitted through the optical switch is input.   2. The distance measuring device according to claim 1, wherein the optical switch is an optical waveguide intensity modulator that selectively transmits the light in the time during which the pulse passes among the amplified light by optical beat-down.   The distance measuring apparatus according to claim 1, further comprising a GUI screen that displays a measurement result. A light source that generates pulsed light;
An excitation laser that changes the intensity of the light generated from the light source by changing the current and reflected from the measurement target, and selectively transmits the amplified light at the time when the pulse passes. Distance measuring device. A light source that generates pulsed light;
Light that is generated from the light source by changing the current, changes the intensity of the light reflected from the object to be measured, and selectively transmits the light at the time when the pulse passes among the amplified light by optical beat-down. A distance measuring device comprising a waveguide intensity modulator. Generate pulsed light,
Amplifies the reflected light by irradiating the measurement object with the generated light,
The light at the time when the pulse passes among the amplified light is selectively transmitted by the optical switch,
A distance measurement method characterized by measuring a distance to a measurement object using information of transmitted light.   The distance measuring method according to claim 9, wherein a timing of transmitting light is changed according to distance information to the measurement target.   The distance measuring method according to claim 10, wherein the light transmission timing is changed according to phase information of the transmitted light.   The distance measuring method according to claim 10, wherein the amplified light is beat down.

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