JP4707142B2 - Light wave distance meter - Google Patents

Description

  The present invention transmits light modulated by a standard signal to a measurement optical path and a reference optical path, and based on the phase of the reflected light reflected by the target on the measurement optical path and the phase of the light from the reference optical path. It is related with the light wave rangefinder which can ask for the distance to.

  As an optical distance meter, for example, a reflected light by a distance measuring light (laser beam) irradiated toward a target or a reference light from a reference light path is received, and a phase difference between the phase of the reflected light and the phase of the reference light is detected. Seeking distance. In this type of optical wave distance meter, the reference light is obtained by photoelectric conversion when the distance to the target is obtained based on the phase difference between the phase of the signal obtained by photoelectric conversion of the reflected light and the phase of the reference signal. Based on the phase difference between the phase of the received signal and the phase of the reference signal, the distance to the target is obtained, and the difference between the two values can be calculated to eliminate errors caused by the light emitting element and the light receiving element. (See Patent Document 1).

JP 2002-323563 A

  In the prior art, two types of laser diodes that emit laser beams having different wavelengths are used as light sources. The phase difference between the measurement light and the reference light signal is obtained by switching the measurement light with a shutter. In addition, the signal obtained by photoelectric conversion of the reflected light reflected and returned from the target as the ranging light is transmitted and the signal obtained by photoelectric conversion of the reference light are alternately input to the CPU. In the CPU, a process for calculating the light to the target based on the phase difference between the phase of the signal obtained by photoelectrically converting the reflected light and the phase of the standard signal, and the signal obtained by photoelectrically converting the reference light Since the process of calculating the distance to the target is alternately performed based on the phase difference between the phase of the reference signal and the phase of the reference signal, the distance to the target is finally obtained based on the calculation result of each process. It is not enough to shorten the measurement time.

  That is, the process of calculating the distance to the target based on the phase difference between the phase of the signal obtained by photoelectric conversion of the reflected light and the phase of the reference signal, and the phase of the signal obtained by photoelectric conversion of the reference light Since the processing to calculate the distance to the target based on the phase difference between the reference signal and the phase of the reference signal is performed serially, the sum of both processing times becomes the measurement time, and if the amount of data in each processing is not reduced, Measurement time cannot be shortened.

  The present invention has been made in view of the problems of the prior art, and an object thereof is to shorten the measurement time.

  In order to achieve the above object, in the lightwave distance meter according to claim 1, a light emitting means for emitting light modulated by a reference signal, and light introduced from the light emitting means to be sent to the measurement optical path as distance measuring light. Light is introduced from the first light transmitting means that emits light and the light emitting means, the introduced light is distributed to the first reference light or the second reference light, and the first reference light is sent to the first reference light path. , Second light transmitting means for transmitting the second reference light to a second reference optical path, reference optical path blocking means for blocking either the first reference optical path or the second reference optical path, and the first When the reflected light reflected by the measurement optical path is received along with the distance measurement light transmitted by the light transmitting means, the received reflected light is guided to the first light receiving path when the first reference optical path is blocked. When the second reference light path is interrupted, the received reflected light is converted into the second A light receiving means for guiding the light to the light receiving path, and when the reflected light is received from the first light receiving path, photoelectric conversion is performed to generate a first ranging signal, and the first reference light is received from the first reference light path. First photoelectric conversion means for generating a first reference signal by performing photoelectric conversion, and generating a second distance measurement signal by performing photoelectric conversion when reflected light is received from the second light receiving path. Second photoelectric conversion means for generating a second reference signal by performing photoelectric conversion when receiving the second reference light from the two reference light paths, and the first ranging signal and the second reference signal for the reference signal Computing means for computing a phase difference between the second ranging signal and the first reference signal with respect to the reference signal, and computing a distance to the target on the measurement optical path based on one of the computation results And configured.

  (Operation) In the process in which the light modulated by the reference signal is transmitted to the measurement optical path as distance measurement light and is transmitted to the second reference optical path as the first reference optical path or the second reference optical path as the first reference light When the light receiving means receives the reflected light reflected by the measurement light path in response to the transmission of the distance measuring light, and the first reference light path is interrupted, the reflected light is photoelectrically converted to generate a first distance measuring signal. At the same time, the second reference light is photoelectrically converted to generate a second reference signal, and the phase difference between the first ranging signal and the second reference signal with respect to the reference signal is calculated. On the other hand, when the second reference light path is interrupted when the reflected light is received, the reflected light is photoelectrically converted to generate a second ranging signal, and the first reference signal is photoelectrically converted to generate the first reference signal. Then, the phase difference between the second ranging signal and the first reference signal with respect to the reference signal is calculated, and the distance to the target on the measurement optical path is calculated based on the calculation result of one of the phase differences.

  That is, the calculation for obtaining the phase difference between the first distance measurement signal obtained from the distance measurement light transmitted to the measurement optical path and the second reference signal obtained from the second reference optical path is performed simultaneously or obtained from the measurement optical path. Since the processing for calculating the phase difference of the obtained second ranging signal and the phase difference of the first reference signal obtained from the first reference optical path is performed at the same time, the phase difference calculation for the measurement optical path and the phase difference calculation for the reference light are performed. The measurement time can be shortened as compared with the case where the processes are executed separately.

  In the lightwave distance meter according to claim 2, a light emitting means for emitting light modulated by a reference signal, and a first light sending means for introducing light from the light emitting means and transmitting it as a distance measuring light to a measurement optical path. Then, light is introduced from the light emitting means, the introduced light is distributed to the first reference light or the second reference light, the first reference light is sent to the first reference light path, and the second reference light is sent to the first reference light. 2 a second light transmitting means for transmitting to the reference light path, a reference light path blocking means for blocking either the first reference light path or the second reference light path, and a distance measuring light by the first light transmitting means. When the reflected light reflected by the measurement optical path with light transmission is received, when the first reference optical path is blocked, the received reflected light is guided to the first light receiving path, and the second reference optical path is blocked. A light receiving means for guiding the received reflected light to the second light receiving path, When the reflected light is received from the first light receiving path, photoelectric conversion is performed to generate a first ranging signal, and when the first reference light is received from the first reference light path, photoelectric conversion is performed to perform the first conversion. A first photoelectric conversion means for generating a reference signal; and a second ranging signal is generated by performing photoelectric conversion when reflected light is received from the second light receiving path, and the second reference is generated from the second reference optical path. Second photoelectric conversion means for generating a second reference signal by performing photoelectric conversion when receiving light; a phase difference between the reference signal and the first ranging signal; and the reference signal and the second reference signal A phase difference is calculated, a phase difference between the reference signal and the second ranging signal and a phase difference between the reference signal and the first reference signal are calculated, and a target on the measurement optical path is calculated based on the calculation results. And a calculation means for calculating the distance to.

  (Operation) In the process in which the light modulated by the reference signal is transmitted to the measurement optical path as distance measurement light and is transmitted to the second reference optical path as the first reference optical path or the second reference optical path as the first reference light When the light receiving means receives the reflected light reflected by the measurement light path in response to the transmission of the distance measuring light, and the first reference light path is interrupted, the reflected light is photoelectrically converted to generate a first distance measuring signal. At the same time, the second reference light is photoelectrically converted to generate a second reference signal, and the phase difference between the first ranging signal and the second reference signal with respect to the reference signal is calculated. On the other hand, when the second reference light path is interrupted when the reflected light is received, the reflected light is photoelectrically converted to generate a second ranging signal, and the first reference signal is photoelectrically converted to generate the first reference signal. Then, the phase difference between the second ranging signal and the first reference signal with respect to the reference signal is calculated, and the distance to the target on the measurement optical path is calculated based on the calculation result of each phase difference.

  In other words, the calculation for obtaining the phase difference between the first distance measurement signal obtained from the distance measurement light transmitted to the measurement optical path and the second reference signal obtained from the second reference optical path is performed simultaneously and obtained from the measurement optical path. Since the processing for calculating the phase difference of the second ranging signal and the phase difference of the first reference signal obtained from the first reference optical path is performed simultaneously, the phase difference calculation regarding the measurement optical path and the phase difference calculation regarding the reference light are performed. The measurement time can be shortened compared with the case where they are executed separately.

  For example, if the sum of the data amount of the phase difference calculation for the measurement optical path and the data amount of the phase difference calculation for the reference optical path is made constant, the time required for measurement can be reduced to half.

  In the lightwave distance meter according to claim 3, a light emitting means for emitting light modulated by a reference signal, and a first light sending means for introducing light from the light emitting means and sending it to the measuring optical path as distance measuring light Then, light is introduced from the light emitting means, the introduced light is distributed to the first reference light or the second reference light, the first reference light is sent to the first reference light path, and the second reference light is sent to the first reference light. 2nd light transmission means which transmits light to 2 reference light paths, and the reference light path control means which opens the first reference light path and the second reference light path and then blocks the first reference light path or the second reference light path And when the first reference light path and the second reference light path are open when the reflected light reflected by the measurement light path is received along with the distance measurement light transmitted by the first light transmission means. The received reflected light is guided between a first light receiving path and a second light receiving path, and the first reference A light receiving means for guiding the received reflected light to the first light receiving path when the path is blocked, and for guiding the received reflected light to the second light receiving path when the second reference light path is blocked; When the reflected light is received from the light receiving path, photoelectric conversion is performed to generate a first ranging signal, and when the first reference light is received from the first reference light path, photoelectric conversion is performed to generate the first reference signal. When the reflected light is received from the first photoelectric conversion means and the second light receiving path, photoelectric conversion is performed to generate a second ranging signal, and the second reference light is received from the second reference light path. Second photoelectric conversion means for performing photoelectric conversion to generate a second reference signal, and when the first reference optical path and the second reference optical path are open, the first reference signal and the second reference signal The phase difference of the reference signal is calculated as a correction value, and then the reference signal is The phase difference of the first ranging signal relative to the reference signal or the phase difference of the second ranging signal relative to the reference signal is calculated, and the distance to the target on the measurement optical path is calculated based on one of the calculation results. And an arithmetic means for correcting the distance value with the correction value.

  (Operation) In the process in which the light modulated by the reference signal is transmitted to the measurement optical path as distance measurement light and is transmitted to the second reference optical path as the first reference optical path or the second reference optical path as the first reference light Before the actual distance measurement, when the reflected light reflected by the measurement light path is received along with the transmission of the distance measuring light, the reflected light is incident on the first photoelectric conversion means and the second photoelectric conversion means. The first reference optical path and the second reference optical path are opened while the first reference optical path is generated by the first photoelectric conversion means, and the second reference is generated by the second photoelectric conversion means. A signal is generated, and the phase difference between the first reference signal and the second reference signal is calculated as a correction value. Thereafter, during actual distance measurement, light modulated by the reference signal is transmitted to the measurement optical path as distance measurement light, and the first reference optical path or the second reference optical path is blocked. When the light receiving means receives the reflected light reflected by the measurement light path as the distance measurement light is transmitted, the first distance signal is generated by photoelectrically converting the reflected light when the first reference light path is interrupted. The phase difference of the first ranging signal with respect to the reference signal is calculated, and the distance to the target on the measurement optical path is calculated based on the calculation result. On the other hand, when the second reference optical path is interrupted when the reflected light is received, the reflected light is photoelectrically converted to generate a second ranging signal, and the phase difference of the second ranging signal with respect to the reference signal is calculated, Based on the calculation result, the distance to the target on the measurement optical path is calculated. At this time, the phase difference between the first reference signal and the second reference signal has already been obtained as a correction value. Therefore, by correcting the phase difference between the reference signals from the distance value, the light receiving system and the light transmission Errors in the system can be eliminated.

  That is, during actual distance measurement, the distance to the target can be obtained with high accuracy by simply generating the first distance signal or the second distance signal, and the phase difference calculation for the measurement light path and the phase difference calculation for the reference light. The measurement time can be further shortened than when the processes are executed separately.

  As is clear from the above description, according to the lightwave distance meter according to the first aspect, the measurement time can be shortened.

  According to the optical distance meter according to claim 2, the measurement time can be shortened.

  According to the optical distance meter according to claim 3, the measurement time can be further shortened.

  Hereinafter, embodiments of the present invention will be described based on examples. FIG. 1 is a block diagram of an optical distance meter showing an embodiment of the present invention, FIG. 2 is a diagram for explaining a signal generation method in measurement mode 1 and a signal generation method in measurement mode 2, and FIG. These are the figures for demonstrating the production | generation method of the signal in the measurement mode 3. FIG.

  In these figures, a phase difference type lightwave distance meter 12 includes a signal generation circuit 14, a laser diode drive circuit 16, a laser diode 18, a light transmission lens 20, beam splitters (half mirrors) 22, 24, a light transmission lens 26, Shutter 28, objective lens 30, optical path switch 32, photodiodes 34 and 36, preamplifiers 38 and 40, amplifiers 42 and 44, band pass filters 46 and 48, mixers (mixers) 50 and 52, low pass filters 54 and 56, A / D converters 58 and 60, a CPU 62, and a display 64 are provided. A collimating telescope for collimating the target is omitted.

  In response to a command from the CPU 62, the signal generation circuit 14 outputs, for example, signals of 30 MHz, 15 MHz, and 250 kHz to the laser diode driving circuit 16 as a reference signal, and a local signal having a frequency different from that of the reference signal. 50 and 52 are output. The laser diode drive circuit 16 drives the laser diode 18 in response to the reference signal, and modulates the amount of light (laser light) emitted from the laser diode 18 according to the reference signal. That is, the laser diode 18 is configured as a light emitting unit that emits light whose light amount is modulated by the reference signal, and the light emitted from the laser diode 18 passes through the light transmitting lens 20 and enters the beam splitters 22 and 24. It is like that.

  The beam splitter 22 transmits a part of the light emitted by the laser diode 18 as it is, reflects the remaining light, and transmits it as a first reference light 100 to a first reference optical path (not shown). Yes. The light that has passed through the beam splitter 22 enters the beam splitter 24, and a part of the incident light passes through the beam splitter 24 as it is, and passes through the light transmission lens 26 to the measuring optical path (not shown), and the distance measuring light 102. The remaining light is reflected and transmitted as a second reference light 104 to a second reference light path (not shown). The beam splitters 22 and 24 may be parallel plane glass. In this case, about 4% is reflected.

  That is, the light transmitting lens 20, the beam splitters 22 and 24, and the light transmitting lens 26 are configured as first light transmitting means that introduces light accompanying light emission of the laser diode 18 and transmits the light as distance measuring light 102 to the measurement optical path. In addition, the light accompanying the light emission of the laser diode 18 is introduced, the introduced light is distributed to the first reference light 100 or the second reference light 104, and the first reference light 100 is transmitted to the first reference light path. The second reference light 104 is configured as a second light transmitting means for transmitting the second reference light 104 to the second reference light path.

  A shutter 28 is disposed in the vicinity of the optical path of the first reference light path through which the first reference light 100 propagates and the second reference light through which the second reference light 104 propagates. The shutter 28 blocks the first reference light path and blocks the propagation of the first reference light 100 in the measurement mode 1 among the measurement modes 1 to 3, and blocks the second reference light path and blocks the second reference light path in the measurement mode 2. 2 is configured as a reference light path blocking means for blocking the propagation of the reference light 104. Further, in the measurement mode 3, the shutter 28 opens the first reference light path and the second reference light path, passes the first reference light 100 and the second reference light 104 as they are, and then performs the first reference light path during the actual distance measurement. It functions as reference optical path control means for blocking the propagation of the first reference light 100 by blocking the first reference light path, or blocking the propagation of the second reference light 104 by blocking the second reference light path. .

  When the distance measuring light 102 irradiated toward the measurement optical path is reflected by the target on the measurement optical path, the reflected light enters the objective lens 30, and the reflected light incident on the objective lens 30 is reflected on the objective lens 30. Is incident on the optical path switch 32. The optical path switch 32 switches the light receiving path according to the measurement mode mechanically or optically or in conjunction with the shutter 28 based on a command from the CPU 62. For example, in the measurement mode 1, the optical path switch 32 converts the reflected light incident from the objective lens 30 into the first light receiving path (the optical path switch 32 and the photodiode) on the condition that the first reference light 100 is shielded. In the measurement mode 2, on the condition that the second reference light 104 is shielded, the reflected light from the objective lens 30 is reflected on the second light receiving path (the optical path switch 32 and the photo path). The light receiving means is guided to a light receiving path connecting to the diode 36. Further, in the measurement mode 3, the optical path switch 32 transmits the reflected light from the objective lens 30 on the first light receiving path (optical path switch 32) on condition that the first reference optical path and the second reference optical path are open. And a second light receiving path (light receiving path connecting the optical path switch 32 and the photodiode 36), and reflected light from the objective lens 30 is reflected between the photodiode 34 and the photodiode. The light receiving path is switched so that it does not enter 36, and then the reflected light incident from the objective lens 30 is changed to the first light receiving path (optical path switching) on condition that the first reference light 100 is shielded during actual distance measurement. On the other hand, the reflected light from the objective lens 30 is reflected to the second light receiving path on the condition that the second reference light 104 is shielded. Is configured as a light receiving means for switching the light path to direct the light path) that connects the optical path switching device 32 and the photodiode 36.

  The photodiode 34 is configured using a photoelectric conversion element. In the measurement mode 1, when the reflected light is received from the optical path switch 32, the photodiode 34 performs photoelectric conversion to generate a first distance measurement signal. 1, the first reference light 100 is generated from the beam splitter 22 to generate a first reference signal by performing photoelectric conversion. The photodiode 36 is configured by using a photoelectric conversion element. In the measurement mode 1, when the second reference light 104 is received from the beam splitter 24, the photodiode 36 performs photoelectric conversion to generate a second reference signal, and the measurement mode 1 2 is configured as a second photoelectric conversion means that performs photoelectric conversion when receiving reflected light from the optical path switch 32 to generate a second distance measurement signal.

  The first ranging signal or the first reference signal generated by the photodiode 34 is amplified by the preamplifier 38 and then further amplified by the amplifier 42, and the amplified signal is input to the mixer 50 after passing through the band pass filter 46. . The signal input to the mixer 50 is mixed with the local signal from the signal generation circuit 14, converted into an intermediate frequency signal (first distance measurement signal or first reference signal), and then passed through the low-pass filter 54 to obtain the A / It is input to the D converter 58. The first ranging signal or the first reference signal based on the intermediate frequency is converted into a digital signal by the A / D converter 58 and processed by the CPU 62 as digital data.

  On the other hand, the second ranging signal or the second reference signal generated by the photodiode 36 is amplified by the preamplifier 40 and further amplified by the amplifier 44, and the amplified signal is input to the mixer 52 after passing through the band pass filter 48. Is done. The signal input to the mixer 52 is mixed with the local signal from the signal generation circuit 14, converted into an intermediate frequency signal (second ranging signal or second reference signal), and then passed through the low-pass filter 56 to obtain the A / Input to the D converter 60. The second ranging signal or the second reference signal having an intermediate frequency is converted into a digital signal by the A / D converter 60 and processed by the CPU 62 as digital data.

  The CPU 62 captures the digital signal from the A / D converters 58 and 60 while monitoring the generation timing of the reference signal generated from the signal generation circuit 14. In the measurement mode 1, the CPU 62 calculates the phase difference between the reference signal and the first distance measurement signal. The calculation to obtain and the calculation to obtain the phase difference between the reference signal and the second reference signal are performed simultaneously. In measurement mode 2, the calculation to obtain the phase difference between the reference signal and the second ranging signal and the position of the reference signal and the first reference signal. The calculation unit is configured as a calculation unit that simultaneously executes a calculation for obtaining a phase difference, calculates a distance to the target on the measurement optical path based on each calculation result, and displays the calculation result on the display unit 64.

  Next, when the distance to the target is obtained using the lightwave distance meter 12, the light emitted from the laser diode 18 is emitted as the distance measuring light 102 toward the measurement optical path, and as the first reference light 100, the first reference. In the process of being transmitted to the second reference optical path as the optical path or the second reference light 104, the process in the measurement mode 1 and the process in the measurement mode 2 are alternately executed a plurality of times. For example, in the measurement mode 1, the first reference light 100 from the beam splitter 22 is shielded by the switching operation of the shutter 28 and the optical path switch 32, as shown in FIG. 2 The reference light 104 enters the photodiode 36, and the reflected light when the distance measuring light 102 is reflected by the target enters the photodiode 34 from the objective lens 30 and the optical path switch 32. As a result, the CPU 62 performs distance calculation based on the first distance measurement signal generated by the photodiode 34 and the second reference signal generated by the photodiode 36.

  That is, the CPU 62 simultaneously performs a calculation for obtaining the phase difference between the reference signal and the first ranging signal and a calculation for obtaining the phase difference between the reference signal and the second reference signal. In this case, assuming that the wavelength of the modulation signal is λ and the data related to one wavelength is 1, for example, 3000 pieces of data are processed to obtain the phase difference between the reference signal and the first ranging signal and 1500 pieces. Minute data is processed to calculate the phase difference between the reference signal and the second reference signal. Then, the distance to the target on the distance measuring optical path is calculated based on the calculation result of each phase difference. For example, the distance d to the target is calculated according to distance d = phase difference / wavelength of distance measurement signal / 2π. At this time, an error in the light transmission system including the laser diode 18 can be eliminated by obtaining the difference between the two.

  Next, in the measurement mode 2, the second reference light 104 from the beam splitter 24 is shielded by the switching operation of the shutter 28 and the optical path switch 32, as shown in FIG. The first reference light 100 is incident on the photodiode 34, the reflected light when the distance measuring light 102 is reflected by the target is incident on the photodiode 36, the first reference signal is generated by the photodiode 34, and the photodiode 36 A second ranging signal is generated. In the CPU 62, the calculation for obtaining the phase difference between the reference signal and the second ranging signal and the calculation for obtaining the phase difference between the reference signal and the first reference signal are simultaneously executed. In this case, assuming that the wavelength of the modulation signal is λ and the data related to one wavelength is 1, for example, 3000 pieces of data are processed to obtain the phase difference between the reference signal and the second ranging signal and 1500 pieces. Minute data is processed to calculate the phase difference between the reference signal and the first reference signal. An error in the light transmission system including the laser diode 18 can be eliminated by calculating the difference between the two when calculating the distance to the target on the distance measuring optical path based on the calculation result of each phase difference.

  Furthermore, the error in the light receiving system including the photodiode 34 and the photodiode 36 can be eliminated by subtracting the calculation result in the measurement mode 1 and the calculation result in the measurement mode 2.

  As described above, in the present embodiment, in the measurement mode 1, the calculation for obtaining the phase difference between the reference signal and the first ranging signal and the calculation for obtaining the phase difference between the reference signal and the second reference signal are simultaneously performed, and the measurement mode 2 Simultaneously calculate the phase difference between the reference signal and the second ranging signal and calculate the phase difference between the reference signal and the first reference signal, and calculate the distance to the target on the measurement optical path based on each calculation result. Since it did in this way, measurement time can be shortened rather than performing the phase difference calculation regarding a measurement optical path, and the phase difference calculation regarding a reference light separately.

  Further, according to the present embodiment, if the sum of the data amount of the phase difference calculation for the measurement optical path and the data amount of the phase difference calculation for the reference optical path is made constant, the time required for the measurement is reduced by half. be able to.

  When the measurement time is the same as the conventional time, the sum of the data amount in measurement mode 1 and the data amount in measurement mode 2 is doubled, so that the measurement accuracy can be further improved.

  Further, instead of executing the ranging calculation in the measurement mode 1 and the ranging calculation in the measurement mode 2, the distance to the target on the measurement optical path can be obtained based on the ranging calculation in the measurement mode 1 or the measurement mode 2. .

  Next, in the measurement mode 3, as shown in FIG. 3A, the shutter 28 is disposed at a position deviated from the first reference optical path and the second reference optical path by the switching operation of the shutter 28 and the optical path switch 32. The first reference light 100 from the beam splitter 22 enters the photodiode 34, the second reference light 104 from the beam splitter 24 enters the photodiode 36, and a first reference signal is generated by photoelectric conversion of the photodiode 34. Then, the second reference signal is generated by photoelectric conversion of the photodiode 36, and the CPU 62 calculates the phase difference between the phase of the first reference signal and the phase of the second reference signal as a correction value. Thereafter, actual distance measurement is executed.

  When only the first distance measurement signal is generated by actual distance measurement, the transmission of the first reference light 100 is blocked by the shutter 28 as shown in FIG. The reflected light is received by the photodiode 34, a first distance measurement signal is generated by photoelectric conversion of the photodiode 34, and the CPU 62 obtains the phase difference between the phase of the reference signal and the phase of the first distance measurement signal. Find the distance to the target based on At this time, since the phase difference between the phase of the first reference light 100 and the phase of the second reference light 104 has already been obtained as a correction value, the correction is performed by subtracting the phase difference between the reference signals from the distance value. Errors in the system and the light transmission system can be eliminated. For this reason, the distance to the target can be obtained with high accuracy by generating only the first distance measurement signal during actual distance measurement, and the measurement time can be further shortened.

  On the other hand, when only the second ranging signal is generated, the transmission of the second reference light 104 is blocked by the shutter 28 by the switching operation of the shutter 28 and the optical path switch 32, as shown in FIG. Light is received by the photodiode 36, a second distance measurement signal is generated by photoelectric conversion of the photodiode 36, and the CPU 62 obtains a phase difference between the phases of the reference signal and the second distance signal. Also at this time, since the phase difference between the phase of the first reference light 100 and the phase of the second reference light 104 has already been obtained as a correction value, correction by subtracting the phase difference between the reference signals from the distance value is performed. The error in the light receiving system and the light transmitting system can be eliminated. For this reason, the distance to the target can be obtained with high accuracy by generating only the second distance measurement signal during actual distance measurement, and the measurement time can be further shortened.

It is a block block diagram of the light wave distance meter which shows one Example of this invention. (A) is a figure for demonstrating the production | generation method of the signal in the measurement mode 1, (b) is a figure for demonstrating the production | generation method of the signal in the measurement mode 2. FIG. (A), (b), (c) is a figure for demonstrating the production | generation method of the signal in the measurement mode 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Optical wave distance meter 14 Signal generation circuit 16 Laser diode drive circuit 18 Laser diode 22, 24 Beam splitter 26 Light transmission lens 28 Shutter 30 Objective lens 34 Optical path switch 34, 36 Photodiode 50, 52 Mixer 58, 60 A / D conversion 62 CPU

Claims (3)

A light emitting means for emitting light modulated by a reference signal, a first light sending means for introducing light from the light emitting means and sending it to the measuring optical path as ranging light, and introducing light from the light emitting means, The introduced light is distributed to the first reference light or the second reference light, the first reference light is transmitted to the first reference optical path, and the second reference light is transmitted to the second reference optical path. Reflected by the measurement optical path as the distance measuring light is transmitted by the first optical transmission means, the reference optical path blocking means for blocking either the first reference optical path or the second reference optical path, and the first light transmission means When the reflected light is received, the received reflected light is guided to the first light receiving path when the first reference light path is blocked, and the received reflected light is guided to the first light receiving path when the second reference light path is blocked. A light receiving means for guiding the light to the two light receiving paths, and reflected light from the first light receiving path; First photoelectric conversion means for generating a first reference signal by performing photoelectric conversion to generate a first ranging signal and receiving the first reference light from the first reference light path; When the reflected light is received from the second light receiving path, photoelectric conversion is performed to generate a second distance measurement signal, and when the second reference light is received from the second reference light path, photoelectric conversion is performed. A second photoelectric conversion means for generating two reference signals; a phase difference between the first ranging signal and the second reference signal with respect to the reference signal; or the second ranging signal and the first reference signal with respect to the reference signal And a calculation means for calculating a distance to the target on the measurement optical path based on any one of the calculation results. A light emitting means for emitting light modulated by a reference signal, a first light sending means for introducing light from the light emitting means and sending it to the measuring optical path as ranging light, and introducing light from the light emitting means, The introduced light is distributed to the first reference light or the second reference light, the first reference light is transmitted to the first reference optical path, and the second reference light is transmitted to the second reference optical path. Reflected by the measurement optical path as the distance measuring light is transmitted by the first optical transmission means, the reference optical path blocking means for blocking either the first reference optical path or the second reference optical path, and the first light transmission means When the reflected light is received, the received reflected light is guided to the first light receiving path when the first reference light path is blocked, and the received reflected light is guided to the first light receiving path when the second reference light path is blocked. A light receiving means for guiding the light to the two light receiving paths, and reflected light from the first light receiving path; First photoelectric conversion means for generating a first reference signal by performing photoelectric conversion to generate a first ranging signal and receiving the first reference light from the first reference light path; When the reflected light is received from the second light receiving path, photoelectric conversion is performed to generate a second distance measurement signal, and when the second reference light is received from the second reference light path, photoelectric conversion is performed. A second photoelectric conversion means for generating two reference signals; a phase difference between the reference signal and the first ranging signal; and a phase difference between the reference signal and the second reference signal; Calculating means for calculating a phase difference of a second ranging signal and a phase difference between the reference signal and the first reference signal, and calculating a distance to the target on the measurement optical path based on the calculation results; Lightwave distance meter. A light emitting means for emitting light modulated by a reference signal, a first light sending means for introducing light from the light emitting means and sending it to the measuring optical path as ranging light, and introducing light from the light emitting means, The introduced light is distributed to the first reference light or the second reference light, the first reference light is transmitted to the first reference optical path, and the second reference light is transmitted to the second reference optical path. Measurement by means of optical means, reference optical path control means for opening the first reference optical path and the second reference optical path, and then blocking the first reference optical path or the second reference optical path, and the first light transmission means. When the reflected light reflected by the measurement light path is received as the distance light is transmitted, and the first reference light path and the second reference light path are open, the received reflected light is used as the first light receiving path. When the first reference light path is blocked, the light reception is conducted between the second light receiving path and the second light receiving path. When the reflected light is received from the first light receiving path and the light receiving means for guiding the reflected light received to the first light receiving path and guiding the received reflected light to the second light receiving path when the second reference light path is blocked First photoelectric conversion means for generating a first reference signal by performing photoelectric conversion to generate a first ranging signal and receiving the first reference light from the first reference light path; When the reflected light is received from the second light receiving path, photoelectric conversion is performed to generate a second distance measurement signal, and when the second reference light is received from the second reference light path, photoelectric conversion is performed. A second photoelectric conversion means for generating two reference signals; and a phase difference between the first reference signal and the second reference signal when the first reference optical path and the second reference optical path are open as a correction value And then the phase difference of the first ranging signal with respect to the reference signal. Calculates the phase difference of the second ranging signal with respect to the reference signal, calculates the distance to the target on the measurement optical path based on one of the calculation results, and corrects the distance value with the correction value And a light wave distance meter comprising:

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