SU1283529A1 - Light range finder - Google Patents

Abstract

The invention relates to a geodetic instrument making and allows to increase the accuracy of distance measurement by a phase-spacing laser, which contains a laser 1, an electro-optical modulator of radiation 2, beam splitting plates 3 and 8, a phase quarter-wave plate 4, optical analyzers 5 and 9, transmitting optical system 7 , photodetector 10, generator 11 of polarizing pulses, generator 12 of scale frequency, local oscillator 13, mixer 14 and digital phase meter 15. Introduction of new elements and formation of new connections between elements The device allows the application of polarizing voltage pulses to carry out electro-optical switching of the measuring and calibration channels. The latter consists of a beam-splitting plate 3, which part of the radiation after the electro-optical modulator 2 of the radiation is directed to the optical analyzer 9, and then to the photodetector 10. 3 sludge. with S (L

Description

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The invention relates to geodetic instrumentation and can be used for highly accurate measurement of distances in geodesy, in the construction of large engineering structures, etc.

The aim of the invention is to increase the accuracy of distance measurement with a phase-luminer.

Fig. 1 shows a schematic diagram of the light range meter, Fig. 2, a static characteristic of an electro-optical modulator; Fig. 3 shows a radiation characteristic in the measuring and calibration channels.

The laser rangefinder contains a laser 1, an electro-optic radiation modulator 2, a first beam-splitting plate 3, a phase quarter-wave plate 4, a first optical analyzer 5, a transmitting optical system 6, a receiving optical system 7, a second beam-splitting plate 8, a second optical analyzer 9, a photodetector 10, a generator polarizing pulses 11, the generator 12 scale frequency, the local oscillator 13, the mixer 14, the digital phase meter 15, the object 16.

The range finder works as follows.

The generator 12 of the large-scale frequency produces a high-frequency voltage, which is supplied to an electrical voltage (O-time tg) (FIG. 3).

directing the local oscillator 13. The reference voltage is created in the mixer 14. The phase difference between the reference voltage in the mixer 14 and the signal at the output of the photodetector 10 is measured by a digital phase meter 15 and is proportional to the measured distance.

To improve the accuracy of measurement of the phase difference and, therefore, increase by taking into account the change in signals due to the instability of the frequency and phase of the generator and local oscillator, possible instability of the modulator, photodetector and other nodes

 There is a span calibration channel, called an optical short circuit. This channel consists of a first beam-splitting plate 3, which, after a modulator, sends part of the radiation to the second optical analyzer 9, and then using the second beam-splitting plate 8, to the photodetector 10.

In the absence of a constant voltage on the modulator, the spectrum of the modulated signal contains only even harmonics.

If there is a constant voltage, the spectrum of the modulated signal contains only the fundamental first and other odd harmonics.

In the absence of a pulse, polarize25

The radiation modulator 2 is made, for example, in the form of a cavity resonator with an electro-optical crystal in a capacitive gap. The laser radiation 1, the passage through the radiation modulator 2 is modulated by polarization. After passing the beam-splitting plate 3 and the phase quarter-wave plate 4, which serves to output the operating point of the modulator to the linear part, and the first optical analyzer 5, the radiation becomes intensity-modulated by means of the transmitting optical system 6, the radiation is collimated and transmitted to the object 16, to which the are distance.

The radiation reflected from the object is received by the receiving optical system 7, passes the beam-splitting plate 8 and is directed to the photodetector 10, operating in frequency conversion mode with the help of additional modulation of the photocurrent voltage (time O – tg) (Fig. 3)

pinning the local oscillator 13. The reference voltage created in the mixer 14. The phase difference between the reference voltage in the mixer 14 and the signal at the output of the photodetector 10 is measured by a digital phase meter 15 and is proportional to the measured distance.

To increase the accuracy of measuring the phase difference and, consequently, the distance due to the change in signals due to the instability of the frequency and phase of the generator and the local oscillator, possible instability of the modulator, photodetector and other nodes

There is a span calibration channel, called an optical short circuit. This channel consists of the first beam-splitting plate 3, which directs part of the radiation after the modulator to the second optical analyzer 9, and then with the help of the second beam-splitting plate 8 - to the photodetector 10.

In the absence of a constant voltage on the modulator, the spectrum of the modulated signal contains only even harmonics.

If there is a constant voltage, the spectrum of the modulated signal contains only the fundamental first and other odd harmonics.

In the absence of a pulse, I polarize

voltage (time O - tg) (fig.Z)

the operating point of the modulator in the measuring channel due to the phase quarter-wave plate is in the linear part of the characteristic and on

The distance is received modulated with the frequency of the generator of the large-scale frequency radiation. I. At the same time, the operating point of the modulator for the calibration channel is at the minimum

characteristics and after the optical analyzer 9 is radiation II, modulated by twice the frequency generator of the scale frequency, therefore, fall on the photodetectors, it

does not cause the occurrence of a signal voltage at its output. When a pulse is applied, the polarizing voltage

T (time-T) to the measuring channel

Radiation II enters the gauge — Radiation III. In this case, the signal voltage at the output of the photodetector is generated by fig. 2

Claims (1)

Invention Formula A light range finder containing a laser and a radiation modulator, a transmitting and receiving optical systems and a photodetector, and a scale frequency generator, a local oscillator, a mixer, and a digital phase meter, the first output of the mas generator 3529 .4 staff frequency is connected to the first input of the modulator, the second output is connected to the first input of the mixer, the second input of which is connected to the first output 5 of the local oscillator, and the output to the first input of the phase meter, the output of the photodetector is connected to the second input of the phase meter, the auxiliary input is connected to the second output a local oscillator, 10 characterized in that, in order to improve the accuracy of the measurement 0 five It is equipped with a generator of polarizing pulses, two beam splitters, two optical analyzers and a quarter-wave phase plate, the first output of the generator of polarizing pulses connected to the third input of the phase meter, and the second output to the second input of the modulator, the first beam splitter, a quarter-wave plate and the first analyzer is sequentially installed between the modulator and the transmitter system, and the second analyzer and the beam splitter are sequentially installed between the first beam splitter and the photodetector and form a calibration channel. FIG. 2 Editor N. Slobod Nick FS / g Compiled by M. Vasiliev Tehred M. Hodannch Proofreader S. Cherni Order 7426/36 Circulation 677 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushska nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4