SU1760315A1 - Pulse distance meter - Google Patents

Abstract

Use: measuring equipment, in geodesy, navigation, location, geophysical research. SUMMARY OF THE INVENTION: The range finder includes a laser emitter 1, a control unit 2, 1 a transceiver optical unit 3, a reference pulse sensor 4, a spectral selector 5, two photoreceivers 6 and 9, two time interval meters 7 and 13, a computing unit 8, a coupling capacitor 10, the inverter 11 and the diode 12. 2-1- 3-5-9-10-11-13-8. 5-6-7-8. 1-4-5. 2 Il.

Description

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The invention relates to the field of high-precision measurements using laser radiation and can be used in geodesy, navigation, location, and geophysical surveys.

A device for measuring the distance is known, based on measuring the transit time of a radiation pulse from an object and back.

The main disadvantage of the known range finder is its low noise immunity and, consequently, low measurement accuracy. This disadvantage is due to the fact that random interference, for example, caused by multiple reflections, scattering, non-stationary absorption of a radiated signal, inhomogeneous media, etc., is not eliminated.

The closest to the claimed rangefinder in terms of technical essence is a pulse rangefinder containing a laser emitter with a control unit, optically coupled to the first photoreceiver via the optical node of the reference pulse, as well as a computing unit connected to the first and the second time interval meter, the first of which is connected to the first photodetector.

The main disadvantage of the known range finder is the large measurement time, i.e. poor performance due to the use of accumulation.

The purpose of the invention is to increase performance while maintaining high noise immunity.

The goal is achieved by the fact that a pulse rangefinder containing a camp emitter with a control unit is optically coupled to the first photodetector via the optical reference pulse unit, as well as through the transceiver optical unit, a computing unit connected to the first and second time interval meters the first of which is connected to the first photodetector, a spectral selector and a second receiver connected in series, a splitter capacitor and an inverter are inputted, the output of which is connected The second emitter is configured to emit at two wavelengths, the second photodetector is optically wired with the laser emitter through the optical node of the reference pulse and through the transceiver optical unit, and the spectral selector is placed in front of the first and second photodetectors.

This inverter input is connected to the cathode of the input diode, the anode of which is connected to the zero bus.

A semiconductor laser is used as the radiation source in the device. The control unit sets a constant current through the laser diode, the value of which slightly exceeds the threshold value at which laser radiation starts to be generated at a wavelength of g. Current pulses with a duration of 50 n are applied to a constant bias, as a result of which the laser begins to generate AI at a different wavelength. . Moreover, due to current tuning under the action of short current pulses (nanosecond duration), the spectrum shifts to the shortwave region, i.e. h. Ai. (On figa 2 shows the laser radiation at a wavelength of AL in Fig.26 - radiation. At a wavelength, Aa). The difference AZ - AI can reach 50-100 A.

The essence of the invention lies in the fact that due to the use of the operating mode of a pulsed radiator with a constant offset and the introduction of several simplest elements into the rangefinder circuit, an additional measuring channel is formed which acts parallel to the main channel and simultaneously with it. This allows you to accumulate the required number of measurement results, which is necessary to achieve a given noise immunity twice as fast as when using a single measurement channel.

The proposed device differs from the prototype in that a spectral selector, a second radiation receiver, a coupling capacitor, a diode, an inverter, and the corresponding functional connections of the inserted units with the elements of the prototype device are implemented.

Figure 1 presents the structural diagram of the proposed rangefinder; 2 shows timing diagrams for the operation of the range finder. (On figa - the signal emitted at the wavelength AI; on fig.26 - the signal emitted at the wavelength A2; on figv - the signal at the output of the first meter of time intervals; on fig.2g - the signal at the output of the second photodetector ; Figure 2d is the signal at the output of the inverter; Figure 2e is the signal at the input of the second time interval meter).

The range finder works as follows.

The emitter 1 under the action of the control unit 2 emits a signal at two lengths

waves alternately through the transmitting optical unit 3 in the direction of the object. At the same moments, reference signals are generated in the sensor 4 of the reference impulse, which arrive at the spectral selector 5. The impulse signal from the distance goes through the receiving optical unit 3 also to the selector 5. The spectral selector 5 spatially separates em reflects the reflected and reference signals of the radiation signal at the wavelength AI, falling on the photodetector 6, and the radiation signal at the wavelength AA, falling on the photodetector 9. After registration of the optical pulses on d ine AI wave electric signal by a photodetector 6 of Fig, 2c is supplied to the meter 7 timeslots. The signal at the wavelength Xg, registered by the photoreceiver 9, through the coupling capacitor 10, the inverter 11 is fed to the meter 13 time intervals (figure 1). The input of the photodetector 9 receives two optical signals (reference and clipped) of constant amplitude with short pauses, the shape of which corresponds to the shape of the signal emitted at the wavelength (Fig. 26). Therefore, at the input of the photodetector a signal acts, the form of which is shown in FIG. .

The diode 12 serves to tie the signal passing through the coupling capacitor 10 to the zero level (Figure 2d). Inverter 11 converts negative-shaped pulses (inverted) (figd) into positive pulses (fig.2e), similar to those arriving at the input of the first meter 7 time intervals (fig. 2b). At the same time as the inverter 11 can be used a digital element (NOT) of the same series, on which the meters 7 and 13 time intervals are built.

Computing device 8 performs static processing of measurement results by accumulating them. Since optical signals with different wavelengths are used in the primary and secondary channels, therefore, the measurement results in the primary and secondary channels are statistically independent, thereby reducing the accumulation time of the statistical sample of the required volume. At the same time, the amount of statistical sampling, which ensures a given accuracy of distance measurement in the conditions of interference, is determined by the intensity of random noise.

Thus, by using the mode of operation of a pulsed radiator with a constant bias and the introduction of a spectral selector, a second receiver, a coupling capacitor, a diode and an inverter into the device, an additional statistically independent measuring channel is formed, which acts parallel to the main and. simultaneously with it, which allows you to accumulate the required

the number of measurement results that is needed to achieve a given noise immunity is twice as fast as when using a single measurement channel. In this case, the proposed device

Both channels use the same complex and expensive transceiver unit, which makes it possible to shorten the measurement time by half without significantly increasing hardware costs.

Claims (1)

Invention Formula A pulse rangefinder containing a laser emitter with a control unit, optically coupled to the first photodetector via the optical reference node pulse, as well as through a transceiver optical unit, a computing unit connected to the first and second time interval gauges, the first of which is connected to the first photodetector, characterized in that it is equipped with a spectral selector and connected in series by the second photodetector, in order to increase performance, a coupling capacitor and an inverter, the output of which is connected to the second time interval meter, the laser emitter is configured to emit at two wavelengths, Ora photodetector optically coupled to the laser emitter via the optical node and the reference pulse through the optical transceiver unit, a spectrum selector is placed before the first and photodetectors Etoro people, with This inverter input is connected to the cathode of the input diode, the anode of which is connected to the zero bus. P Schig.2