SU1323866A1 - Method and device for registering spectral lens - Google Patents

Abstract

The invention relates to spectroscopy. The aim of the invention is to simplify the method of registering the spectrum and simplify the device that implements it, expanding the spectrum under study. The invention makes it possible to record different, on the basis of the spectral amplitude, the satellites by siphronno accumulation of signals of multiple sweep in the frequency range or wavelength under study, tied to the characteristics used within the range of rendered spectral imaging. This is achieved by determining the extremum of the selected line during each single scan and summation with accumulation of the amplitudes of the spectrum during repeated scanning so that the extreme values of the selected rener line of each single scan are identical. 2 sec. n f-ly, 1 ill. € (L oo oo 00 05 O5

Description

The invention relates to spectroscopy of various ranges. H can be used for spectral analysis of substances and compounds in the technological and environmental monitoring of media purity.

The aim of the invention is to simplify the method of recording the spectrum and the device, as well as expanding the spectral range under study and improving the measurement accuracy.

The drawing shows a device with the help of which it is possible to register spectral lines.

The device consists of a spectrum acquisition unit 1, which includes a tunable laser 2 with a tuning element 3, a piezoelectric ceramic, an absorbing cell 4 with the test substance, a detector 5, an analog-digital converter 6, a frequency lock unit 7, and consists of a shift register 8 , amplitude discriminator 9 and memory cell register 10, spectral recording unit 11, consisting of accumulating adder 12, digital-analogue converter 13 and recorder 14, scanning device 15, consisting of 16 clock pulse generator, counter 17 and digital-analog converter 18.

The method is carried out as follows.

A scanning device using a generator of 16 clock pulses, the counter 17, forms a sawtooth sweep voltage at the output of the D / A converter 18, which, through the piezo-ceramics 3, controls the tuning of the laser 2 in the selected frequency range. The absorption spectrum of the cell 4 under study is extracted as a voltage in the photodetector 5 and is converted to digital form in the A / D converter 6. Each pulse (clock) of the generator 16 controls the encoding of a single number in the A1LC, its write to the shift register 8 and the comparison in the combinational adder 9 of this current and previous values of the spectral amplitude from the ADC 6. If the current value is more than the previous one, the signal from the adder 9 gates write to cell-register 10 number (address) of reference with the maximum amplitude of the spectrum at the current clock cycle. As a result of a single sweep, register 10 records the address of the extreme (in this case, maximum) value of the single-scan spectrum. At the end of the sweep in adder 9, the difference (shift) between the extremum address and its required position is determined by the slash, specified by the number of AEs in the form of a constant from the console. The choice of AE value depends on the task and can be determined, for example, at the beginning of the scan range or in its middle. The magnitude and direction of the shift from the output of the adder 9 controls through the shift register 8 the sum

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By compiling the amplitudes of the spectrum of each scan in the accumulating adder 12. Measurement results after each scan or accumulation can be output through the DAC 13 to a two-coordinate recorder 14 controlled by the sweep from the output of the DAC 18.

The main parameters of the implemented spectrometer: laser radiation wavelength 3.39 µm, the maximum number of frequency channels 1024, the frequency tuning range of the laser is O-100 MHz, the scan rate of the range 0.5 s.

The invention significantly simplifies the spectrometer circuit by eliminating the external, additional reference frame, forming it within the scanned range using the extremes of the most intense line or other features of the lines of the scanned range, which opens up the possibility of expanding the spectral range being studied regardless of the presence of a suitable additional reference line. . In addition, the exclusion of the measuring path with the difference frequency of tunable and stable lasers also broadens the range in the specifically implemented scheme as compared to the known ones.

Claims (2)

1. A method of recording spectral lines based on multiple scanning in the studied frequency range or wavelengths, snapping the studied range of the spectrum to a frequency reference, measuring the amplitudes of the spectrum during each scanning and accumulating them by summing, in order to simplify the method registering the spectrum and expanding the spectral range under study, choose each scan within the range of one of the lines of the spectrum as a reference, determine its extremum and summarize the values from Eren the spectrum amplitude at multiple scanning so that the extreme values of the selected reference scan line of each single match. 2. A device for recording spectral lines, comprising a spectrum acquisition unit, consisting of successively tunable laser with a tuning / absorbing cell element, a detector, the output of which is connected to an analog-to-digital converter, a scanning unit made in series connected clock generator, counter, digital-to-analog converter, the output of which is connected to the tunable laser tuning element, frequency-frequency block, the output of which is connected with an input of a spectrum recording unit, characterized in that, in order to simplify the construction, expand the spectral range under study and improve measurement accuracy, the frequency lock unit has an extremum determination circuit that contains an amplitude discriminator, a memory cell, and a shift register, one from the amplitude discriminator inputs and the register input the shift is connected to the output of the spectrum acquisition unit, the other input is connected to the memory cell output, and the memory cell inputs are connected to the amplitude discriminator output and the counter output, the shift register output is connected to the first recorder input, and the amplitude discriminator output.