SU1420387A1 - Quick-operating spectrometer - Google Patents

Abstract

The invention relates to optical fabrication and can be used to determine the color of an area. The purpose of the invention is to ensure the accuracy of the measurements. Radiation of a certain spectral composition formed by a mo o (x) () matic illuminator 1, iipoeiuil ve Tc per object. At the end of the scan of the illuminator 1, the scanning of the emission spectrum of the illuminator 2 begins. With different directions of dispersion of the illuminators 1 and 2, a signal is formed on the photoelectric transducer that characterizes the reflection or transmission of the object under study. This signal consists of two maxima arriving at the electronic; 1 maximum 8 detector. The signal converted to two short sharp pulses arrives at trigger 9 and then at element 10. At the other input of element 10, pulses are received from generator II. The number of pulses is counted by the counter 12 and is indicated by the block 13. The use of this electronic detector of the maximum allows to eliminate the error associated with the inaccuracy of determining the maximum current at the output of the photovoltaic converter. 2 Il. C (L

Description

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The invention relates to optical instrumentation and can be used to determine the color of an object, such as a liquid crystal in cholesteric mesophase.

The aim of the invention is to improve the measurement accuracy.

FIG. 1 shows a flow chart of a high-speed spectrometer; in fig. 2 - the electronic maximum detector circuit is functional.

The speed spectrophotometer contains the first monochromatic illuminator 1, the second monochromatic illuminator 2, the first output slit 3 and the second output P1el 4, the focusing lens 5, the sample holder 6 for the sample with the object of study, the photoelectric converter 7, the electronic maximum detector 8, trigger 9 with a counting input, the logical element And 10, the generator 11 exemplary frequency counter 12 pulses and block 13 of the display.

The electronic maximum detector 8 (FIG. 2) consists of differentiating operational amplifiers 14 and 15, a zero detector 16, a threshold detector 17, a logical element And 18 of the forming element 19.

The first and second monochromatic illuminators I and 2 include a light source, condenser lenses, dispersing elements (prisms), rotating mirrors located on a common axis of rotation, and focusing lenses.

Speed spectrophotometer works as follows.

The image of each of the spectra formed by illuminators 1 and 2 is focused in the plane of the corresponding nhelii 3 and 4, which cut out narrow regions of the spectrum corresponding to wavelengths in the interval L. The slits are located in the focal plane of the objective 5, which projects the image of both spectra onto the object of study, fixed in the holder 6.

In static with fixed mirrors of illuminators 1 and 2, the image of the spectrum hits only one of the slits (in Fig. 1, for definiteness, an image hit for illuminator 1 is taken) and the object in holder 6 is illuminated with monochromatic light with wavelengths from the interval L.

When the mirrors of the illuminators 1 and 2 are rotated, the spectrum image moves along the plane of the slit 3, 4 and it is illuminated sequentially in time by the long-wave (red) and then short-wave (purple) parts of the spectrum. The object of study is respectively illuminated in the same sequence with light changing color from red to violet. When the spectrum is scanned over slit 3 of the illuminator 1, scanning begins.

the spectrum formed by the illuminator 2 on the slit 4. This is achieved by a certain angular displacement of the plane of the mirror of the illuminator 2 with respect to the plane

mirrors of the illuminator 1, located on the same axis of the rotating engine. In contrast to the above, the order of following the wavelengths of the spectrum from illuminator I through slit 3, the spectrum from illuminator 2 through slit 4 moves in reverse order, i.e., starting from the shortwave (violet) and ending with the longwave (red) parts of the spectrum. This is achieved by a special mirror-symmetric arrangement of the dispersing elements (prisms) of the illuminators 1 and 2, i.e. the directions of dispersion are opposite.

Therefore, after illuminating the object of study with a spectrum formed by illuminator 1 through slit 3 in order of decreasing wavelengths from red to violet, the object of study is illuminated with a spectrum formed by illuminator 2 through slit 4 in order of increasing wavelengths from violet to red. In this case, the intensity of the reflected (transmitted) object has two maxima, the first of which is formed when scanning the spectrum through slit 3 from red to purple, and the second - when scanning the spectrum

through slit 4 from purple to red. These two maxima, which fix the coincidence of the spectral component of the L. of the light flux falling on the object of study, with the color of the object, uniquely determine the color (complementary color)

the sample under study.

The radiation reflected (transmitted) by the object of study enters the photoelectric converter 7, at the output of which an electrical signal is generated,

having successive current maxima, the moments of occurrence of which correspond to the moments of coincidence of the spectral component of the QS, the light flux falling on the object of study with the color of the object. This electrical signal

enters the input of the electronic detector 8 of the maximum, which for each of the current maxima arriving at its input, forms a short sharp pulse, the leading front of which corresponds in time to the appearance of one of the maxima of the input electrical signal. With a single scan of the composite spectrum, the output signal of the electronic detector 8 of the maximum has the form of two short sharp pulses that arrive at the counting input of the trigger 9. The first of

of these pulses, flip-flop 9 flips to one state, and the second returns flip-flop 9 to zero (initial) state. With a single state of trigger 9 signal

from its output it enters the second input of logic element 10 and permits the arrival of pulses from a generator 11 of exemplary frequency to the counting input of counter 12. The process of accumulating pulses from generator 11 through element 10 in counter 12 continues until the moment of the second short a pulse to the counting input of the trigger 9. The trigger 9 returns to the zero state and closes the element 10, which ceases to pass pulses from the generator 11. In this case, the number 12 is recorded in the counter 12, corresponding to etstvuyuschee twice the length of the wave spectrum, for which the maxima formed on the output electrical signal transducer foto.elektronnogo 7.

This number is induced by the display unit 13.

In the device, by using two monochromatic illuminators and measuring the time interval between two moments of the maximum intensity of the reflected (transmitted) by the object of study by means of an electronic detector, the resolution is approximately twice as high as the prototype, since the change in the color of the sample leads to a symmetrical shift in time of both pulses at the output of the detector 8, which limit the measured time interval.

In addition, in the device, both moments limiting the time interval that determines the color (additional color) of the object of study due to the use of a mirror-symmetric composite spectrum are formed by the determined parameter of the optical signal under study - the wavelength of the maximum reflected (transmitted) radiation. This eliminates measurement errors due to the limited sensitivity of the photoconverter, since various changes in the sensitivity of the latter cannot lead to a shift in the current maximum relative to the sound current, as measured by

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The cops arrive at two current maxima. The use of an electronic maximum detector makes it possible to eliminate the error associated with the inaccuracy of determining the maximum current at the output of the photovoltaic converter, since the proposed device records the leading edge of a short sharp pulse.

Due to the introduction of an electronic maximum detector that converts an electrical signal, it is possible to use the device (if necessary) in automated measuring systems.

Claims (1)

Invention Formula A speed spectrophotometer containing an optically coupled first monochromatic illuminator equipped with a spectral scanning unit, a focusing lens, a sample holder and a photoelectric converter, as well as a recording system connected to the photoelectric converter, in order to improve the measurement accuracy, the spectrophotometer additionally contains second monochromatic illuminator equipped with a scanning unit along the spectrum, direction of dispersion of the second monochromatic illuminator The cell is opposite to the direction of dispersion of the first monochromatic illuminator, the scanning units along the spectrum of the first and second monochromatic illuminators are kinematically matched, the recording system contains an electronic maximum detector, a trigger, a logic element And, a sample frequency generator, a pulse counter and a display unit, with a photoelectric converter connected to the input electronic maximum detector, the output of which is connected to the trigger input, the trigger output is connected to the first logic input AND gate, the second input of the AND gate connected to the output reference frequency generator, and the output of NAND gate is connected to the counter input, whose output is connected to the display unit. -Spit FIG. 2