SU1531690A1 - Method and meter for measuring radiation wavelength - Google Patents

Abstract

The invention can be used in metrology to create p. Spectral imaging devices and measuring laser complexes. The purpose of the invention is to improve the measurement accuracy of the radiation wavelength. The method consists in changing the angles of incidence of the beams. wavelengths with known and sought wavelengths to achieve the same diffraction angle. In this case, the claim by wavelength is determined by the measurement of the angles of incidence and the known values of the calibration wavelengths and the spatial frequency of the periodic structure. The radiation wavelength meter contains an acousto-optic deflector installed in front of the diffraction grating, and a photoelectric recorder, made in the position-sensitive receiver, connected via an operational amplifier with a frequency synthesizer frequency control unit that controls the deflector. 2 sp.f-ly, 1 ill. (L with

Description

/

The invention relates to spectrometry and can be used to create spectral instruments and measuring laser complexes based on the use of pre-tuned lasers.

The aim of the invention is to improve the accuracy of measuring the wavelength of the radiation.

In diffraction of a collimated radiation beam on a periodic structure, in general, the dependence of the wavelength of the radiation I on the lattice period d and the angles of incidence Φ and diffraction is realized.

-I d (sinV + sin) (-1) With a constant diffraction angle Cf const) for different wavelengths, equation (1) is performed at - different angles of incidence. This raises the problem of precision control of the angle of incidence on the periodic structure and the measurement of changes in this angle. For this purpose, for example, the diffraction of a light beam on a controlled sound grating formed by an ultrasonic wave in the light-acoustic wire of an acousto-optic deflector can be used. In this case, the ratio is

SP

with

about

with

. . - | - (sin + sin 9.)

I L

(2)

for any value of the length of the light wave I, -, the diffraction Q and the frequency of the ultrasonic wave (v is the speed of the sound wave in the light-sound material, is the angle of incidence of the light beam on the sound array). By changing the constant value of 1, the deflection angle b, - can be precisely controlled. If the acousto-optic detector is glittered before the periodic structure (r, hfakt (ion regeneration), then the change is 0, equivalent to teitno change (G10 of the angle of incidence of the light beam and the periodic structure, i.e. L0, -. At diffraction beam of irradiation with known polygon lengths, calibration process) on a periodic structure of sprangle

 L; d (sin% f r, in j 1, - u (z (n -t-

(3) (A)

71l radiation beam with an Unknown length (i) y, diffracted under the same angle, performed (em; equation

 rt (sl

SI l j (+ sin f

(five)

Combined erneHiie urannent (3-5) with the equation Vn - 0, - g 4 V, (6), H, 0, (7) allows to determine the desired wavelength. according to the known values of d ,, and, measured t-1, m

Measurement accuracy, (determined by the accuracy of determining the wavelengths, and, by fixing the constant value of the diffraction angle; the accuracy of the space-angle joint, and the outgoing beam With a wavelength of 4 2 down to pair-wise with -1 p s K ur V , accurate measurement of the angle of incidence.

, At 4epT yKf i nnedena, the optical circuit is a measuring instrument for the wavelength of radiation, which implements this method.

The device contains sequentially raspppo: 41gp, 1. optical system forviropacmr in: jrio4 divider - Hbrfi cube 1, .igix-electronic estimate of the combination of software for calibration gauges and. ritual beams,

The state consists of a lens 2, in the focal plane 3 of which there is a no-action-sensitive photodetector 4 connected to an operational amplifier 5 and a recording device 6, a radiation expander 7, followed by an acousto-optical deflector 8, sequentially

diffraction grid 9 and photoelectric recorder placed behind the focusing lens) 0 in its focal plane 11. Recorder -. Consists of a position-sensitive5 receiver 12, electrically connected to an operational amplifier 13 and a recording device 14. The device further comprises a radio frequency synthesizer 15 with a block 16

Q is a smooth frequency control and a radiation wavelength control unit 17. The synthesizer 15 is electrically connected to the acousto-optic deflector 8, and the block 16 of the smooth frequency control

5 is connected to the operational amplifier 13. As the receiver 12, a line of position-sensitive receivers can be used.

The device works as follows.

At the stage of calibration, radiation beams with known wavelengths and 1 are aligned along the direction of a. Using the power of the system of elements 2-6, the Yug4y function of the spatial-angular filter, obtaining the same signal from the photodetector 4 on the registering device 6. Then the beams extended by the telescope are sequentially directed to the diffraction grating 9 fixed by a photoelectric recorder (12-14). The frequencies of the diode signals controlling the deflector B, in which the signal from receiver 12 to register device 14 has the same value, are monitored. Parallel information about this comes from the operational amplifier 13 to the Zlok 16 of the smooth frequency control, stopping the tuning of the frequency synthesizer 15. As a result, a constant diffraction angle and a control of the angle of incidence on the diffraction grating are obtained for radiations with wavelengths and K. Then, a beam of beam with measurements

five

0

0

five

1P

wavelength. Combine it in the direction of the beams 7, using the system of elements 2 - 6, and then select and fix the value of the frequency of the radio signal at which the beam

 falls exactly on the position-pinch receiver 12. The difference in the frequency values is unambiguously related to the change in the deflection angle, i.e. with a change in the angle of incidence of each beam onto the lattice, which makes it possible to solve a system of equations of type (3-7). As a result, the emission wavelength control unit 17 detects and outputs the value of L.

I

Claims (2)

1. A method of measuring the radiation wavelength, which consists in sending a collimated radiation beam to the periodic structure from a single wave and recording the angular displacements of the diffracted focused beam, characterized in that, in order to improve the measurement accuracy, the periodic structure sequentially directed along the direction of the radiation beams with known lengths of will I, and the measured wavelength The / i fixes the location of the diffracted focused beam with the wavelength I,, and changes the angles of incidence of the radiation beams with wavelengths  L to coincide the location of the diffracted focused beams of these wavelengths with a previously recorded for a beam with a wavelength JY and determine the desired wavelength I If based on the measured changes dc of the angles of incidence, the known values of the wavelengths C, il and the spatial frequency d of a periodic structure from the system of equations: -I, -d (sin 4-pgpc) 1j-d (sin i + sin) (l (sin)  LC, ii (one) (2) -, one where V,, V, Ф are the angles of incidence of light beams with wavelengths Л,, 71 jf /, respectively, on the periodic structure -, tour, Cf are the diffraction angles of the light i-i beams. 2. A radiation wavelength meter containing an optically coupled beam forming system, a spatial angular filter, a diffraction grating, a focusing lens, and a photoelectric recorder located in the focal plane of the objective, characterized in that An acousto-optic deflector, a frequency synthesizer, blocks for smooth frequency adjustment and radiation wavelength control are added to the device, with the deflector placed in front of the diffraction grating and set It is designed so that the deflection plane of the beam coincides with the grating dispersion plane, the photoelectric recorder is made in the form of a position-sensitive photodetector electrically connected with series-connected operational amplifier and the indicator of the position of the focused diffracted beam, the frequency synthesizer is connected to the output of the smoothness control unit and a unit for controlling the wavelength of the radiation, and the input of the frequency modulating unit is connected to the output of the operational amplifier. L, A,