SU1497605A1 - Method of determining wavelength in the energy concentration maximum of diffraction grate - Google Patents

Abstract

The invention relates to the field of optical spectral instrumentation. The aim of the invention is to improve the accuracy. A monochromatic beam with a wavelength λ illuminates the diffraction grating through the photometric wedge. Equalize the intensities of the beams: reflected from the photometric wedge and the beam of the studied spectral order by changing the transmittance of the wedge. The coefficient ρ _{K + 1, K of the} transmission of the wedge corresponding to the equality of the beams for two consecutive spectral orders is determined. According to the graph of the relation √ _{R + 1} / √ _R = [SIN [N (K-λ ₀ / λ)] (K + 1-λ ₀ / λ) / [(K-λ ₀ ) SIN [N (K + 1 -λ ₀ / λ]] ² , where K is the number of the smaller of two consecutive spectral orders of the diffraction grating, λ ₀ is the wavelength at the maximum of the grating concentration in the 1st order of the spectrum, determine the wavelength at the maximum of the energy concentration. The method is useful for diffraction gratings having a maximum energy concentration in the ultraviolet and vacuum ultraviolet regions of the spectrum. 2 Il.

Description

This invention relates to optical spectral instrumentation.

The aim of the invention is to improve the accuracy.

FIG. I presents a diagram of the device for carrying out the proposed method; in fig. 2 is a plot of the transmittance ratio of the photometric wedge v / p versus the ratio of wavelengths.

An apparatus for carrying out the method comprises a source of monochromatic radiation, a photometric wedge 2, a diffraction grating under study 3, and a conical screen 4 for observing spectral orders.

FIG. 1 and 2 are designated: 5 - a bunch, reflected from a wedge; 6 — beam reflected from the grating in zero order; 7 - beam reflected by the lattice LT in the first order; 8 - dependence graph / Р К 0.

ABOUT)

about

SP

3149

This is done in the following way.

Illuminate with the help of the radiation source 1 the atomic wedge 2 and the studied recheck 3 with monochromatic radiation with the wavelength D, see beam 5 reflected from the wedge 2 on the conical screen, then the counters 3 are turned around the axis parallel to its FiTpHxaM until the beam 6 coincides reflected from the grating in the K-th order of the spectrum, with beam 5. By moving the wedge 2 in the direction of its density variation, the intensities are equalized by beam 5 and 6 and the density curve corresponding to the position equalizing the intensity of the beams 5 and 6. Then rotate the grating 3 around an axis parallel to its strokes until the beam 7, reflected from the grating 3 in K + 1-M order of the spectrum, coincides with the beam 5. By moving the wedge 2 they equalize the intensities of the beams 5 and 7 and by the graduated graph of the photometric wedge determine its density p,,

The wavelength Aj at the maximum of the energy concentration in the first order of the spectrum is determined from the plot of fk

Relation fK., T) (.T)

(K4-) sin nK + l-}

Ac

-; sLnLiKis.T I-

K is the number of the two consecutive spectral pores,. 40

- transmittance of the photometric wedge, corresponding to the equalization of the beam intensities: reflected from wedge 2 and from the studied grating 3 in the Kth and K + 1st order of the spectrum, respectively; AO wavelength at maximum energy concentration in the first order of the spectrum;

L - dpina wave monochromatic radiation.

The reflection coefficient of the grating in the Kth order of the spectrum F is determined by the expression

rf, G sin iLCbli V /) t (Y., j J

When measuring, the intensity I of beam 5 is determined by the intensity of the incident beam and the reflection coefficient of the surface of the wedge 2:

f - L o,

Intensity I

1g 0 1.

4 of the beam 6 is determined by the transmittance (wedge density 2) / and the reflectance of the grating 3 fz:

It I.PK to, at the time of equalization

 "FK

 }

from here

one;

Similar to Fich.

R..,

Since measurements are made at the same wavelength, then o (constant.

In this way .

 Г sin№- -) (), 1

m. (K - y-) sin (K + I -))

GK4

7

0

five

0

j

0

According to schedule 8, the dependence of f on for the ratio

Rk "1 / Pk find the ratio

J and then determine Lr.

The most useful and promising application of the method is for gratings that have the maximum energy concentration in the ultraviolet and vacuum ultraviolet spectral regions, for which it is practically impossible to use methods of qualitative visual determination due to a limited set of visually observed spectral lines, and quantitative photoelectric methods require the use of vacuum equipment.

Formulas and inventions

A method for determining the wavelength at the maximum concentration of the energy of a diffraction grating, including the illumination of the diffraction grating, with a monochromatic radiation beam, characterized in that, in order to improve the accuracy, the diffraction grating is illuminated by a monochromatic radiation beam through a photometric wedge, the diffraction grating is rotated

514

 -

the grating around the axis parallel to its strokes, to align the beam reflected from the photometric wedge with the beam of the studied spectral array of the diffraction grating, change the transmittance value of the photometric wedge to equalize the intensity of the aligned beams for two sequential orders of the spectrum, and the wavelength at the maximum of the energy concentration of the diffraction grating is determined from the plot of

BUT,

1М1 Г iHtt (Kl, 36) iSiilSl) П, 1 () з1пГТ (-) |

(,

LT

e K

Lv 6

the number of the smallest of the two after the first order of the spectrum of the diffraction grating;

the transmittance of the photometric wedge, which corresponds to the equalization of the intensity of the beams: reflected from the photometric wedge and the diffraction grating in the KM and (K + 1) order of the spectrum;

wavelength at the maximum of the lattice concentration in the first order of the spectrum; wavelength of a monochromatic radiation beam.

f x "

Phie.1

l you

5.0

18

XL

ff.5 FIG. 2

 0

Claims (3)

Claim A method for determining the wavelength at a maximum concentration of energy of the diffraction grating, including illuminating the diffraction grating with a monochromatic radiation beam, characterized in that, in order to increase accuracy, the diffraction grating is illuminated with a monochromatic radiation beam through a photometric wedge, the diffraction wedge is turned 5 1497605 grating around an axis parallel to its strokes, before combining the beam reflected from the photometric wedge with the beam of the studied spectral order of the diffraction grating, change the transmittance of the photometric wedge to equalize the intensity of the combined beams, register the transmittance of the photometric wedge for two consecutive orders of magnitude of the spectrum, and the wavelength at the maximum concentration of energy of the diffraction grating is determined by the dependence plot 15 Pk + 1G sintff (K- l ~ j ^) 1 ’ 7Г '("Χ, where К is the number of the smaller of two consecutive orders of the spectrum of the diffraction grating; p * is the transmittance of pho ^{1 of the} wedge corresponding to equalization of the beam intensity: reflected from the photometric wedge and diffraction grating in the Kth and (K + 1) -th orders of the spectrum; L0 is the wavelength at the maximum concentration of the lattice in the first order of the spectrum; A is the wavelength of the monochromatic radiation beam. "And ⁷ Fig! 1 497605