SU1543225A1 - Laser arrangement for measuring irrigularities of surfaces - Google Patents

Abstract

The invention relates to a measurement technique and can be used to determine flatness and non linearity. The aim of the invention is to improve the measurement accuracy. The radiation from lasers 2 and 3 enters the telescopic expanders 4 and 5, and then passes through polarizers 6 and 7, at the output of which monochromatic laser beams are formed, linearly polarized in mutually perpendicular planes. With the help of the beam splitter 8, the light beams are combined and fall on a double-slit diaphragm 9. The laser beam with a wavelength λ ₁ passes the analyzer 10 without attenuation and diffracts at the double-slit diaphragm 9. For a beam of wave length λ _{2, the} analyzer 10 is opaque. As a result of the diffraction of both light beams on the slits of the diaphragm 9 diffracted by the analyzer 10, two interference patterns of different colors are formed in the plane of the recording device 11. The displacement of the double-slit diaphragm 9 together with the polarizer 7 leads to a shift of the interference fringes in the plane of the recording device 11. Measuring the distance from the end point of the alignment to the central maxima of the interference patterns, the indiscriminate values are obtained. 1 il.

Description

The invention relates to a measurement technique and can be used to determine flatness and non linearity.

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

The drawing shows a diagram of the meter.

The meter contains illuminator 1, made of two identical branches including two lasers 2 and 3, two telescopic extenders 4 and 5, two polarizers 6 and 7, a beam splitter 8. mounted on the path of radiation from laser 3 at an angle of 45 to the optical axis, the length A, the radiation waves of laser 2 are different from the radiation wavelengths of laser 3, the optical axis of laser 3 is coupled by means of a light divider 8 to the optical axis of laser 2, polarizers 6 and 7 are set respectively during radiation from each of lasers 2 and 3 in front of the beam splitter 8 and oriented This means that behind the beam splitter 8 of the plane of polarization of the beams are orthogonal, a double-diaphragm 9, successively installed along the path of radiation from the laser 3, an analyzer 10, made in the form of a plane-parallel plate, the width of which is chosen such that it does not overlap part of the diaphragm 9 forms a two-body mark with dimensions that provide the condition for obtaining a diffraction pattern of laser radiation 3, the plane of maximum transmission of the analyzer 10 is parallel to the plane of polarization of the laser 3, the analyzer 10 and the two-body axis phragma 9 are mounted in the same plane, and a recording device 11

B,

to the plane of installation of the recording device 11;

and Aj radiation wavelengths of lasers 2 and 3;

and X Лз.- the width of the interference fringes obtained as a result of the interference of diffracting beams with wavelengths ft, and A The meter works as follows.

The radiations from lasers 2 and 3 enter the telescopic expanders 4 and 5, and then polarizers 6 and 7 pass, at the output of which monochromatic laser beams are formed, linearly polarized in mutually perpendicular planes. With the help of the beam splitter 8, the light beams are combined and fall on the double-aperture 9. The laser beam with a wavelength of 7 waves passes through the analyzer 10 without attenuation and diffracts on the double-sheath diaphragm 9.

For another beam with a D-wavelength of radiation, the plane of preferential oscillations of which is orthogonal to the plane of preferential oscillations of laser radiation with a length A, wave, the analyzer 10 will be opaque and affect the formation of an interference pattern in the plane of the recording device 11. Slight diffraction of the laser beam with a length fl Polarizer 7 waves will slightly change the energy distribution in the interference katin, however, the position of the bands will not be affected.

The dimensions of the two-body mark are determined from the ratios of kl foSt

a 37 + sT

a + b -.

e k - the number of interference minimum involved in the formation of interference patterns;

S, is the distance from the plane of installation of the laser 2 to the plane of installation of the double-aperture diaphragm 9;

So is the distance from the plane of installation of a double-cavity diaphragm 9

Due to the fact that the parameters of the two-body mark are calculated for laser radiation with a wavelength, the interference pattern in the installation plane of the recording device 11 will be contrasted. To achieve the same effect and for a different laser beam with a wavelength, it is necessary that the part of the diaphragm 9 is not blocked by the analyzer 10 to form a two-body mark, the dimensions of which must satisfy the ratio

,

and i-1.

2 S,

.

(2)

ten

51543225

performed by choosing a ShIR analyzer 10 according to

s; .- 21v. (h)

As a result of the diffraction of both vetlight beams on the slit of the two-body mark in the plane of the registering device 11, two internation paintings of different colors (ft, and 2) are formed.

F

c d d u s n l h h l l 15 l h w r r a r i r po p k

The displacement of the two-prong diaphragm 9 together with the analyzer 10 in the direction of one axis by an unknown controlled insolation value displaces the interference fringes in the plane of the recording device 11. Measure the distance from the end point of the alignment to the central maxima of the interference patterns, taking into account the effect of atmospheric inhomogeneities determined from the ratio

JAi-kiz) SI. g L

 lk: ± 22) si

yelg t

L,

Л4z measured distance from the end point of the alignment to the center-high interference patterns

dispersion difference.

five

6

Claims (1)

Invention Formula A laser metering gauge containing a laser and a two-body diaphragm sequentially installed along its radiation path and a recording device, characterized in that it is equipped with a coagulator mounted in the path of the radiation from the laser in front of the diaphragm at an angle of 45 to the optical axis, the second laser, the radiation wavelength of which is different from the wavelength of the first laser, set in such a way that its optical axis is coupled by means of a splitter with the optical axis of the first laser, two polarizers installed respectively during the radiation from each of the lasers in front of the beam splitter and oriented so that the beam polarization planes are orthogonal behind the beam splitter and the analyzer made in the form of a plane-parallel 0 five a plate whose width is chosen such that the part of the diaphragm which it does not open forms a two-shaft mark with dimensions that provide the condition for obtaining a diffraction pattern from: the first laser, the polarization plane of the maximum transmittance of the para. type filter, the polarity of the first type, the radiation of the first type, and the analyzer and the two-tail and the mark are installed closely to each other in such a way that their axes of symmetry coincide.