SU1427168A1 - Interferometer - Google Patents

Abstract

The invention relates to a measurement technique, namely to interference dilatometers, and can be used to measure the change in the size of solids under the effect of temperature. The purpose of the invention is to improve the accuracy in dilatometric measurements. The beam from the source 1 of monochromatic light is converted by a collimator 2 into a narrow parallel beam of light and fed to the beam splitter 3, reflected at an angle of 90 and placed on the beam splitter 4 designed to accommodate the test sample 8, half of the upper surface of which contains a specular reflective layer 9. On splitter 4 two beams are formed. One beam passes the beam splitter 4 and the corner reflector 5 of the tetrahedron type, hits the reflective mirror layer 9 of the beam splitter 4, returns the same path and, together with the second beam reflected from the beam splitter 4, hits the beam splitter 3, then both beams are reflected from light 3, directed to a dilated thin lens of the plane of the photodetector 7, create an interference pattern. 1 il. L ss with:

Description

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The invention relates to a measurement technique, namely to interference dilatometers, and can be used to measure the change in the size of solids under the effect of temperature.

The purpose of the invention is to improve: e accuracy with dilatometric measurements and x.

i The drawing shows the principle Ma scheme of the interferometer. ; The interferometer contains monochromatic light source 1 in series — a laser, a collimator 2, a beam splitter 3 for dividing the radiation into two branches, one of which has a beam splitter 4 and a corner reflector 5 of tetrahedral type, and the other 6 has a lens 6 and a photodetector 7 .

: The beam splitter 4 is intended for (securing the test sample 8, | on half of its surface applied (specular reflective layer 9.

The proposed interferometer works as follows.

The beam from source 1 of monochromatic light is converted by a collimator 2 into a narrow parallel beam of light and fed to a beam splitter 3. Then the beam is reflected at an angle of 90 and falls on beam splitter 4, which forms two beams. One beam passes through the beam splitter 4 and the corner reflector 5, hits the reflective mirror layer 9 of the beam splitter 4, returns the same path and, together with the second beam reflected from the beam splitter 4, hits the beam splitter Zo Then both beams are reflected from the beam splitter 3, On the expanding lens of the plane of the photodetector 7, they create an interference pattern.

The test sample 8 is placed on both halves of the surface of the splitter 4 so that the axial lines of the sample 8 and splitter 4 are the same.

When changing the length of the sample 8 under the action of temperature, the overall stroke of the working beam between the beam splitter 4 and the corner reflector 5 changes, as a result of which the interference pattern patterns move.

The movement of one interference band is caused by changing the length of the sample 8 by 1/4 (A is the length of

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laser radiation), since in the scheme under consideration, the overall stroke of the working beam is increased to four times the length of sample-8.

The photodetector 7 senses the movement of interference fringes and generates signals for their subsequent counting.

The corner reflector 5 has the property to change the angle of reflection of the beam and to keep its overall stroke unchanged. In addition, due to the mirror splitter 9 of the splitter 4, the working beam is reflected in the opposite direction to the corner reflector 5. In the case of the working beam reflected at an angle close to 90 °, the reflected beam maintains parallelism to the direct working beam and, returning in the same way, interacts with the original beam, the passage of the PC through the beam splitter 3 and reflected from the beam splitter 4, forms the interference pattern, which the photodetector 7 forms into signals.

When the sample 8 is twisted, the angled reflector 5, which rotates together with the sample 8, does not change the exit point and exit angle of the working beam, and thus the overall stroke of the working beam remains unchanged, thereby eliminating measurement error.

Thus, the bending and torsion of sample 8 does not affect the overall beam path, i.e. working path vector,. consisting of a series of segments remains unchanged.

Claims (1)

0 claims An interferometer containing a sequentially installed source of mono-, chromatic light, a collimator and a beam splitter for separating radiation into two branches, one of which has a beam splitter and an angular reflector, a. in the other branch there is a lens and a photodetector, characterized in that, in order to increase accuracy in dilatometric measurements, a beam splitter installed in one of the branches is designed to fix the test sample, a specular reflecting layer is applied on half of its surface, and the beam splitter is positioned so that this surface is surrounded by 1: (en to the corner reflector.