SU364838A1 - LINEAR MOVEMENT OBJECT SENSOR - Google Patents

Description

one

The invention relates to the field of instrumentation technology and can be used in linear displacement sensors based on the use of interferometers, and can be used in highly precise equipment of the microelectronic industry.

A linear displacement sensor is known, based on the reading of interference bands B by a Michelson interferometer, comprising a coherent radiation source, a beam mixer, an optical system, photodetectors, and a pulse counter.

In this sensor, the light beam is split into two using a beam-splitting mirror, one of which is directed onto a fixed mirror and the other onto a mirror mounted on an object, the linear movement of which is measured. Movable and fixed mirrors perform the role of a beam mixer.

After reflection from the mirrors, the rays meet and interfere. In the zone of interference, a photodetector is fixedly mounted, producing current pulses, the number of which is proportional to the displacement. The emulsions are fed to a counter that generates information about the movement of the object being measured. In order that the linearity of the guides along which the object moves does not affect the accuracy of the measurement, the mirror mounted on it is made in the form of a prism in combination with a fixed fixed mirror (cat's eye system).

The disadvantage of this system is that the light beam passes the measured interval four times, which increases the measurement error due to deformations of the interferometer body, and increases the requirements for light coherence.

The purpose of the invention is to improve the measurement accuracy and reduce the requirements for coherence of light.

For this purpose, the beam mixer is made in the form of a dihedral mirror and two lenses installed so that the lenses focus the radiation at the top of the dihedral mirror. Two lenses, a dihedral mirror, and photo-detectors are designed to be fixed to each other on the object.

Chertelche depicts the optical scheme of the proposed sensor.

The sensor contains a source of coherent radiation /, a prize, we are 2 and 3, a beam mixer consisting of lenses 4, 5, and a dihedral mirror

6, the photodetectors 7 and the pulse counter 8. The sensor operates as follows. Rays of light a and b from a coherent radiation source, e.g. a laser, are directed by prisms 2 and 3 parallel to the displacement of the measured object to lenses 4 and 5, respectively. The lenses 4 and 5 focus the rays near the top of the dihedral mirror 6, which has such an angle at the vertex that the rays intersect in the plane of the photodetectors 7. The lenses 4 and 5, the dihedral mirror 6 and the photon detectors 7 are fixed fixed relative to each other and mounted on an object whose linear non-confusion is measured. When the measured object turns, due to the indirectness of the guides, which it moves, the angle of reflection of rays a and b from the dihedral mirror 6 will change, however, since the rays are reflected from the same mirror, the angle between the rays will not change. Therefore, the width of the interference fringes .so.kranits. This system is insensitive to a large extent to the object displacements in the direction perpendicular to the measured displacement, since the photodetectors

7, lenses 4, 5 n the mirror 6 are mounted on the object itself, and there is no change in the difference in the path of the rays to the point of their interference on the surface of the photodetectors.

Subject invention

An object linear motion sensor containing a coherent radiation source,

a ray mixer, an optical system, photodetectors and a pulse counter, characterized in that, in order to improve measurement accuracy, the ray mixer is made in the form of a dihedral mirror and two lenses installed so that the lenses focus the radiation at the top of the dihedral mirror, lenses, a dihedral mirror and photodetectors are designed for installation, they are fixed on the object relative to each other.

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