SU1392364A1 - Interferometer for measuring large displacements - Google Patents

Abstract

The invention relates to a measurement technique, in particular, to interferometers for measuring linear movements of objects, and can be used to measure large alternating movements. The purpose of the invention — extending the functionality and improving the accuracy — is achieved by eliminating the ambiguity of determining the direction of movement and using an automatic system for adjusting the position of the first reflector. The laser 1, the beam splitter 2 and the reflectors 3 and 5 form a Michelson interferometer that measures the position of an object mechanically coupled to the reflector 5. A negative feedback system comprising a photoelectric converter 6, a negative feedback amplifier 8 and a piezo actuator 4, adjusts the position of the reflector 3 so as to reduce the constant difference of the optical lengths of the interferometer arms. Depending on the direction of movement, the sign of the signal in the negative feedback circuit changes and the counter of the 10 interference bands records the position of the object by calculating the difference in the number of positive or negative pulses. I Il. ABOUT)

Description

(54) MICHAELSON'S TYPE INTERFEROMETER FOR MEASURING LARGE MOVEMENTS (57) The invention relates to measuring technique, in particular to interferometers for measuring linear displacements of objects, and can be used to measure large alternating displacements. The purpose of the invention - '’expanding functionality and increasing accuracy - is achieved by eliminating the ambiguity in determining the direction of movement and using an automatic system for regulating the position of the first reflector. Laser 1, beam splitter 2, and reflectors 3 and 5 form a Michelson interferometer that measures the position of an object mechanically coupled to reflector 5. A negative feedback system comprising a photoelectric transducer 6, negative feedback amplifier 8, and piezo drive 4 adjusts the position of reflector 3 so to reduce the constant difference in the optical lengths of the arms of the interferometer. Depending on the direction of movement, the sign of the signal in the negative feedback circuit changes and the counter 10 interference fringes records the position of the object by calculating the difference in the number of positive or negative pulses. 1 ill.

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1392364 A1 poliointer.

The invention relates to measuring equipment, in particular to interferometers for measuring linear displacements of objects, and can be used to measure large alternating displacements.

The purpose of the invention is the expansion of functionality and accuracy by eliminating ambiguity. determine the direction [movement and use of the automatic [tichesky system of regulation

S to the first reflector.

The drawing shows a diagram; a Michelson-type ferrometer for rhenium of large displacements.

Michelson Type Interferometer for Measuring Large Displacements | contains a laser 1, a beam splitter 2 installed in series along its light beam, dividing the laser light beam into two beams, a first reflector 3 located in one beam and mechanically connected to the piezo drive 4, a second reflector 5 located in another light beam and having the ability to move along from this light beam, a photoelectric transducer 6, optically coupled to the output beam of the interferometer, a controlled switch 7, a negative feedback amplifier 8, a two-threshold comparator 9 and 10 etchik interference fringes.

A Michelson-type interferometer for measuring large displacements works as follows.

The measurement of displacement is as follows.

When the reflector 5 is moved along from the light beam (due to a change in the difference in the optical length of the interferometer arms, the intensity of the output light beam changes), the photoelectric converter .6 converts the change in light intensity into a voltage that is fed to the input of the negative feedback amplifier 8 through a controlled switch 7,

The output voltage from the amplifier 8 is controlled by a piezoelectric actuator 4, which moves the reflector 3 by an amount corresponding to the movement of the reflector 5. Thus, compensation is made for the change in the difference in the optical length of the arms of the voltage interferometer 20 to the triggering level;

1392364 2 ra. When the amplifier reaches the 8th output of the comparator, the 9th feedback loop is switched using the 7th switch. The voltage at the output of amplifier'8 disappears and reflector 3 returns to its original position, and switch 7 reconnects the input of amplifier 8 to the photoelectric converter. With further movement of the reflector 5, the compensation cycle is repeated, only each time after opening the negative feedback loop, the compensation is resumed with a different value of the difference in the optical length of the arms of the interferometer. The voltage at the output of amplifier 8 is in the form of a sawtooth pulse. The polarity of these pulses depends on the direction of movement of the reflector 5, since when the direction of movement of the reflector 5 changes, the polarity of the voltage at the output of the amplifier 8 changes. The comparator 9-. Has two thresholds, the levels of which are selected from the condition of ensuring movement in each direction of the reflector 3 by an amount exceeding 1/2 of the wavelength by laser radiation 1. Counter 10 calculates the difference in the number of positive and negative pulses. According to the meter readings, the amount of movement of the reflector 5 is determined

Claims (1)

Formula and acquisitions like Michelson. An interferometer for measuring large displacements, comprising a laser, a beam splitter installed along the laser light beam and dividing the light beam into two beams, a first reflector installed along the first light beam, a second reflector installed along the second beam, a photoelectric converter, and an interference stripe counter , characterized in that, in order to expand functionality and improve accuracy, it is equipped with a piezo drive, a negative feedback amplifier controlled by a commutator rum and a two-threshold comparator, while the piezoelectric actuator is mechanically connected to the first reflector and connected to the output of the negative feedback amplifier, the input of which is connected to the photoelectric converter through the managed switch, the input of the two-threshold comparator is connected to the output of the controlled switch, the output of the two-threshold comparator is connected to the output of the negative amplifier feedback, and the counter of interference fringes is connected to the output of the negative feedback amplifier.