A device for counting fringes produced by an interferometer. An interferometer with a single photomultiplier is used to determine the magnitude and direction of motion of an object to a digital sensitivity of one-eighth of a wavelength. By an electronic squaring technique the digital sensitivity of the device can be increased to one-sixteenth or one thirty-second of a wavelength.
The invention relates to optical connecting systems for accurately positioning a surface with respect to another surface. The contacting system according to the invention comprises a Michelson interferometer in one arm of which an optical length modulating device is introduced. The source of radiant energy has an emission spectrum including two distinct spectral portions which are seperately sensed in the detection arm of the interferometer. The detected signals are superimposed at the input of a synchronous detector, the output of which is coupled to a zero indicator. The contacting devices in accordance with the invention are used in laser metrology systems.
The distance-measuring apparatus utilizes an interferometric technique to measure the distance to a light-reflecting surface. A laser-generated plane wave is split by a beam splitter into first and second plane waves. The first plane wave is directed to the reflecting surface which reflects it back to the beam splitter. The second plane wave is directed to a reference mirror which reflects it back to the beam splitter where it combines with the reflected first plane wave to form a combination plane wave. The combination plane wave is caused to vary periodically in amplitude by modulating the position of the reference mirror. Changes in the distance to the reflecting surface are obtained by electronically processing the changes in the power of the combination plane wave.
An interferometric distance measurement method which utilizes a sequence of at least two closely spaced optical wavelengths in order to achieve ambiguity resolution during the measurement procedure. In so doing, this method performs the equivalent of measuring distances at a relatively long wavelength by measuring the phase difference at two closely spaced optical wavelengths and computing the effective phase measurement at a wavelength which corresponds to the frequency difference between the two optical wavelengths measured.
A method and device for sensing changes in separation of a first member relative to a second member, as well as variables causing such changes is disclosed. Electromagnetic waves diffracted by means included in said first member interact with waves from means included in said second member to form a characteristic interference pattern. Measured changes in this pattern allow determination of changes in separation.
A semiconductor laser light modulation and demodulation system to be used in light communication system is realized. In the modulation system, strength modulated pressure wave or electromagnetic wave is directly applied to an active region of a semiconductor laser element and the frequency modulation is effected by varying an effective length of a laser resonator formed by the element. In the demodulation system, modulation signal is derived by an interference of the received laser light by splitting and then joining together after passing an interferometer having different path length arms.
