Interferometer

The interferometer, or laser interferometer, is a measuring device based on the principle of interference. It is used to measure distances with the highest possible precision. For this purpose, a monochromatic laser beam is split into a measuring beam and a reference beam at a semi-transparent mirror. These two beams are reflected by one reflector each, one fixed and one movable. The reflected beams are superimposed on the semi-transparent mirror, creating the interference fringes that give the system its name, which lie across the receiver and are analyzed by it. When the reflector attached to the target is moved, a periodic signal is generated at the receiver. This is then evaluated with the aid of counters, whereby the measuring range is determined by the counter range. By arranging two detectors, the direction of movement can also be determined. Using mathematical formulas, it is possible to precisely analyze changes in light intensity due to changes in the distance of the measured object and calculate the degree of displacement. Specialized interferometers make it possible to achieve measurement ranges of up to more than 10 m with resolutions of fractions of a half wavelength.