Interferometric ranging device using coherent electromagnetic beams - uses two different frequencies for providing phase difference measurement

摘要

The ranging device uses two coherent electromagnetic beams to determine the spacing between two optical reflectors.a The beams exhibit two different frequencies, with measurement of the phase difference between these frequencies using a common zero print. The two frequencies can be switched around using a half lambda plate with a second phase difference measurement obtained. The two frequencies are optically separated via an optical system. Each beam is fed along the measuring path or a reference path a given number of times. USE - For accurate length measurement in sub-manometer range.