Distance meter

摘要

The meter has a laser source, a collimator and a Fabry-Perot etalon which, as a component of an oscillator circuit, generates optical pulses which, reflected or scattered by an object (5), are picked up by a null-indicator, converted into electrical signals and, if the sum of the delay time tv and propagation time tr of the pulses has a specified value to, provides a null signal to a voltage regulator. The regulator then controls the dc voltage applied to the etalon so that, for any measured length, the receiver is tuned to a null level, the dc voltage being representative of the length measured. A comparison channel with receiver (10) and filter (10.3) which is a null indicator, converts the optical pulses reflected to the etalon into electrical signals and, if the delay time tv of the pulses received is null or has a specified value, provides a null signal. The unit comprises a sinusoidal laser source (1), frequency modulated by an oscillator (8), a collimator (2) and a Fabry-Perot etalon (3) which generates optical pulses, the phase position of which is determined by the dc voltage applied to the etalon.