Optical feedback range finder for two-frequency laser based on Zeeman-birefraction

Abstract

Light-feedback distometer based on two-frequency laser with Zeeman-birefraction, which belong to laser ranging technology field. The distometer consists of light source, measuring section and signal processing section. Laser outside cavity is tuned to realize laser internal schema transformation and at the same time optical signal feedback detection is exert on laser. The difference of light intensity modulation depth between laser working on longitudinal bimodule and on monomode is relative to outside cavity length. When outside cavity length equals integer multiple laser cavity length modulation depth difference is minimum; when outside cavity length bias from integer multiple laser cavity length, modulation depth enlarges gradually.

Description

technical field [0001] An optical feedback rangefinder based on a Zeeman-birefringence dual-frequency laser belongs to the technical field of laser rangefinder. Background technique [0002] When the laser output light is reflected or scattered by external objects, part of the light will return to the laser cavity and mix with the beam in the cavity, causing the output light intensity of the laser to change. This phenomenon is called the optical feedback phenomenon (self-mixing interference) Or optical feedback. The phenomenon of light feedback was first reported by King in 1963. The optical feedback system is simple and compact in structure, and generally only consists of a laser and the object to be measured. The two basic characteristics of the optical feedback signal are: [0003] 1. Every time the external reflector or scattering object moves by half the wavelength of the light wave, the laser light strengthens a fringe; [0004] 2. The fluctuating depth of the frin...

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Problems solved by technology

If the optical feedback level is too low, there will be no mode hopping to make the measurement impossible

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