Laser frequency discrimination device and frequency discrimination method based on Mach-Zehnder interferometer

Abstract

The invention discloses a laser frequency discriminating device and frequency discrimination method based on Mach-Zehnder interferometer. The device comprises three reflectors, four special prisms of different shapes and sizes, a quarter of a wave plate, a triangular prism, a one dimensional piezoelectric displacement table, two Wollaston polarizers, two converging lenses, and four unit detectors. It is possible to divide single longitudinal mode or multi-longitudinal-mode parallel laser beams which are slightly different in frequency and are formed by two successive impingements into four beams of emitted light which vary from each other due to the different frequencies of the incident light. After that, the four unit detectors detect the energy of emitted light from each beam. And the frequency difference between two times of the incident light can be inverted when the energy of four channels corresponding to the two times of incident light is found out. With a compact structure, fine path difference, the optical path difference of the device can be coarsely or finely scanned for high probing precision. It can be used for multi-longitudinal-mode laser impingement and has low requirements on detectors. It is particularly suitable for various vehicle-mounted or machine mounted Doppler radar frequency discrimination systems based on mobile platforms.

Description

technical field [0001] The invention relates to a laser frequency identification system, in particular to a laser frequency identification device and a frequency identification method based on a Mach-Zehnder interferometer. Background technique [0002] Doppler lidar is often used to measure wind speed or the moving speed of hard targets. It is widely used in atmospheric physics, meteorological remote sensing, and military weapons. The Doppler frequency shift device used to measure light is one of the most important applications in these applications. An essential core part. Currently, there are two types of detection methods used by Doppler lidar worldwide, coherent detection and non-coherent detection. Incoherent detection is also called direct detection. Direct detection is divided into edge detection technology and fringe imaging technology. Edge detection uses narrow-band filters to identify the frequency shift of the laser caused by wind speed or moving targets. Fring...

AI Technical Summary

Problems solved by technology

Incoherent detection is also called direct detection. Direct detection is divided into edge detection technology and fringe imaging technology. Edge detection uses narrow-band filters to identify the frequency shift of the laser caused by wind speed or moving targets. Fringe imaging uses F-P interferometer, Fizeau Interferometer, Michelson interferometer or Mach-Zehnder (Mach-Zehnder) interferometer's interference fringe and frequency correspondence to identify the frequency difference between the transmitted light and the received echo to invert the wind speed or the moving speed of the moving target. Both technologies can work normally under normal working conditions and each has its own advantages. However, once the system is to be placed on a mobile platform such as a vehicle or even spaceborne, the two technologies are both too complex and bulky, and the structure is not stable enough. Photodetection is a single longitudinal mode laser, some devices require constant temperature conditions and other issues

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