Spectral Detection And Signal Inspection In Laser Reconnaissance

The paper put forward a new method to determine the wavelength of incident laserbeam. A set of measuring system is successfully designed which is used to detect theincident laser's wavelength.Based on the different spectral response curves of InGaAs and Si photo-detectorand signal processing techniques, the paper realizes a novel method to syntheticallymeasure the incident laser's wavelength.The paper gives the theory analysis of the spectral detection method. Under thistheory, a set of spectral detection experiment system is set up. The system includesoptical setting, wavelength measuring system and photo-detector temperature controlsystem. Optical system is used to produce the homogeneous light within 400-1 800nmwidth wavelength band. Through sampling and computing the photo-detector's current,wavelength measuring system gets the wavelength of the incident laser. Because thephoto-detector's dark current is largely dependent on the environment temperature, thephoto-detector temperature control system is designed to keep temperature of the twophoto-detectors stable, which ensures the precision and reliability of the measuringresult. Whole detection system is controlled by personal computer, which is easy tooperate.Using this spectral detection experiment system, 500~4 lOOnm spectral band widthdetecting experiment is accomplished. Experimental result shows that the measuringresult is independent of the incident laser's direction and intensity. Compared with usualway to measure wavelength, such as F-P cavity, it is independent on the direction ofincident laser beam, what's more, it is short in response and simple in construction, themeasuring error is less than 2Onm.By changing the structure of optical fiber coupler and using other type of photo-detector, the method can be extended to measure laser's wavelength in 3'~? 1~t m or 8'?12 i~ m wavelength band easily.