Study On Measurement Of Laser Active Target Tracking Angle

Angle measurement active laser tracking technology can quickly get the accurate angleinformation of the laser signal reflected or emitted by the moving target, so it is widelyused in free-space laser communications, laser navigation, laser guidance, and otherfields. In this thesis, the four-quadrant laser angle measurement technology is studiedand a circuit of the four-quadrant angle measurement tracking system is designed fordynamic target tracking measurements. After testing, we can achieve a fast real-timemeasurement of the azimuth and pitch angle of the moving target in the space by thecircuit we designed.The main contents are as follows:1. Laser dynamic tracking angle measurement techniques were analyzed andsummarized. Technologies of laser tracking angle measurement using CCD, PSD andfour-quadrant detector are analyzed respectively. After comparing the three detectingtechniques, we choose to utilize a four-quadrant detector for angle measurement of atarget moving fast in the space.2. The operational principle of the four-quadrant detector is analyzed. And we chooseto utilize addition and subtraction algorithm to calculate the central position of the laserspot and then to obtain the azimuth and pitch angle of the moving target. The mainelements which influence the positioning accuracy are also analyzed.3. A circuit for the laser tracking angle measurement system based on aOSQ-1000APD four-quadrant detector is designed. The detector’s output electricalsignal is amplified by a two-stage amplification circuit in our design. And the amplifiedsignal is then conversed to digital form by a10bit AD. Finally an AVR single chipmicrocomputer (SCM) is used for data processing and serial communication with thecomputer.4. The circuit for the four-quadrant detector laser tracking angle measurement systemis tested experimentally with a optical system of a300mm focal length. Progressing thepolynomial curve fitting and the error curve by experimentally measured data, then correcting software with comparing the curves, finally, with the distance of3.5mbetween the cooperative target angle measuring system target, and move within rangeof±1mm, angle measurement circuit for cooperative target has the position resolutionof30μm, the angular resolution of four-quadrant laser angle measurement systemreaches1.8"（~8.5μrad）.