Reserch And Implement Of The Laser Spot Detection In ATP System

Wireless laser communication(Wireless Laser Communication,WLC)is a kind of communication mode which uses laser as a carier to spread information.It has a lot of advantages,such as large capacity of communication,strong anti-interference ability,set up flexible,no license radio spectrum,but owing to the WLC system uses laser as the carrier which divergence angle is minimal and beam is very narrow.In addition,the effect of the atmospheric turbulence and platform jitter which leads to beam drift and laser spot dithering,Need a capture,Tracking and tracking(Acquisition,Tracking and Pointing,ATP)system is needed to establish a communication link and make sure the link is open.Laser spot detection technology is a key technology of the ATP system,the method which has strong anti-interference performance and good robustness could shorten the acquisition time and improve the tracking precision effectively.The main work accomplished in this paper is:(1)A new kind spot detection scheme of ATP system is designed.Using front-end CCD camera to complete the initial capture,beam after cassegrain telescope receiving need to be divided in two parts by the dispersion prism,one of the beam imaging on frosted glass screen.The back-end CCD could detect the position of laser spot on screen to complete beam fine tracking.(2)This paper proposes the corresponding image processing program according to the characteristics of laser spot detection system.For the capture detector,making the background noise template of gaze terminal to identify the target spot;In fine tracking stage,this paper using circle fitting algorithm to fitting standard circle,the zero and radius of laser spot can be accurately calculated,because of the shelter from secondary mirror,we need to detect the position of irregular laser spot coordinate through the feature extraction and parameter dimensionality reduction.(3)The software framework system and the software realization of image processing algorithm is completed,and the system carried out several field experiments to ensure the stability of the algorithm and system.Finally,the paper gives the image of laser spot after processing in different stages,in 1.3 km experiment,recognize the target spot from complex background noise intensity,and the error signal in the horizontal and the pitch direction in different time is extracted successfully,the distribution of laser spot position coordinates is presented,realize the function of automatic acquisition,pointing and tracking.