Small Laser Scanning System For Airborne Laser Communication

Point-to-point connection improves laser communication's confidentiality,but also makes the optical alignment more difficult.Based on Risley prism,a solution with scanning and tracking functions was proposed aimed at airborne laser communication system's dynamics.The main contents include:1.Design of system scheme.Specified system's emitting,receiving and scanning module.Introduced the procedures when system works independently or not which can conduct scanning,tracking and communicating in 40°×40° field.2.Design of emitting module.Based on the linear relationship between the illumination integral of an ideally uniform light spot in radial direction and its radius,the quadric surface was optimized.Using the designed optical model with 10.5 mm in length,the divergence of outputting beam with 1064 nm wavelength reaches to 6.9 degree with uniformity better than 81%and utilization higher than 85.3%.3.Design of receiving module.Receiving lens was designed with built-in stop which has ±13° linear field,9 mm aperture and 5 km working distance.Verified the spot's size and uniformity by comparing the encircled energy curve with parabola at round aperture and straight line at slit respectively.4.Common-path optical design and analysis of scanning pattern.Combined the optical axis of emitting and receiving module with rhombic prism.Analyzed the prism's impact on QD spot and emitting fiber.Corrected the Risley prism distortion by 75%via homograph compared with original result.Compared the scanning pattern at different scanning speed and direction.5.Mechanical design and system assembly with performance testing.Built up the driving structure by Brushless DC-Servomotor and magnetic grid coder.Designed the mechanical structure of emitting and receiving module with 117x119x151mm overall system size.System's pointing accuracy is ± 1.5°in test.