A large field laser scanning system is designed for PID imaging system. According to different deflectors, scanning
system methods have optical lens scanning system, polygon mirror scanning system, acousto-optic scanning system and
holographic scanning method. To realize large field scanning, a polygon mirror is used as scanner, which has high
scanning speed, high resolution and contrast, good gamma characteristic and F-θ lens system is used as focusing system
in type of scanner before lens. F-θ lens is special lens with linear scanning characteristic. F-θ lens can focus laser beam
and make linear scanning. The scanning performance of F-θ lens is usually decided by its focusing characteristics.
Designed system can scan object in 356mm length and the resolution achieves 35μm. Ball bearing guide screw system is
used to realize scanning in Y direction, the scanning length can be set according to request. Thus, the system can make
two dimensional scanning. By evaluating performance of optical system, the system focusing characteristics had
achieved the diffraction limit in entire field and satisfies the system's requests. Experiment has been carried on to test the
F-θ optical focusing system. The experimental results show that diameters of focusing facular at all view field are
approximately 35μm, which is identical with theoretical parameter and conforms to F-θ characteristic.