Application Of Phase Mask Techniques In Optical Imaging System

Phase mask techniques refers to inserting a phase mask at the aperture stop of an incoherent optical system,changing the wave-front shape at the pupil,modulating the wave-front and phase of incident optical-field at pupil,and finally using optical image processing to achieve computational imaging.With the rise of computational optics,there is a growing demand for imaging optics.Phase mask techniques provide a powerful complement to traditional optical imaging.This paper studies the related applications of phase plate techniques in optical imaging,including the depth of field extension of the visible imaging system,the athermalization of the infrared imaging system,and the anti-laser of the infrared imaging system.The details are as follows:1.The working principles of phase mask techniques are analyzed,including phase mask wave-front coding and decoding theory.The coding models of cubic phase plate,quintic phase plate and scroll phase plate are established.The decoding theory of image restoration is deduced.And the evaluation indicator of image restoration effect is put forward.2.The application of phase plate t techniques in depth extension of imaging system is studied.An optical system for visible band with F-number of 4.5,alignment plane distance of 1075 mm,and initial depth of field of 18 mm is designed.The designed quintic phase plate is applied to the imaging system to achieve ten times depth of field continuation.The experimental result is consistent with the theoretical result,which shows that the phase plate can achieve high quality imaging in a wide depth of field.3.The application of phase mask techniques in the athermalization of refrigeration infrared imaging system is studied.For 3.7 ?m~4.8 ?m in the infrared band,a cooled infrared imaging system with F number of 2 and high imaging quality at normal temperature is designed.By using a quintic phase mask to eliminate thermal defocus,the athermalization of the system in the temperature range of-40°C to +70 °C is achieved.4.The application of phase mask techniques in the field of anti-laser imaging is studied.Several laser-induced methods of the imaging system are analyzed and compared.By using the vortex phase mask,the laser-induced function for a cooled infrared imaging system is realized.The system not only can be well imaged,but also can reduce the incident laser power to 1/50.