CCD光敏面上规则点阵的产生机理

Formation mechanism of regular lattices on photosensitive surface of CCD

采用1064 nm激光辐照可见光面阵CCD时,在其光敏面上观察到了规则点阵,相邻格点的间距约为99.38μm。改变激光的入射参数发现,规则点阵的产生与激光的入射能量、束散角和入射角无关,而与激光的波长有关,532,632,670和780 nm激光辐照时均没有观察到规则点阵的出现。更换不同型号的CCD,像元尺寸由3.75μm增大为5.6μm,相邻格点的间距却由99.38μm减小为63.84μm。改变前置光学系统的F数、焦距和光路结构,相邻格点的间距均保持不变。通过采用高分辨率的折返镜头开展实验,发现点阵中的每个格点与CCD光敏面上的像元一一对应,并且实验测得的格点间距与衍射效应计算的格点间距最大偏差仅为1.18μm,证明了规则点阵是由于CCD光敏面的二维光栅衍射效应引起的。

The formation of regular lattices was observed on the photosensitive surfaces of visible-array charge-coupled devices(CCDs)irradiated using a 1064 nm laser.The pitch of adjacent lattices was ap⁃proximately 99.38μm and remained unchanged as the energy of the incident laser was increased.The ex⁃perimental results of changing laser-incident parameters revealed that the occurrence of the regular lattices was independent of the beam-divergence angle and laser incidence angle.Furthermore,lattices did not oc⁃cur when the center wavelengths of the laser were 532,632,670 and 780 nm.When irradiating experi⁃ments were performed on another type of CCD,the pixel size of the lattices increased from 3.75 to 5.6μm,but the pitch of adjacent lattices decreased from 99.38 to 63.84μm.The pitch was also independent of the F-number,focal length,and optical path structure of the front optical system.The results of the analysis using a catadioptric high-resolution optical system revealed a one-to-one correspondence between every lattice and pixel on the photosensitive surface of the CCD.The maximum deviation between the measured pitch and theoretical value was only 1.18μm.Moreover,the perfect consistency strongly proved that two-dimensional grating diffraction of photosensitive surfaces of CCDs resulted in the forma⁃tion of regular lattices.