Optical Design Of Two-steps Zoom System Under Visible Light For A Certain Theodolite

Though infrared system and continuous zoom system have been used more and morewidely in military, space, photography and many other fields, to research discontinuouszoom system(two-steps) under visible light still has the important practical value.There finished an two-steps zoom system of long focal length and of large apertureunder visible light for a certain theodolite，and used the design idea of modularization, whichthe overall system was divided into three subsystems to design independently then composedtogether At first, the design requirements were computed from parameters of detector Then,the design idea was decided by analyzing the design requirements. And then, the originalstructure was selected according to the design idea, so that the subsystems could be designedindependently. At last, they were composed together to finish the overall system.During the design process of the overall system, re-imaging and afocal system wereused, in order to reduce the diiffcult while designing, as well as to make it more convenientwhile assembling, testing and debugging. The subsystems covered not only reflecting andcatadioptric system, but also zoom system of moving and of switch, all of them weredesigned according to equation for eliminating aberration or formula for computing originalstructure. The performance difference between two different structure was analyzed followedthe design result by comparing some particular data. At last, there was a summary of thedesign，and some inadequacy was pointed out as well as the further research direction.