Design Of A Continual Zoom Objective With High Speed

Compared with fixed focus lenses, zoom lenses have variable magnification without adjusting their position so that they can image with different resolution and enhance effectively their target detection efficiency. It is difficult for the current zoom lens to be used as the fore objective of high resolution hyperspectral imagers, because of its low speed and imagery non-telecentricity that should result in their low collection power and then low spectral resolution and signal-to-noise, and their pupil mismatch. To this end, study on high speed and imagery telecentric zoom objectives is carried out in this thesisIn the first chapter, the significance of this issue is introduced and the development of zoom lenses is reviewed.In the second chapter, at first, the concept, category and comparison of zoom systems are introduced. Then, based on the performance requirement of our developed hyperspectral imager, the structural type suitable for its zoom fore objective is analyzed and selected. At last, Gaussian optical analysis of the chosen mechanical compensation zoom system is presented.In the third chapter, solution for initial structure parameters of the zoom fore objective is given. First, its power is distributed among its lens groups. Second, their basic aberration parameters P and W are solved with our developed program. Third, the structural parameters, including the lens number, the distributing power, and the P and W value of singlet and cemented doublet, of each group are determined through resolution of its P and W values. Finally, the initial layout of mechanical compensation zoom objective is calculated with the above method.In the fourth chapter, according to the mentioned way in the preceding two chapters, mechanical compensation zoom lenses without and with a changing root are designed. Its optimization method, optimized result,cam curve, and imaging quality are given. The designed systems have the adventages of high relative aperture, structural compactness, imagery telecentricity, even illumination on image plane, and excellent imaging quality.In the fifth chapter, based on the structural feature of the designed zoom lenses, their tolerance is analyzed and distributed optimally for facilitating its fabrication.In the last chapter, the work and the innovation points are concluded and further researches prospected.