A WFOV long focus optical system of 70mm large frame hight speed camera is discussed. The optical system of the catadioptric structure is used in it for the first time. The problem that the offaxis image quality decreased too quick because of the large central stop caused by the wide FOV is successfully solved. The whole length of optical system ∑L0.6f′,offaxis MTF0.4 at N=30lp/mm are achieved.

RESEARCH OF OPTICAL SYSTEM WITH WIDE FIELD OF VIEW AND LONG FOCUS FOR 70mm HIGHT SPEED CAMERA

The theory for the design of optical systems corrected of secondary spectrum by using normal glasses is presented. The algorithm for the evaluation of secondary spectrum contribution on each surface is developed and applied to the design of optical systems. Two design examples are given.In both design examples the secondary spectrum is well corrected by using standard glasses only.

Correction of Secondary Spectrum Based on Normal Dispersion Glasses

Design of Apochromatism Objective Lens of Aerial Camera Based on Large Frame Array CCD

Spherochromatism of Hybrid Diffractive-Refractive Apochromatic Telescope Objectives

This paper designs a compact apochromatic lens with long focal length, which operates over very-broad spectrum from 400nm to 900nm for high resolution image application. The focal length is 290mm, and F-number is 4.5.In order to match CCD sensor, lens resolution must be higher than 100lp/mm. It is a significant challenge to correct secondary spectrum over very-broad spectrum for this application. The paper firstly pays much attention on dispersion characteristic of optical materials over this very-broad spectrum, and dispersion characteristic of glasses is analyzed. After properly glasses combinations and optimal lens structure selected, this compact apochromatic lens is designed. The lens described in this paper comprises fewer lenses, most of them are ordinary optical materials, and only one special flint type TF3 with anomalous dispersion properties is used for secondary spectrum correction. Finally, the paper shows MTF and aberration curve for performance evaluation. It can be seen that MTF of the designed lens nearly reach diffraction limit at Nyquist frequency 100lp/mm, and residual secondary spectrum is greatly reduced to less than 0.03mm (in the lines 550nm and 787.5nm). The overall length of this compact apochromatic lens is just 0.76 times its focal length, and because of fewer lenses and ordinary optical materials widely used, production cost is also greatly reduced.

Zhi Zhang

Papers

Design of compact apochromatic lens with very-broad spectrum and high resolution