Abstract: When a light beam goes through the space flooded with passive disturbing materials,such as heavy smog,water-fog,aerosol etc.,the light wave will be greatly attenuated.We call the space the strong attenuation field.Our aim is to get the information of the small grains of 0.001mm size,but a conventional vedio camera can not take the clear pictures of the grains of the disturbing materials from the field,and can not provide the information about the parameters of single grain and the statistical characteristics of the group of the grains.In our system,the combination of CCD display technique and a special optical system named image pick-up microscopy,like the optical system of a microscope,is used to enlarge the image of the gain in the field.Then the picture can be transmitted over a long distance to process and to obtain the information of the characteristics of the grains.In this paper,the aberration of the optical system and manufacturing tolerance of the optical system have been analyzed.This is a new method to measure the passive disturbing materials in photoelectric countermeasure.