Abstract:The existence of particle cluster contaminants on the components of IR optical system not only changes the stray light radiation characteristics of the system

but also degrades the system signal to noise ratio. In this paper

the model for the distribution of particle cluster contaminants has been given. A Cassegrain telescope has been taken as a typical example and using the ASAP optical ray tracing software

the change of the system stray radiation and the contrast ratio between point objects and background has also been simulated before and after the primary mirror was contaminated. So as the effects of different cluster contaminants position on system radiation has been discussed. The results indicate that the existence of the cluster not only alter the system’s stray radiation properties

but also decreased the target-to-background contrast obviously. Further study shows that the position of contaminants cluster aggregation also effects more or less on the system stray light radiation and the contaminate of the mirror boundary has more effect than the centre. Therefore

in practical applications

the factional area coverage of particles on optical components should be strictly controlled and the mirror should be cleaned reasonably in time.