Research On Pollution Evaluation Method Of Space Optical System

Space contamination has a serious impact on the optical system on the spacecraft.Contaminants deposited on the surface of the optical system can reduce the light intensity transmission rate of the optical system,thereby reducing the performance of the entire optical system.The outgassing of spacecraft materials is one of the important causes of pollution.When there are many pollutants deposited on the surface of the optical system,light attenuation will occur.Therefore,the optical system must be analyzed for damage.The Cassegrain optical system is the most commonly used optical system for satellite optical communications.The analysis of the primary mirror and the secondary mirror is very necessary.This article will proceed from the above issues and complete the following research work:1.Aiming at the outgassing regularity and outgassing analysis of the space materials,the gas outflow mechanism of the materials is described.The definition of the outgassing characteristics of the spacecraft's materials is given.The test of the characterizing quantity is introduced.An in-situ test device for the outlet performance of multi-station materials was designed,the function and progress of the device were introduced,and the rules and trends of outgassing of space materials were summarized.2.According to the damage condition of the optical system,the damage classification is summarized,and the situation that the light energy decay contaminant dominates and the influence of the light attenuation attenuation on the optical surface reflectivity and transmittance are theoretically analyzed.An in-situ test device for multi-station material outgassing performance for damage assessment was designed to prepare optical substrates for damage assessment.The simulation experiment was performed under limited experimental conditions.The experiment of the damage effect of the optical system under the visible light range and the infrared light range was designed and completed.The experimental data were analyzed and fitted.The attenuation function relation between the mass thickness of the contaminants and the light intensity transmission of the optical system was obtained,and the database on the optical imaging of the toner contamination to the optical system was obtained.Finally,an equivalent analysis method using carbon powder as a standard material is proposed.That is,the mass thickness of other contaminant materials to be measured is converted into the mass thickness of the carbon powder,and the damage relationship of the carbon powder to the optical system is evaluated.Thus,the damage relationship of the contaminant material to be measured to the optical system is obtained.3.The theory of cavity contamination analysis was put forward.Taking thecommonly used Cassegrain optical system of satellite optical communication as an example,two kinds of pollution conditions that may be encountered by Cassegrain's optical system were summarized,that is,the pollution generated from the system's own gas outlet and passed.External contamination coming in from the tube mouth.A model was established based on the Cassegrain optical system to determine the mirror state of the next contamination analysis.The main idea is: Compute the space solid angle corresponding to the spatial pollution source of the mirror.Assume that the material outgassing material diffuses to the space 4? solid angle,and the solid angle ratio is the ratio of the contamination amount,so that the entire optical mirror contamination can be calculated.The total amount of material,and thus the mass thickness,was used to evaluate the optical damage.In this paper,the pollution assessment model of Cassegrain optical system is established,and the distribution of optical contaminant concentration is obtained through simulation.It provides a new analytical method for the assessment of pollution in spatial optical systems.