Molecular contamination on optical surfaces is a serious issue for space payloads. For ultraviolet (UV) payloads, molecular contamination results in loss of throughput. Whereas, for visible (VIS) payloads loss of throughput due to molecular contamination is not very critical. However, UV photopolymerization of molecular contamination can create serious problems to VIS payloads with stringent scatter requirements. Visible Emission Line Coronagraph (VELC) on board ADITYA-L1 mission is one of them. For such payloads, quantifying the effect of molecular contamination in terms of scattered light is very critical. To do the same, UV exposure studies are carried out on optical surfaces with different levels of molecular contamination. Contamination levels are defined by the weight and mass loss of the contaminant. UV dosage levels on the optical surfaces is determined by the number of hours of UV exposure and UV irradiance levels. Variation in the scatter from the optical surfaces is measured pre and post UV exposures. Contaminated optical samples are exposed to the UV radiation levels equivalent to 125 days of mission life. Substantial increase in the scatter of the contaminated samples is observed due to the UV exposure. Increase in scatter is more rapid in the initial mission days (up to 45 days). This paper elaborates the experiments carried out and discusses the results from them.

对于空间有效载荷，光学表面上的分子污染是一个严重的问题。对于紫外线（UV）负载，分子污染会导致通量损失。而对于可见光（VIS）有效载荷，由于分子污染而导致的吞吐量损失不是很关键。但是，分子污染的紫外线光聚合会给具有严格散射要求的VIS负载造成严重问题。ADITYA-L1任务上的可见发射日冕仪（VELC）就是其中之一。对于这样的有效载荷，根据散射光量化分子污染的影响非常关键。为此，在具有不同水平的分子污染的光学表面上进行了紫外线暴露研究。污染水平由污染物的重量和质量损失定义。光学表面上的紫外线剂量水平由紫外线暴露小时数和紫外线辐照度水平决定。在紫外线暴露之前和之后，测量来自光学表面的散射变化。被污染的光学样品暴露在相当于任务寿命125天的紫外线辐射下。由于紫外线的照射，观察到受污染样品的散射显着增加。在初始任务日（最多45天）中，散布的增加更快。本文阐述了进行的实验并讨论了实验结果。由于紫外线的照射，观察到受污染样品的散射显着增加。在初始任务日（最多45天）中，散布的增加更快。本文阐述了进行的实验并讨论了实验结果。由于暴露在紫外线下，观察到受污染样品的散射显着增加。在初始任务日（最多45天）中，散布的增加更快。本文阐述了进行的实验并讨论了实验结果。