Abstract

Pulsar detection holds significant value in spacecraft autonomous navigation, space-based time reference establishment, and space science research. The X-ray telescope is a crucial instrument for pulsar detection, and its focusing mirror—the most critical component—exhibits detection performance directly influenced by the film thickness uniformity. This paper proposes an off-axis biaxial rotation coating method and derives, for the first time, a theoretical model of film thickness distribution on a cylindrical substrate based on classical thin-film deposition theory. Using this model, we systematically analyze the influence of key coating parameters—namely the distances a and b from the evaporation source to the vertical rotation axis and to the horizontal rotation axis, respectively—on thickness uniformity. By optimizing the coating process parameters, the thickness uniformity on the cylindrical substrate is significantly improved. When parameters a and b are within certain ranges and satisfy a specific relationship, a film with thickness uniformity better than 1% can be obtained. Coating experiments are carried out on a mandrel cylinder, and the measured film thickness distribution shows good agreement with theoretical predictions, with a maximum deviation of only 1.2%, thereby validating the accuracy of the proposed model. This work provides a rapid, non-iterative approach for determining coating parameters, significantly improving efficiency and reducing costs.

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