Optimal F-Number of Ritchey–Chrétien Telescope Based on Tolerance Analysis of Mirror Components

Abstract

The Ritchey–Chrétien telescope has been the key optical module for remote sensing instruments (RSI), in which the root mean square (RMS) random surface wavefront error and the alignment error of the primary and the secondary mirror takes the highest weighting in the tolerance analysis for the fabrication and assembly of the telescope. Therefore, the higher tolerance of those items becomes preferable for higher efficiency of RSI manufacturing. In this paper, the correlation between those tolerance items and the f-number of the telescope has been investigated. Although the f-number is normally a system parameter well specified in the beginning of the design process, it is not very rigid in practice and has a certain amount of allowable range. The optimal f-number can then be chosen based on the consideration of those key tolerance items. The proposed concept can be generalized as a novel methodology of design for tolerance.

Keywords

• remote sensing instrument
• Ritchey–Chrétien telescope
• tolerance allowance
• RMS random surface wavefront error
• surface de-center error
• surface tilt error