Co-alignment of detectors in dual-channel spectrometers by optical coherence tomography

Abstract

This work presents a method for detectors co-alignment in dual-channel spectrometer using optical coherence tomography. The method is proposed for the ELOIS (Enhanced Light Offner Imaging Spectrometer) developed by the AMOS company (Advance Mechanical and Optical Systems). This company designs and builds optical components and instruments related to the space industry and one of their current project is the ELOIS instrument.

A crucial aspect in the development of the instrument is the correct alignment of the focal plane assembly components. During this phase, the two detectors of the spectrometer need to be correctly co-aligned with each other in the six degrees of freedom. This work presents a method using optical coherence tomography for the co-alignment of the detectors in tip, tilt and focus.

The first part explains the theoretical aspects of optical coherence tomography and how it can be applied to the ELOIS instruments. The second part is the application of optical coherence tomography on a test bench replicating the components of the ELOIS. The procedure is detailed for this experimental test and an explanation of the results demonstrates the accuracy achievable with this method. The third part of this work explains the differences between the experimental test and the ELOIS instrument. The procedure of co-alignment and the achievable accuracy are detailed in the case of this specific dual-channel spectrometer.