Metrology inside a cryostat using a cutting-edge periscope

Adrien Girardot; Jean-Emmanuel Mignau; Edgard Renault; Magali Loupias; Aurélien Jarno; Alban Remillieux

doi:10.1117/12.2673663

15 August 2023 Metrology inside a cryostat using a cutting-edge periscope

Adrien Girardot, Jean-Emmanuel Mignau, Edgard Renault, Magali Loupias, Aurélien Jarno, Alban Remillieux

Proceedings Volume 12618, Optical Measurement Systems for Industrial Inspection XIII; 126180J (2023) https://doi.org/10.1117/12.2673663
Event: SPIE Optical Metrology, 2023, Munich, Germany

Abstract

The PIC (Photogrammetry Inside Cryostat) is a cutting-edge periscope designed to be used during the prototyping, testing and alignment phase of HARMONI, one of the first-generation instruments of the Extremely Large Telescope. The challenge posed by operating the HARMONI instrument at a temperature of 130 K required the development of different non-contact measurement techniques to qualify optical and mechanical parts without touching them. Photogrammetry is a non-contact measurement technique, but it needed to be adapted to be used in a cryostat; this led to the development of the PIC. The periscope consists of a combination of six lenses, two mirrors, and three motorized degrees of freedom (the whole is mounted upside down on the lid of the test cryostat at CRAL in Lyon) and work together with an external camera to capture images at various angles. This is essential for obtaining accurate photogrammetric measurements. The motorized rotation systems allow for precise and controlled movements, and the combination of lenses and mirrors ensure that the images captured by the external camera are of the highest quality. The goal of the PIC is to obtain an accuracy of 25 μm + 5 μm, making it an essential component of the HARMONI tools and a major advancement in cryogenic photogrammetry.

Conference Presentation

Citation Download Citation

Adrien Girardot, Jean-Emmanuel Mignau, Edgard Renault, Magali Loupias, Aurélien Jarno, and Alban Remillieux "Metrology inside a cryostat using a cutting-edge periscope", Proc. SPIE 12618, Optical Measurement Systems for Industrial Inspection XIII, 126180J (15 August 2023); https://doi.org/10.1117/12.2673663

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