The Herschel-PACS grating mechanism: mechanical and optical performance

B. Marquet; J. Y. Plesseria; E. Renotte; P. Royer; R. Vavrek

doi:10.1117/12.789281

23 July 2008 The Herschel-PACS grating mechanism: mechanical and optical performance

B. Marquet, J. Y. Plesseria, E. Renotte, P. Royer, R. Vavrek

Proceedings Volume 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation; 701825 (2008) https://doi.org/10.1117/12.789281
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

The Photodetector Array Camera and Spectrometer (PACS), on board the Herschel Space Observatory, is designed for imaging and low and medium resolution spectroscopy in the wavelength region between 57 and 210 μm. This paper reports the design and the testing results of the grating cryogenic mechanism of the PACS spectrometer. The PACS diffraction grating is made from an aluminium substrate, mechanically ruled with a periodicity of 8.5 grooves per mm and gold coated for optimum reflectivity at PACS operating wavelengths. The grating mechanism is capable of accurate positioning (4") of the flat diffraction grating within a large angular throw (44°) in cryogenic environment (4.2 K). Technologies of actuators, position sensors, bearings, servo-control and cryogenic test set-up are presented. The grating mechanism was thoroughly tested, alone and when integrated in the PACS Focal Plane Unit (FPU). The tests were performed in cryogenic conditions, in a set-up fully representative of the flight conditions. Actual mechanical and optical performance obtained with the Flight Model (FM) is presented in detail. Quality of the angular positioning of the mechanism, spectral resolution and optical quality of the grating are analysed.

Citation Download Citation

B. Marquet, J. Y. Plesseria, E. Renotte, P. Royer, and R. Vavrek "The Herschel-PACS grating mechanism: mechanical and optical performance", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 701825 (23 July 2008); https://doi.org/10.1117/12.789281

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available