The optical design of the Litebird Medium and High Frequency Telescope

L. Lamagna , J.E. Gudmundsson , H. Imada , P. Hargrave , C. Franceschet , M. de Petris , J. Austermann , S. Bounissou (1) , F. Columbro , P. de Bernardis , S. Henrot-Versillé (2) , J. Hubmayr , G. Jaehnig , R. Keskitalo , B. Maffei (1) , S. Masi , T. Matsumura , L. Montier (3) , B. Mot (3) , F. Noviello , C. O'Sullivan , A. Paiella , G. Pisano , S. Realini , A. Ritacco (1, 4) , G. Savini , A. Suzuki , N. Trappe , B. Winter

1 IAS - Institut d'astrophysique spatiale
2 IJCLab - Laboratoire de Physique des 2 Infinis Irène Joliot-Curie
3 IRAP - Institut de recherche en astrophysique et planétologie
4 ENS-PSL - École normale supérieure - Paris

LiteBIRD is a JAXA strategic L-class mission devoted to the measurement of polarization of the Cosmic Microwave Background, searching for the signature of primordial gravitational waves in the B-modes pattern of the polarization. The onboard instrumentation includes a Middle and High Frequency Telescope (MHFT), based on a pair of cryogenically cooled refractive telescopes covering, respectively, the 89-224 GHz and the 166-448 GHz bands. Given the high target sensitivity and the careful systematics control needed to achieve the scientific goals of the mission, optical modeling and characterization are performed with the aim to capture most of the physical effects potentially affecting the real performance of the two refractors. We describe the main features of the MHFT, its design drivers and the major challenges in system optimization and characterization. We provide the current status of the development of the optical system and we describe the current plan of activities related to optical performance simulation and validation.

Mots clés: LiteBIRD; Cosmic Microwave Background; Polarization measurements; Millimeter wavelengths; Refractive telescopes; Space telescopes; Optical modeling; activity report; cosmic background radiation: polarization; gravitational radiation: primordial; model: optical; performance; sensitivity; detector: design; optics: design; satellite; B-mode

Domaines: Instrumentations et Détecteurs [physics.ins-det]

L. Lamagna, J.E. Gudmundsson, H. Imada, P. Hargrave, C. Franceschet, et al.. The optical design of the Litebird Medium and High Frequency Telescope. SPIE Astronomical Telescopes + Instrumentation 2020, Dec 2020, Online, United States. pp.1144370, ⟨10.1117/12.2579233⟩. ⟨hal-03107924⟩