Paper 14145-303
Paper 14145-303
Split test scheme for a Gregorian space telescope: using computer generated holograms to split the test of the Gregorian telescope for Theon in the intermediate focus
9 July 2026 • 17:30 - 19:00 CEST | Room B4-M3
Abstract
We present a concept based on Computer Generated Holograms (CGH) that enables independent testing of the primary mirror (M1) and of the optical path from the Gregorian primary focus, through the secondary, to the final focus behind M1. Although the tests are carried out separately, the CGH configuration and a central reference system link both test lines, allowing highly accurate predictions of the overall Optical Telescope Assembly (OTA) performance. This decoupling of component tests greatly reduces schedule risk and cost. In addition, early use of both paths with the central reference enables rapid creation of CGH-based "as-built" telescope simulators, allowing instruments to be tested individually and early, without needing the OTA itself. The concept aligns with the "new paradigm" proposed by Arenberg, Grupp, and Kellermann [2020, 2022, 2024], which applies modular industrial building-block strategies to space optics to reduce complexity, cost, and risk.
Presenter
Univ.-Sternwarte München (Germany), Max-Planck-Institut für extraterrestrische Physik (Germany)
After working on several Échelle spectrographs like FOCES, CAFÉ, the Weihai Echelle Spectrograph and the Lamost HiRes spectrograph, Frank Grupp designed the optics and instruments of the 2m Wendelstein Telescope.
He also serves as optical architect for the ESA Euclid mission, he designed and is responsible for building and testing the near infrared wide field optics of the NISP instrument on board of Euclid. Frank joined the ESO MICADO project in 2017 designing the optics for the main selection mechanism: low resolution imager, spectrograph and pupil imager.
Working in the cosmic microwave polarization mission LiteBIRD Frank is managing the German contribution to LiteBIRD since 2019. Inside this collaboration LMU is responsible for the magnetic hood covering the detector planes of the LHFT instrument. Most recently Frank joined the Ariel consortium with a LMU contribution on the dichroic beam splitters of the common optics in Ariel.
Frank was awarded SPIE senior membership in 2021.