Comparing the contrast performance of two IFU technologies for exoplanet direct imaging with ELT-PCS

Conference item

A key science goal for the Planetary Camera and Spectrograph (ELT-PCS) instrument is to image rocky exoplanets in reflected light around nearby M- and K-dwarfs. These observations will require a contrast of 10−9 at 100 mas angular separation, and 10−8 at 10 mas. To achieve such an extreme performance, every instrument design choice must be carefully evaluated. For ELT-PCS’s science instruments, perhaps the most critical design choice is which integral field unit (IFU) technology to use. To this end, we have developed a modular, lab-based integral field spectrograph test bench with which to compare the performance of two popular IFU technologies: image slicers and lenslet arrays. The test bench implements a Lyot coronagraph and a spatial light modulator to simulate a high-contrast imaging system, which feeds each IFU with a diffraction-limited PSF image. Each IFU is coupled to the spectrograph, which achieves R≈3000 with the image slicer and R≈100 with the lenslet array. The calibration and data reduction for each IFU design are described and the initial results of a contrast comparison are presented. The lenslet array achieves a deeper contrast at angular separations of less than 6λ/D. The image slicer, however, gains more at small separations from applying spectral deconvolution, with a 3.4× greater gain at 4λ/D. Spectral deconvolution further yields a contrast curve close to the detector noise floor. Further work will focus on carrying out a fully-controlled characterisation of the lenslet array IFU and a more comprehensive study into the effects of adaptive optics residuals on the contrast.

Authors: Griffiths, R; Maharana, S; Tecza, M

• Publication status: Published
• Peer review status: Reviewed (other)
• Publisher: SPIE
• Host title: Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation VII
• Journal: Proceedings of SPIE More from this journal
• Volume: 14154
• Article number: 1415417
• Publication date: 2026-08-21
• Event title: SPIE Astronomical Telescopes + Instrumentation, 2026
• Event location: Copenhagen, Denmark
• Event start date: 2026-07-05
• Event end date: 2026-07-11
• DOI: 10.1117/12.3104913
• EISSN: 1996-756X
• ISSN: 0277-786X
• EISBN: 9798902323501
• ISBN: 9798902323495
• Language: English
• Keywords: high-contrast imaging; exoplanets; direct imaging; integral field spectroscopy