![Optical layout of the HRI Imager. Light from the telescope focal plane is folded by COL-M1, collimated by COL-M2 to a 40 mm pupil where the forward interchange mechanism divides the beam, and re-imaged by four surfaces in each arm. Seven reflections separate the telescope from the UVIS detector and six from the NIR detector, which is the shortest path we found that meets the requirements of Section 2, and the basis of the throughput and coating arguments of Section 3.8. -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/A-design-concept.jpg?fit=1200%2C677&ssl=1)
[astro-ph.IM] The Habitable Worlds Observatory (HWO) will be NASA’s next flagship astrophysics mission, designed to search for signs of life on planets around nearby stars and conduct transformational science across astrophysics.
Its High Resolution Imager (HRI) is not only the observatory’s main imaging camera, but also provides grism spectroscopy and sub-microarcsecond astrometry, as well as the observatory’s fine guidance, wavefront sensing and pupil imaging.
We present a design concept for HRI, developed during concurrent design sessions by flowing down science requirements within the envelope of NASA’s EAC-1 telescope architecture.
Light from a 3’x2′ field is collimated by two mirrors, then divided by a dichroic for simultaneous observations in an ultraviolet-to-visible arm covering 200-900 nm and a near-infrared arm covering 0.9-2.2 um. By minimising the number of reflective surfaces upstream of the dichroic, our optical design maximises throughput and stability, while reducing wavefront error.
Readout modes can be chosen in orbit to image the entire field in exposures of at least 10 seconds, or in smaller windows for observations up to 1 kHz. Throughout, we emphasise the interplay between subsystems that couple design choices.
The optical path as accommodated, with the UVIS arm to the right and the NIR arm to the left, showing that the layout of Figure 2 packages into the required volume without contortion. The forward interchange mechanism sits at the centre, ahead of the split, so that one mechanism reconfigures both arms. The UVIS front-end electronics are immediately behind the UVIS focal plane assembly but outside the cold enclosure, which keeps the largest dissipator in the imager out of the volume that must reach 178 K. — [astro-ph.IM]
Vincent Van Eylen, Richard Massey, Alan Smith, Jerome Amiaux, Florence Ardellier, Saeeda Awan, Patrick Curry, Daniel Dicken, Paul Eccleston, Tom Kennedy, David Linder, Chris Miller, Mat Page, Chris Pattison, Richard Robinson, Jurgen Schmoll, Dave Walton, Berend Winter
Comments: 17 pages, 14 figures, Submitted to RASTI’s HWO special issue
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2610.29957 [astro-ph.IM] (or arXiv:2610.29957v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2610.29957
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Submission history
From: Richard Massey
[v1] Wed, 21 Oct 2026 16:15:49 UTC (5,098 KB)
https://arxiv.org/abs/2610.29957
Astrobiology, Astronomy, Exoplanet,
