Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Experimental tests of the calibration of high precision differential astrometry for HWO

Manon Lizzana, Fabien Malbet, Alain Leger, Fabrice Pancher, Sébastien Soler, Hugo Rousset, Thierry Lepine, Julien Michelot, Yahya Er-Rahmaouy, Youssef Bakka

TL;DR

The paper addresses the challenge of achieving sub-$0.3 μas$ differential astrometry for Habitable Worlds Observatory (HWO) and presents a program of detector characterization, pixel-centroid interferometric calibration, and optical-distortion calibration. It characterizes the Gigapyx 46Mpx CMOS detector, develops an interferometric testbed to measure pixel centroids at sub-pixel scales, and validates a 2D polynomial distortion model through Zemax simulations and laboratory tests. It reports sub-$5×10^{-6}$ px precision in ideal simulations and $0.04$ px lab accuracy, outlining a practical calibration workflow and demonstrating feasibility for a multi-detector focal plane to cover the WFI FOV. The work provides concrete metrology and detector requirements that inform HWO's high-precision astrometry program and exoplanet/dark-matter science cases.

Abstract

Many different scientific applications require sub-micro arcsecond precision astrometry, including researching rocky exoplanets in the vicinity of the Sun and studying dark matter. The Habitable Worlds Observatory (HWO) is a promising candidate to carry an astrometric instrument because it provides a stable, space-based telescope with a large aperture, which allows faint sources and small displacements to be observed. This paper presents the characterization of an appropriate detector for an astrometric instrument: the 46Mpx Gigapyx from Pyxalis. Moreover it explains the implementation of a testbed enabling interferometric characterization of pixel positions. Finally, the paper introduces a method for calibrating the telescope's optical distortion. This method was implemented in simulation and tested thanks to an optical bench developed at IPAG in France.

Experimental tests of the calibration of high precision differential astrometry for HWO

TL;DR

The paper addresses the challenge of achieving sub- differential astrometry for Habitable Worlds Observatory (HWO) and presents a program of detector characterization, pixel-centroid interferometric calibration, and optical-distortion calibration. It characterizes the Gigapyx 46Mpx CMOS detector, develops an interferometric testbed to measure pixel centroids at sub-pixel scales, and validates a 2D polynomial distortion model through Zemax simulations and laboratory tests. It reports sub- px precision in ideal simulations and px lab accuracy, outlining a practical calibration workflow and demonstrating feasibility for a multi-detector focal plane to cover the WFI FOV. The work provides concrete metrology and detector requirements that inform HWO's high-precision astrometry program and exoplanet/dark-matter science cases.

Abstract

Many different scientific applications require sub-micro arcsecond precision astrometry, including researching rocky exoplanets in the vicinity of the Sun and studying dark matter. The Habitable Worlds Observatory (HWO) is a promising candidate to carry an astrometric instrument because it provides a stable, space-based telescope with a large aperture, which allows faint sources and small displacements to be observed. This paper presents the characterization of an appropriate detector for an astrometric instrument: the 46Mpx Gigapyx from Pyxalis. Moreover it explains the implementation of a testbed enabling interferometric characterization of pixel positions. Finally, the paper introduces a method for calibrating the telescope's optical distortion. This method was implemented in simulation and tested thanks to an optical bench developed at IPAG in France.
Paper Structure (7 sections, 6 figures, 1 table)

This paper contains 7 sections, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. Proposed focal plane concept
  3. Interferometric calibration of the pixel centroid position
  4. Calibration of optical distortion
  5. Numerical simulations
  6. Laboratory results
  7. Conclusion

Figures (6)

  • Figure 2: Characterization of the Gigapyx 46Mpx detector from Pyxalis. Top left : photon transfer curve; top right : response curve; bottom left : signal to noise histogram; top right : bad pixel map
  • Figure 3: Example of focal plane assembly with four 220M detectors and one 14M
  • Figure 4: Interferometric fringes from the IPAG testbed pictured by the 46Mpx, top: zoom on images from the 46M gigapyx; bottom: spatial cuts. The wavelength is $632$ nm and the fibers are separated by 1 mm.
  • Figure 5: Scheme of the interferometric calibration testbed at IPAG, France pancher2024laboratorycharacterisationbenchhigh
  • Figure 6: Photo of the distortion calibration testbed at IPAG, France (see pancher2024laboratorycharacterisationbenchhigh for more details)
  • ...and 1 more figures