Precision Projector Laboratory: Detector Characterization with an Astronomical Emulation Testbed

TL;DR

This paper introduces a laboratory emulation testbed for detector characterization in astronomical sensors, enabling realistic validation of detector performance and aiding mission design without relying solely on physical understanding.

Contribution

The paper presents a novel emulation testbed that simulates astronomical scenes for detector testing, bridging the gap between physical modeling and real-world validation.

Findings

Supports emulation of various mission scenarios like WFIRST and JWST

Provides highly predictable, stable, and realistic image patterns

Enables validation of detector performance with science-like images

Abstract

As astronomical observations from space benefit from improved sensitivity, the effectiveness of scientific programs is becoming limited by systematics that often originate in poorly understood image sensor behavior. Traditional, bottom-up detector characterization methods provide one way to model underlying detector physics, and generate ever more faithful numerical simulations, but this approach is vulnerable to preconceptions and over-simplification. The alternative top-down approach is laboratory emulation, which enables observation, calibration, and analysis scenarios to be tested without relying on a complete understanding of the underlying physics. This complements detector characterization and simulation efforts by testing their validity. We describe a laboratory facility and experimental testbed that supports the emulation of a wide range of mission concepts such as gravitational weak lensing measurements by WFIRST and high precision spectrophotometry of transiting exoplanets by JWST. An Offner relay projects readily customizable "scenes" (e.g. stars, galaxies, spectra) with very low optical aberration over the full area of a typical optical or near infrared image sensor. f/8 and slower focal ratios may be selected, spanning those of most proposed space missions and approximating the point spread function (PSF) size of seeing limited ground based surveys. Diffraction limited PSFs are projected over a wide field of view and wavelength range to deliver highly predictable image patterns down to sub-pixel scales with stable intensity and fine motion control. The testbed enables realistic validation of detector performance on science-like images, which aids mission design and survey strategy, as well as targeted investigations of various detector effects.