Sebastian Remi, Teledyne; Kevin Kearney, Eoptic; Paul Mark, Teledyne
https://doi.org/10.64861/TUGV2729
Keywords: VisGaAs, InGaAs FPA, SWIR, Dark Current, Uniformity, photodiode Array,
Abstract:
Maintaining custody of resident space objects (RSOs) across daylight, twilight, and nighttime observation windows requires sensors that perform across a wide range of sky background conditions. Visible-band sensors are background-limited during daylight hours due to Rayleigh scattering, restricting ground-based optical SDA to twilight windows for low Earth orbit targets. Short-wave infrared (SWIR) sensing suppresses this background by approximately 20× at 1.5 µm relative to the visible, enabling custody through solar elevations exceeding 40° as recently demonstrated with ground-based InGaAs systems. However, existing SWIR sensors impose a sensitivity floor set by detector dark current and read noise that limits detection of faint or small-cross-section RSOs.
Here we present characterization of the new SCION VIS-SWIR sensor and camera, integrating a newly developed VISGaAs detector operating with 640 x 512 pixels (up to 2560 x 2048 pixels), 10 µm pixel pitch, and broadband sensitivity from approximately 300 to 1700 nm. The sensor family is suitable for both terrestrial-based imaging as well as space with camera families to support both applications. High‑dynamic‑range, low noise and high‑frame‑rate imaging are supported, providing multiple observing modes depending on the information target. These capabilities combined with deep cooling and advanced readout modes like sample up the ramp address sensitivity limitations commonly encountered in in detection of weak broadband signals. Full frame rates of more than 700fps allow for sensitive capture of moving objects and transient signals. The single focal-plane broadband architecture eliminates the co-boresighting requirement of dual-sensor VIS+SWIR designs, with direct implications for system alignment stability and SWaP in fielded SDA instruments.
We evaluate SCION VIS-SWIR performance against three SDA collection modes: daytime and twilight RSO custody, broadband spectral discrimination for material classification, and faint RSO detection against dark sky backgrounds. The daytime custody case is examined in depth through end-to-end radiometric modeling parameterized on the measured detector characterization data, establishing detection thresholds as a function of solar elevation, target cross-section, and phase angle for ground-based deployment. Results are compared against the published performance of current InGaAs SDA systems, quantifying the sensitivity improvement attributable to the SCION detector noise floor.
Date of Conference: September 15-18, 2026
Track: SDA Systems & Instrumentation