Near ultraviolet sensitivity in a modified backside illuminated CMOS sensor

Complementary metal-oxide semiconductor (CMOS) image sensors are increasingly common photometric devices used in astronomical imaging. They offer an affordable, efficient, and high-resolution method of imaging due to their characteristically low read noise, high dynamic range (HDR), and high sensor linearity compared to most modern Charge-Coupled Devices (CCD)s. However, typical hardware optimizations carry heavy emphasis on optical and near IR ranges, neglecting violet and ultraviolet wavelengths. In this proceedings, the near ultraviolet (NUV) (300-400 nm) response of a modified Sony IMX455 CMOS sensor is evaluated following the removal of its protective coated glass window. Using stable UV light sources and standard photometry techniques, we characterize the sensor’s relative quantum efficiency (QE) across the 300–400 nm range. Our results show a QE in excess of 50% at 369 nm, and in excess of 30% at 316 nm. These values support that with simple modifications, the IMX455 sensor is suitable for some applications in interstellar and galactic astrophysics, including the detection and study of exoplanets and exoplanet atmospheric features, main sequence O and B type stars, active galactic nuclei activity, interstellar dust scattering, and others. Our findings support the idea that modified CMOS sensors can serve as cost-effective alternatives to dedicated NUV detectors as data collection instruments in astronomy.