An updated camera system for real-time Optical Calibration in TRIDENT

The performance of a neutrino telescope is fundamentally dependent on the optical properties of its detection medium. For deep-sea neutrino telescopes like the TRopIcal DEep-sea Neutrino Telescope (TRIDENT), a real-time, in-situ optical calibration system is essential due to the dynamic nature of the deep-sea environment. In 2021, a camera-based optical calibration system was initially demonstrated in the TRIDENT Pathfinder experiment (TRIDENT Explorer, T-REX 2021). Following up on this first pathfinder mission, an upgraded camera system was deployed in 2024 further to validate its effectiveness and long-term stability under deep-sea conditions. The updated camera system features two types of CMOS cameras, one for simultaneous optical calibration and the other dedicated to bioluminescence monitoring. Additionally, the range of calibration wavelengths has been expanded compared to the T-REX 2021 configuration, improving the spectral resolution in optical measurements. In this work, we present the design, instrumentation, and performance of the updated system after weeks of continuous undersea operation.