Identify the additional optical-loss sources in the TIM long-wavelength system

Identify the additional optical-loss sources between the TIM long-wavelength LEKID detectors and the blackbody radiator that account for the measured optical efficiency of approximately 0.67, including whether losses in the waveguide are responsible.

Background

The paper measures a median optical efficiency of approximately 0.67 for the Terahertz Intensity Mapper long-wavelength LEKID array. This is lower than the approximately 90% band-averaged absorption efficiency expected for the chain-link absorber, indicating that additional losses occur somewhere between the detector and the blackbody radiator.

The location and physical origin of these losses are not established. The authors tentatively attribute them to waveguide losses, but identifying the missing loss sources is necessary for fully characterizing the optical efficiency of the flight system.