Time-resolved characterization of stray light

Traditional approach to stray light characterization is intrinsically limited. While the stray light level in an optical instrument can be measured, it is not possible to derive from experimental measurements the origin of the different features. Consequently, when unexpectedly high stray light is present, it is extremely difficult to find how to improve the system. In this paper, we introduce a new method where a pulsed laser and an ultra-fast sensor is used. As different stray light contributors have different optical path lengths, they reach the detector at different times and resolving them temporally allows to measure them separately. Their origin can be retrieved by using the optical path length as a mean of identification. We present the conceptual study and the experimental proof of concept of this new method. We were able to characterize individually the different stray light components in an imaging system and determine their origin. We show how the measurements allow to reverse engineer the instrument properties and even verify sub-system requirements.