Optical design adopting tilted filters for reduction of stray light in planetary exploration cameras and other optics

Multiband optical cameras have played important roles in science observations for many planetary explorations. To ensure high-quality imaging observations using a camera, it is crucial to reduce stray light, which is defined as light reaching an imaging detector via an irregular path in this study. Multiple reflections between a detector and a bandpass filter are often the major sources of stray light in planetary camera optics. In this article, we present a study for camera optics using tilted bandpass filters to reduce stray light caused by multiple reflections between a detector and bandpass filters. A comparative study for four cases of optical design, which have different configurations of the bandpass filter, was conducted. A case of optical design adopting a combination of X- and Y-tilted filters provided high performance. The results of this study are potentially applicable not only for cameras for planetary exploration but also for various other optics.