Multispectral Filter with No Need in Alignment

OSA publishes a paper "Alignment-free filter array: Snapshot multispectral polarization imaging based on a Voronoi-like random photonic crystal filter" by Kazuma Shinoda and Yasuo Ohtera from Utsunomiya University and Toyama Prefectural University, Japan.

"We develop a photonic crystal filter with a new structure and propose a method to realize a snapshot multispectral polarization camera by mounting the filter on a monochrome imager with no requirement for a specific alignment. The developed filter is based on the Voronoi structure, which forms multilayered photonic crystals with random wave-like structures in each of the Voronoi cells. Because the transmission characteristics of the multilayered photonic crystal can be controlled simply by changing the microstructure, there is no need to change the manufacturing process and materials for each Voronoi cell. Furthermore, the Voronoi cell is randomly distributed so that the filter can be junctioned with the imager at arbitrary positions and angles without the need to position the filter during mounting, although it requires measurement of the camera characteristics and an image restoration process after filter mounting. In this experiment, we evaluated to reconstruct spectra as well as linearly polarized components and RGB images in the visible wavelength range from a single exposure image."