[21a-E208-1~12] 【CS.4】 Code-sharing Session of 3.11 & 3.12

[21a-E208-2] Absorptive angular-selective filters using multilayers

〇Yasuhiko Takeda¹, Taichi Maruya², Hideyuki Tanaka³ (1.Toyota Central R&D Labs, 2.Denso Wave, 3.DENSO CORP.)

Keywords:bandpass filter, interference, dielectric multilayer

We have proposed a concept of an angular-selective filters (ASFs) that transmits the incident light in the transmitting range and mostly absorb in the blocking range. The absorptive ASF consists of a transparent dielectric multilayer combined with a thin absorbing layer. We have clarified the design guide to select the suitable multilayer structure and absorbing material. Concrete structures of three types were designed using Cr for the absorbing material on the basis of SiO₂/TiO₂ bandpass, shortpass, and longpass filters, exhibiting the absorptive ASF functions for the transmitting/blocking ranges of 0-10°/10-30°, 0-30°/30-60°, and 10-60°/0-10°, respectively. The absorptive ASF solves the issue that the light in the blocking range reflected by a conventional ASF of transparent dielectric materials partially becomes spray light and thus lowers the signal-to-noise ratio. The present multilayered structures have a great advantage for practical use; no need of microfabrication processes.