公开(公告)号：US10564334B2

公开(公告)日：2020-02-18

申请号：US15559908

申请日：2016-03-28

Applicant: Konica Minolta, Inc.

Inventor： Hidetaka Jidai ,  Munenori Kawaji ,  Ryoji Matsuda

IPC: G02B27/00 ,  G02B5/28 ,  G01J3/36 ,  G01J3/26 ,  G01J3/28

Abstract: A spectral filter (10) is provided with a long-pass filter (12) and a short-pass filter (13). The long-pass filter (12) has a film thickness gradient GL wherein film thickness increases monotonically in a single direction, and transmits light of a wavelength region longer than a cut-off wavelength WL. The short-pass filter (13) has a film thickness gradient GS wherein film thickness increases monotonically in a single direction, and transmits light of a wavelength region shorter than a cut-off wavelength WS. The long-pass filter (12) and the short-pass filter (13) are overlapped such that the single directions match each other. At the positions in the single directions, a transmittance peak is formed by the cut-off wavelength WL being shorter than the cut-off wavelength WS. The film thickness gradient GL is greater than the film thickness gradient GS.