To provide a high-reliability spectroscopic module.
In the spectroscopic module, a collar part 7 is formed in a body along the fringe 6a of a diffraction layer 6 so as to be thicker than the diffraction layer 6, and a portion in contact with the collar part 7 of a curved surface 3a of a lens part 3 is a rough surface. Hereby, the diffraction layer 6 is enclosed by the collar part 7 having heightened adhesiveness to the curved surface 3a. Consequently, even if the diffraction layer 6 is thinned, exfoliation of the diffraction layer 6 from the convex curved surface 3a of the lens part 3 can be prevented. Furthermore, in the spectral module, a rear surface 7a facing to the curved surface 3a of the lens part 3 of the collar part 7 is a flat surface. As a result, even if a light enters the collar part 7, the light reaches the rear surface 7a which is the flat surface of the collar part 7. Consequently, the light to be imaged directly on a photodetection part of a photodetection element as stray light can be reduced.
YOSHINO TAKAFUMI
Shiro Terasaki
Satoru Ishida
Kenichi Shibayama