Spectroscopic device

A spectroscopic device comprising:

• a swing element having a swing surface and disposed such that measurement light is incident on the swing surface;
• a diffraction grating disposed at a first position on the swing surface or a second position away from the swing surface, the diffraction grating configured to disperse the measurement light traveling to be incident on the swing surface in a case where the diffraction grating is disposed at the first position, and the diffraction grating configured to disperse the measurement light reflected by the swing surface in a case where the diffraction grating is disposed at the second position;
• a first light detection unit including a first light detector configured to detect a part of the measurement light dispersed by the diffraction grating;
• a light source configured to emit inspection light to be incident on the swing surface;
• and
• a second light detection unit including a second light detector configured to detect a part of the inspection light dispersed by the diffraction grating or the inspection light reflected by the swing surface in a case where the diffraction grating is disposed at the first position and configured to detect the inspection light reflected by the swing surface in a case where the diffraction grating is disposed at the second position,
• wherein the swing element includes a support portion, a movable portion having the swing surface, and a coupling portion coupling the support portion and the movable portion such that a swing angle of the swing surface changes with a predetermined axis as a center line, and
• the second light detection unit has an elongated light receiving region in which a moving direction of the inspection light is a longitudinal direction.