Patent ID: 7623243

Claim:
A spectroscopic device for spectroscopically separating detected light into light beams having different wavelength ranges and optically receiving light of each wavelength range by a light-receiving face of a photodetector comprising: a dichroic mirror array having a plurality of dichroic mirrors, each of the dichroic mirrors having a long wavelength range side that comprises a light transmissible range of wavelengths and the shortest wavelengths of the light transmissible ranges of the respective dichroic mirrors are different from each other, and that are arranged along an oblique direction of a plane opposing a light-receiving face at a predetermined inclination angle to the light-receiving face in a decreasing order of the shortest wavelength so as to be substantially parallel to the plane; and a reflection member that is disposed at the light reflection side of the dichroic mirror array and equipped with a reflection face opposing the dichroic mirrors substantially parallel to the dichroic mirrors, wherein the plane is inclined so that the dichroic mirror side having the minimum shortest wavelength is nearer to the light-receiving face than the dichroic mirror side having the maximum shortest wavelength, the detected light is made incident to the dichroic mirror having the maximum shortest wavelength along the perpendicular direction of the light-receiving face.