Patent ID: 8471218

Claim:
A detecting device for fluorescence observation, the detecting device comprising: a wavelength dispersion element for dispersing light into wavelengths, and for emitting dispersed light, the dispersed light including component light having an excitation wavelength and component light having a fluorescence wavelength; a photodetector for detecting the dispersed light, the photodetector being arranged in a wavelength dispersion direction of the dispersed light; and a wavelength restriction element, which is arranged between the wavelength dispersion element and the photodetector and has an optical characteristic dependent on a wavelength, for restricting an incidence to the photodetector of the component light having the excitation wavelength which is included in the dispersed light, the optical characteristic of the wavelength restriction element being such that, when the dispersed light emitted by the wavelength dispersing element is incident to the wavelength restriction element, the component light having the excitation wavelength is restricted, and the component light having the fluorescence wavelength is transmitted through the wavelength restriction element, wherein the wavelength restriction element is arranged in a spatial region to which the component light having the excitation wavelength is incident, and the wavelength restriction element has a width in the wavelength dispersion direction greater than a width in the wavelength dispersion direction of the component light having the excitation wavelength in a plane corresponding to an incidence plane of the wavelength restriction element, and smaller than a total width in the wavelength dispersion direction of the dispersed light in said plane.