| abstract |
An observation apparatus for endoscopes includes a light source for illumination and an endoscope which has an illumination optical system for irradiating an object with light from the light source and an image-forming optical system for obtaining an image of the object illuminated through the illumination optical system, to observe the image with fluorescent light emanating from the object. This apparatus is provided with an excitation filter device placed in an optical path to irradiate the object with the light from the light source and an observation filter device disposed in an optical path to obtain the image of the object. The excitation filter device includes a first filter having spectral transmittances such as to have a cutoff wavelength region on the short-wavelength side of wavelengths of the fluorescent light and to transmit light with shorter wavelengths than in the cutoff wavelength region. On the other hand, the observation filter device includes a fluorescence observation filter having spectral transmittances such as to have a cutoff wavelength region on the short-wavelength side of wavelengths of the fluorescent light and to transmit light with longer wavelengths than in this cutoff wavelength region. In this way, the transmissive wavelength regions of the first filter and the fluorescence observation filter are superposed at any wavelength in a wavelength region of at least 440-460 nm. |