Patent ID: 6028622
Filing Date: 2000-02-22
Classification: A61B

Abstract:
An observation apparatus for endoscopes, comprising:an illumination light source;an endoscope having an illumination optical system constructed and arranged to irradiate an object to be observed with light from said illumination light source and an image-forming optical system constructed and arranged to obtain an image of the object illuminated through said illumination optical system and to observe the image with fluorescent light emanating from the object;an excitation filter system placed in an optical path of illumination light from said illumination light source; andan observation filter system disposed in an optical path of light that is formed into the image of the object,said excitation filter system including:a first filter having a spectral transmittances including a cutoff wavelength region on a short-wavelength side of wavelengths of the fluorescent light and a transmitting wavelength region at shorter wavelengths than in the cutoff wavelength region of said first filter, anda second filter with a cutoff wavelength region that is shifted from the cutoff wavelength region of said first filter toward a short-wavelength side,said first filter and said second filter being constructed and arranged to be selectively insertable in and out of the optical path of illumination light,said observation filter system including a fluorescence observation filter having a spectral transmittance including a cutoff wavelength region on a short-wavelength side of wavelengths of the fluorescent light and a transmitting wavelength region at longer wavelengths than in the cutoff wavelength region of said fluorescence observation filter,wherein transmissive wavelength regions of said first filter and said fluorescence observation filter are superposed at least at a wavelength in a wavelength region of 440-460 nm.