Patent ID: 6169289
Filing Date: 2001-01-02
Classification: G01N,G02B

Abstract:
A multi-photon fluorescence microscope comprising: (a) a light source providing a source beam of light that includes a chosen long wavelength; (b) a microscope objective lens receiving the beam from the light source, the objective lens focussing the beam to a narrow point at which a specimen may be positioned; (c) a fluorescent light detector; (d) a first dichroic mirror positioned in an optical path between the objective lens and the fluorescent light detector, the first dichroic mirror formed to receive the multi-photon absorption fluorescent light photons that are emitted from the specimen at a wavelength shorter than the chosen long wavelength of the source beam and collected by the objective lens and to direct these photons on an optical path to the detector, the detector positioned with respect to the first dichroic mirror so that the detector receives the fluorescent light emitted from the specimen and does not detect light reflected from the specimen or light in the beam from the source; (e) a condenser lens on the opposite side of the position of a specimen from the objective lens; and (f) a second dichroic mirror positioned behind the condenser lens so that fluorescent light photons entering the condenser lens from the specimen are collected by it and directed to the second dichroic mirror which is formed to reflect wavelengths shorter than a selected wavelength, with the reflected wavelengths including the fluorescent light wavelength, and to pass light at wavelengths longer than the selected wavelength, with the passed wavelengths including the wavelength of the source beam, wherein the fluorescent light photons reflected from the second dichroic mirror are collected by the condenser and are passed back through the specimen and then through the objective lens and along the optical path of the microscope to the first dichroic mirror which directs such photons to be incident on the fluorescent light detector.