Patent ID: 8810907

Claim:
A method of operating a surgical microscope, wherein the surgical microscope comprises: a camera having a light detecting component; microscopy optics having a first beam path for optically imaging an object region onto the light detecting component of the camera for generating image data representing intensities of images of the object region; and an illumination system configured to direct at least one illuminating light beam onto the object region; wherein the illumination light beam includes visible light from a broad wavelength range and excitation light of a fluorescence of indocyanine green of about 800 nm; wherein the illumination system comprises a first filter which is positionable at the first filter's first position in which the first filter is disposed in the illumination light beam and the first filter's second position in which the first filter is not disposed in the illumination light beam; wherein the first filter is configured to eliminate light with wavelengths greater than a predetermined wavelength from the illuminating light beam and to allow the visible light of wavelengths up to the predetermined wavelength to traverse the first filter, wherein the predetermined wavelength is in a range of one of 690 nm to 780 nm; wherein the illumination system comprises a second filter which is positionable at the second filter's fall first position in which the first filter is disposed in the illumination light beam; wherein the second filter is configured to eliminate light with wavelengths greater than 800 nm from the illuminating light beam and to allow light of wavelengths up to 800 nm to traverse the second filter; and wherein the method comprises: providing a combined fluorescence and visible light observation mode of the surgical microscope by positioning the first filter in its second position and the second filter in its first position; then recording at least one fluorescence image of the object region using the camera; and then terminating the combined fluorescence and visible light observation mode and providing a pure visible light observation mode by moving the first filter from its second position to its first position.