Patent ID: 7406347

Claim:
A device for making visible a pathological change in a part of a patient's body labeled with a fluorescent dye, comprising: a first switchable light source configured to emit light having a wavelength essentially matching an excitation wavelength of the fluorescent dye for triggering the emission of light having a wavelength essentially matching an emission wavelength of the fluorescent dye and for producing a first image; a second switchable light source configured to emit visible light having a wavelength different from the emission wavelength of the fluorescent dye for producing a second image; a switching device configured to create an impression of a merged image of the first and second images by alternately switching on and off the first and second switchable light sources at a frequency such that a human eye cannot differentiate between the first and second images; and a filter for filtering out components of ambient light having a wavelength essentially matching the emission wavelength, wherein the filter is configured to be switched on and off in sync with the second light source.