| abstract |
A filter set for observing fluorescence radiation in biological tissue with at least one illumination filter (L; L ') and at least one observation filter (O1, O1', O2, O2 ') is proposed. The at least one illumination filter (L; L ') can be arranged in an illumination system of an optical system and has a first wavelength passband (D1) and a first wavelength stopband (S1) for longer wavelengths (λ) than in the first wavelength passband ( D1). The at least one observation filter (O1, O1 ', O2, O2') is locatable in an imaging system of the optical system and has a second wavelength passband (D2) for longer wavelengths (λ) than in the first wavelength passband (D1) of the at least one an illumination filter (L; L ') and a second wavelength blocking region (S2, S2') for shorter wavelengths (λ) than in the second wavelength transmission region (D2). In this case, a transmittance (T L (λ), T L ' (λ), T O1 (λ), T O2 (λ)) for wavelengths (λ) in the first and second wavelength passband (D1, D2) is greater than 0.5 and in the first and second wavelength-blocking range (S1, S2, S2 ') each less than 0.5. Further, a product of the transmittance (T L (λ), T L ' (λ)) for wavelengths (λ) of the at least one illumination filter (L; L') and the transmittance (T O1 (λ), T O2 (λ) ) for wavelengths (λ) of the at least one observation filter (O1, O1 ', O2, O2') ... |