An apparatus for optical analysis of an associated tissue sample, the apparatus comprising: - a spectrometer (110, 111) comprising an optical detector (108, 109), - a light source (104, 106), - a first light emitter arranged for emitting photons into the associated tissue sample, - a first light collector arranged for receiving photons from the associated tissue sample, - a second light emitter arranged for emitting photons into the associated tissue sample, - a second light collector arranged for receiving photons from the associated tissue sample, and where the spectrometer, the light source, the first light emitter and the first light collector are arranged for obtaining a first set of data representative of a spectrum chosen from the group comprising: a reflectance spectrum, a transmission spectrum and an absorption spectrum of the associated tissue sample, and where the spectrometer, the light source, the second light emitter and the second light collector are arranged for obtaining a second set of data representative of a fluorescence spectrum of the associated tissue sample, and the apparatus further comprising - a processor arranged for: - receiving the first set of data, and to determine a wavelength-dependent set of scattering and/or absorption coefficients from the first set of data, and to determine a distortion parameter based on the wavelength-dependent set of scattering and/or absorption coefficients, - receiving the second set of data, and - determining a third set of data representative of an intrinsic fluorescence spectrum of the associated tissue sample based on the second set of data and the distortion parameter, wherein a first distance between the first light emitter and the first light collector is substantially larger than a second distance between the second light emitter and the second light collector, and wherein a first volume of the associated tissue sample which is probed during the measuring of the first set of data substantially overlaps a second volume of the associated tissue sample which is probed during the measuring of the second set of data. - a spectrometer (110, 111) comprising an optical detector (108, 109), - a light source (104, 106), - a first light emitter arranged for emitting photons into the associated tissue sample, - a first light collector arranged for receiving photons from the associated tissue sample, - a second light emitter arranged for emitting photons into the associated tissue sample, - a second light collector arranged for receiving photons from the associated tissue sample, and where the spectrometer, the light source, the first light emitter and the first light collector are arranged for obtaining a first set of data representative of a spectrum chosen from the group comprising: a reflectance spectrum, a transmission spectrum and an absorption spectrum of the associated tissue sample, and where the spectrometer, the light source, the second light emitter and the second light collector are arranged for obtaining a second set of data representative of a fluorescence spectrum of the associated tissue sample, and the apparatus further comprising - a processor arranged for: - receiving the first set of data, and to determine a wavelength-dependent set of scattering and/or absorption coefficients from the first set of data, and to determine a distortion parameter based on the wavelength-dependent set of scattering and/or absorption coefficients, - receiving the second set of data, and - determining a third set of data representative of an intrinsic fluorescence spectrum of the associated tissue sample based on the second set of data and the distortion parameter, wherein a first distance between the first light emitter and the first light collector is substantially larger than a second distance between the second light emitter and the second light collector, and wherein a first volume of the associated tissue sample which is probed during the measuring of the first set of data substantially overlaps a second volume of the associated tissue sample which is probed during the measuring of the second set of data. - receiving the first set of data, and to determine a wavelength-dependent set of scattering and/or absorption coefficients from the first set of data, and to determine a distortion parameter based on the wavelength-dependent set of scattering and/or absorption coefficients, - receiving the second set of data, and - determining a third set of data representative of an intrinsic fluorescence spectrum of the associated tissue sample based on the second set of data and the distortion parameter, wherein a first distance between the first light emitter and the first light collector is substantially larger than a second distance between the second light emitter and the second light collector, and wherein a first volume of the associated tissue sample which is probed during the measuring of the first set of data substantially overlaps a second volume of the associated tissue sample which is probed during the measuring of the second set of data.