Biophotonic device for the point-of-care, real-time, non-invasive determination of parameters with diagnostic relevance, in particular an optical system for parameter characterization of an element of body fluid or tissue comprising an optical device which comprises: a light source for emitting light onto the element; and a spectrometer for recording the spectrum of light from the element, said light from the element being of transmittance, reflectance or Raman scattering of the emitted light by said element; the optical system further comprising a data processing module configured to: convert the recorded spectrum by a conversion matrix into a standardized spectrum, wherein said conversion matrix has been obtained by calibrating the optical system spectrum response against a spectrum reference; pre-process the converted spectrum; correlate, for parameter quantification, the converted pre-processed spectrum with pre-obtained spectral bands for each parameter; said spectrum being contained within uv-vis-nir wavelengths. Also methods of operating said system.