A method to measure glucose within the blood of a tissue test area includes illuminating the tissue test area using a single mode light source at a point of incidence, with at least some of the light penetrating tissue at the point of incidence calibrating the light source by adjusting a distance between the point of incidence and an axicon lens collecting returning radiation from the tissue test area at a point offset from the point of incidence removing tissue fluorescence using edge filters removing additional tissue fluorescence by shifting the excitation wavelength of the single mode light source heating the test area and analyzing a returned Raman signal to determine the glucose within the blood.
