A method and device are presented for use in non-invasive optical measurements
of at least one desired characteristic of patient's blood. A condition of artificial
blood kinetics is created at a measurement location in a patient's blood perfused
fleshy medium and maintained for a certain time period. This condition is altered
over a predetermined time interval within said certain time period so as to modulate
scattering properties of blood. Optical measurements are applied to the measurement
location by illuminating it with incident light beams of at least two different
wavelengths in a range where the scattering properties of blood are sensitive to
light radiation, detecting light responses of the medium, and generating measured
data indicative of time evolutions of the light responses of the medium for said
at least two different wavelengths, respectively, over at least a part of said
predetermined time interval.