Arrangement and method for the measurement of stock parameters in the form of layers of media, in particular for the calibration free in vivo measurement of the oxygen saturation in optically accessible blood vessels

摘要

The substance parameter measurement involves examining the area to be measured (20) using an ocular (7), showing one layer (27) of a vein and its vicinity (24). A confocal aperture (38) sends lights beams with varying wavelengths onto the area. Measurements of the reflection and scattering of light are taken and store in a polychromator (15). The intensity of the signals are verified and corrected if necessary by analysing two neighbouring but different areas (O1,O2). The spectral and local measurements are calculated using the following formulae : I(O, lambda )=Im(O, lambda )-K( lambda ), where I(O, lambda ) is the intensity of the corrected spectral and local signal, Im(O, lambda ) is the intensity of the spectral an local signal, and K( lambda ) is the spectral scattering light constant. The extinction spectrum of the structure (25) is given by E(O, lambda ) where E(O, lambda )=logI(O1, lambda )/logI(O2, lambda ). This is followed by a non-linear compensation calculation.