Patent ID: 7368694

Claim:
Device for measuring light absorption characteristics of a biological tissue sample comprising: means for illumination ( 7 ; 307 ) of the sample ( 1 ) adapted to emit alternately at least one first and one second light radiation beam towards the sample, said radiation beams having respectively a first and a second wavelength which are different from one another; means ( 9 ) for reception and analysis of the output light radiation emitted by the sample ( 1 ), said reception and analysis means ( 9 ) comprising means ( 23 ) for converting said output radiation into a monitoring signal (S 0 ); monitoring and control means ( 31 ; 331 ) which receive the monitoring signal (S 0 ) as input and emit at the output at least first (S 1 ) and second (S 2 ) control signals for controlling the illuminating means ( 7 ; 307 ), corresponding to the first and second radiation beams respectively, and at least one measurement signal (S m ); and means ( 33 ) for computing the absorption characteristics of the sample ( 1 ) which are adapted to receive said measurement signal (S m ) as input and to compute said characteristics as a function of said measurement signal (S m ), characterised in that said monitoring and control means ( 31 ; 331 ) are adapted so that the light intensity (I UV , I R ) of each of the radiation beams varies in a periodic manner, phase-shifted with respect to one another, and so as to regulate at least one of the control signals (S1, S 2 ) as a function of the monitoring signal (S 0 ) in such a way that, over an integration time period (T i ) of at least one period (T p ) of variation of said radiation beams, the amplitude of said monitoring signal (S 0 ) taken over the emission phases of one of the radiation beams is equal to the amplitude of the monitoring signal (S 0 ) taken over the emission phases of the other radiation beam, and in that the measurement signal (S m ) represents at least one of said control signals (S 1 , S 2 ) over the integration time period (T i ).