| 摘要 |
The invention concerns a device comprising means (7) for illuminating the sample (1), designed to alternately emit first and second radiation beams; means (9) for receiving and analyzing the radiation derived from the sample (1) which include means for converting (23) the output radiation into control signal (S0); monitoring and controlling means (31) emitting first (S1) and second (S2) signals controlling the illuminating means (7), and a measuring signal (Sm); and means for calculating the absorption characteristics of the sample (1), on the basis of said measuring signal (Sm). Said monitoring and control means (31) are adapted so that, after an integration time interval (Ti) of at least one period (Tp) of variation of said radiation beams, the amplitude of said control signal (S0), sensed on the emitting phases of one of the radiation beams, is equal to the amplitude of the control signal (S0), sensed on the emission phases of the other radiation, and the measuring signal (Sm) represents at least one of said control signals (S1, S2).
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