Optischer Korrelator und Verfahren zur Korrelation optischer Signale

摘要

The blood mean speed of flow in surface-near tissue layers may be measured by analysing the speckle pattern of intensity fluctuation caused by red blood cells. For that purpose, optical correlators are needed that can simultaneously sense and evaluate in parallel several thousands of individual speckles. The disclosed correlator has optics (3, 4) that reproduce the speckle pattern to be analysed on a light modulator/detector unit (6, 9) and on a detector having radiation-sensitive areas Sij. A computer (8) that receives the output signals from the detector (5) delayed each by time interval tau controls the light modulator (6) so that the transmission of a modulator area Mij at time t depends on the intensity Iij measured in the associated detector area Sij (t* = t - tau ). The detector (9) connected downstream of the light modulator (6) then generates an output signal that is proportional to the autocorrelation function of the speckle reproduced on Mij. The invention has applications in laser Doppler measurement equipment and blood irrigation measurement equipment.