| 摘要 |
<p>PROBLEM TO BE SOLVED: To measure a blood flow speed with high precision by obtaining cut-off frequencies with excellent precision. SOLUTION: An FFT waveform fitting curved line by a received optical beat signal is obtained by a photo-multiplier in a step S4. In an S5, the square sum of a difference in the value of a power spectrum P with an actual RRT waveform is calculated to obtain the total To of the both. S3-S5 are repeated at prescribed intervals till the final frequency Fe and, then, fitting to the frequency is performed. Then S3-S5 are also repeated to a vascular angle to perform fitting to the vascular angle. The value of the square sum To with the vascular angleθand the frequency N1 as a variable number is finally obtained. Then the minimum value of the square sum To is obtained in an S6 and the frequencies N1 and N2 at that time are respectively adopted as the cut-off frequenciesΔfmax1,Δfmax2 in a light receiving angleβ0 in the case of receiving light by the photo-multiplier.</p> |
