BASIC RESEARCH FOR DEVELOPMENT OF LASER SPECKLE BLOOD VELOCIMETER USING A SELF-MIXING LASER DIODE

(1)用自相关函数法测量血流：从自混合激光二极管（SM-LD）获得的散斑信号的自相关函数计算出相关时间的倒数，与偏移频率小得多的血流速度呈线性关系。(2) SM-LD散斑血流测速仪与两种市售血流测速仪的比较：SM-LD血流测速仪测量人体手指平均频率的时间依赖性与激光多普勒血流测速仪测量的血流速度的时间依赖性相似，平均时间为2秒。在测量过程中，通过调节上臂周围袖带的压力，分三个阶段改变血流量。此外，SM-LD测速仪测得的平均频率的另一个时间依赖性，平均时间为0.02秒，与血流量的时间依赖性有很好的吻合。超声多普勒血流测速仪测得的低流速，由于心脏跳动而出现重复的速度峰值。(3) SM-LD散斑血流测速仪的标定：在40 ~ 130 mm/s的流速范围内，得到的斜率参数为13 Hz/mm/s。13Hz/mm/s小于旋转转台槽内填充绵羊总血的斜率参数22Hz/mm/s。而绵羊总血流过内径为1mm和外径分别为2mm的硅管时，得到的13Hz/mm/s几乎等于15Hz/mm/s。(4)皮模和皮管模拟实验：实验中使用含有分布固定的全羊血和脂质的明胶制成的皮模板和硅静脉管，确认可测皮肤深度小于1mm，由于手指毛细血管的血流，假设测量速度。减小伪影效应是今后的研究课题之一。少

(1) Blood Flow Measurement by Autocorrelation Function Method :The inverse of the correlation time calculated from the autocorrelation function of a speckle signal obtained from a self-mixing laser diode (SM-LD) shows a linear dependence on a blood flow velocity with a far smaller offset frequency.(2) Comparison of the SM-LD Speckle Blood Flow Velocimeter with Two Commercially Available Blood Flow Velocimeters :A time dependence of the mean frequency with an averaging time 2 seconds for a human finger which was measured by the SM-LD blood flow velocimeter showed a similar tendency to a time dependence of the blood flow velocity measured by a laser Doppler velocimeter. During the measurement the blood flow was changed in 3 phases by adjusting the pressure of the cuff wound around the upper arm. Furthermore, another time dependence of the mean frequency with an averaging time 0.02 seconds obtained by the SM-LD velocimeter had fairly good coincidence with a time dependence of the blood fl … More ow velocity obtained by an ultrasonic Doppler blood flow velocimeter, which shows repeated velocity peaks due to the heart beat.(3) Calibration of the SM-LD Speckle Blood Flow Velocimeter :An obtained slope parameter was 13 Hz/mm/s in a velocity range 40 mm/s to 130 mm/s. The 13Hz/mm/s was smaller than a slope parameter 22Hz/mm/s obtained for sheep total blood filled in a gutter of a rotating turn table. While the 13Hz/mm/s was nearly equal to 15Hz/mm/s obtained for the sheep total blood flowing through a silicon tube with an inner and external diameter 1 mm and 2mm, respectively.(4) Simulating Experiment Using a Skin Phantom and a Tube :From the experiment using both a skin phantom plate made of gelatin containing distributed and fixed total sheep blood and intralipid and a silicon vein tube, a measurable skin depth was confirmed less than 1mm and the measured velocity was assumed due to the blood flow in capillaries of the finger. Reduction of the artifact effect is one of future research subject. Less