Fleming B P, Klitzman B, Johnson W O
Am J Physiol. 1985 Oct;249(4 Pt 2):H899-905. doi: 10.1152/ajpheart.1985.249.4.H899.
An optical velocimeter employing a linear array of photodiodes has been developed and utilized for measuring erythrocyte velocities in the microcirculation. A magnified image of a microvessel is projected and aligned on a one-dimensional array of photodiodes. Photocurrent from odd-ordered diodes is summed, photocurrent from even-ordered diodes is summed, and a signal proportional to the difference between these two currents is produced by a differential amplifier. The center frequency of the output signal of the differential amplifier is proportional to the erythrocyte velocity. After lowpass filtering the output of the differential amplifier, a signal proportional to its frequency and therefore velocity is produced by a frequency-voltage converter. In vitro calibration with a moving dried smear of erythrocytes illustrated a linear relation between the output of the frequency-voltage converter and erythrocyte velocity for a wide range of velocities and magnifications. The system produces a stable zero output at zero velocity and had an estimated frequency response of greater than 40 Hz in vivo. Volumetric flow rates computed from velocity and diameter measurements at arteriolar bifurcations in the rat cremaster muscle were consistent with mass conservation.
一种采用光电二极管线性阵列的光学测速仪已被开发出来，并用于测量微循环中的红细胞速度。微血管的放大图像被投射并对准在一维光电二极管阵列上。奇数序号二极管的光电流被求和，偶数序号二极管的光电流被求和，并且差分放大器产生一个与这两个电流之差成比例的信号。差分放大器输出信号的中心频率与红细胞速度成比例。在对差分放大器的输出进行低通滤波之后，频率 - 电压转换器产生一个与其频率（因此与速度）成比例的信号。用移动的红细胞干涂片进行的体外校准表明，在很宽的速度和放大倍数范围内，频率 - 电压转换器的输出与红细胞速度之间呈线性关系。该系统在零速度时产生稳定的零输出，并且在体内估计的频率响应大于40Hz。根据大鼠提睾肌小动脉分支处的速度和直径测量值计算出的体积流量与质量守恒一致。
