Recently, laser speckle imaging (LSI) has been applied to measuring blood perfusion in human skin. Attractive features of LSI are its temporal resolution and relatively simple instrumentation. The progressive reduction in the cost and size of camera technology now enables development of mobile LSI instrumentation. To reduce the size of LSI to a mobile platform, we are faced with new challenges in terms of reducing power consumption and heat without sacrificing detection accuracy. To address these challenges, we propose pulsed laser operation using a new automated power control (APC) circuit. By synchronizing the pulses to the laser diode driver with the camera shutter, the camera detects a similar raw speckle image as before while consuming only a small fraction of the power. Furthermore, the reduced power consumption in turn keeps the temperature of the case low, increasing the stability of the system. We validated our solution using simulations in Pspice, and we evaluated the operation of the circuit using a prototype APC board and a commercial camera.

中文翻译：

---

移动式激光散斑成像系统的自动功率控制

最近，激光散斑成像 (LSI) 已被应用于测量人体皮肤的血液灌注。LSI 的吸引人的特点是它的时间分辨率和相对简单的仪器。相机技术成本和尺寸的逐步降低现在使移动 LSI 仪器的开发成为可能。为了将 LSI 的尺寸缩小到移动平台，我们面临着在不牺牲检测精度的情况下降低功耗和热量方面的新挑战。为了应对这些挑战，我们建议使用新的自动功率控制 (APC) 电路进行脉冲激光操作。通过将脉冲与相机快门同步到激光二极管驱动器，相机检测到与以前类似的原始散斑图像，同时仅消耗一小部分功率。此外，降低的功耗反过来又使机箱的温度保持在较低水平，从而提高了系统的稳定性。我们使用 Pspice 中的模拟验证了我们的解决方案，并使用原型 APC 板和商用相机评估了电路的操作。