中文摘要：

介绍了用激光光热反射方法测量表面下物体热物性的实验原理．分析了实验中噪声的主要来源，运用带通滤光片结合差分探测的方式降低激光器产生的噪声．锁相放大技术对被测信号进行窄带放大，锁相放大器结合示波器输出了被测信号的周期变化部分，实现了光热法测量中微弱信号的测量．

英文摘要：

Introduce the principle of photo thermoreflectance technique in sub-surface imaging of ther- mal properties. Study the dominating noise. Fulfill the experiments by filtering the noise coming from the lasers by combining a bandpass filter and a differential detector, By narrowing the bandwidth of the signal and amplifying it by a lock-in amplifier, the fluctuating components of the signal can be shown on an oscillograph with lock-in amplifier.