本文用小型半导体激光器做单色弱光源，用光电效应法测量普朗克常量，具有精度高、体积小、重量轻、成本低、节约电、使用方便等优点.用光谱分析论证了与相关其他光源比较，半导体激光器光源具有较好的单色性，理论分析了单色光谱线宽度影响测量精确度的原因.

An experimental method of small semiconductor laser weak light source for measuring the Planck constant based on the photoelectric effect is adopted. It has the advantages of high precision， small volume， light weight， low cost， save electricity，convenient. It has been demonstrated that the semiconductor laser light source has a good monochromaticity compared with the related other light source by the spectral analysis. The reasons of influencing the measurement accuracy because of the monochromatic spectral line width are analyzed theoretically.