关键词: 坡印亭矢量, 电磁辐射压强, 激光笔

Abstract: When giving presentations, many people use a laser pointer to direct the attention of the audience to information on a screen. The primary properties of laser light that make it useful in these technological applications are these ： high intensity and a small angle of divergence. In this paper, using laser light radiate pressure, the pres- sure from laser pointer is derived and analyzed. The result shows that even for the radiated pressure from a 3.0-mW laser pointer is about the same as that of sunlight at the Earth＇ s surface. For this reason, it is not safe to shine the beam of a laser pointer into a person＇ s eyes, which may be more dangerous than looking directly at the Sun.

Key words: Poynting vector, electromagnetic radiation pressure, laser pointer