报道了激光散斑时间漂移效应.引入了散斑模型，接收面上散斑场复振幅的强度和位相的统计性质证明了模型的合理性.基于此模型和相关算法，模拟了所有可能导致激光散斑时间漂移效应的物理因素的影响.模拟结果显示两个因素起主要作用.通过巧妙地改变VCSEL和CCD的工作状态，也证明了两个因素其主要作用,即激光器对表面的加热引起的表面膨胀和CCD的热效应带来的噪声增加.相比之下，其他因素仅仅会带来散斑图像的微小变化.

The time-drift effect of laser speckle was reported. A speckle model was introduced. The validity was verified by the statistical properties of intensity and argument of the complex amplitude at the observation plane. Based on this speckle model and correlation method between speckle patterns, nearly all physical factors which may result in the time-drift effect of speckle according to experimental parameters were simulated.The results show that two factors,which vertical-cavity surface-emitting laser(VCSEL) and charge coupled device(CCD),Other factors such as fluctuation of laser intensity, changes of wavelength of light and air refractive index, etc., only bring tiny changes of speckle pattern, or even do not cause the time-drift effect of laser speckle at all.