An interference of two beams coming from one laser is a well-known and popular experiment. But is it possible to obtain interference fringes using two completely independent laser sources? If the answer is ‘yes’, is such an observation available in a typical optical laboratory? We show a simple but spectacular method of observing such an interference, using very common continuous wave He–Ne lasers as well as diode lasers often found in atomic physics laboratories. The contrast of the fringes ranges from 27% to 87%, depending on the laser properties. The method works for both single and multi-mode unstabilized He–Ne lasers. The fringes are visible on a scientific as well as on a common security camera.

来自一个激光器的两束光束的干涉是一项众所周知且流行的实验。但是是否有可能使用两个完全独立的激光源获得干涉条纹？如果答案是“是”，那么在典型的光学实验室中是否可以进行这样的观察？我们展示了一种观察这种干涉的简单而壮观的方法，使用非常常见的连续波 He-Ne 激光器以及原子物理实验室中常见的二极管激光器。条纹的对比度范围从 27% 到 87%，具体取决于激光特性。该方法适用于单模和多模不稳定 He-Ne 激光器。边缘在科学和普通安全摄像头上都是可见的。