光源的相干性对牛顿环干涉条纹的影响

Impact of coherency of optical sources on interference fringes of Newton rings

利用波前理论中的相因子分析法分别对牛顿环装置在相干光和非相干光照射下的干涉条纹进行分析.理论分析表明,在相干光照射下,主要有2套干涉条纹,且条纹半径随空间位置变化而变化,当在平凸透镜顶点附近观察时,条纹半径公式与教材中一致;在非相干光照射下,只有空气层上下表面反射的光形成干涉条纹,条纹定域在平凸透镜曲面之上的附近区域,条纹半径公式近似与教材一致.

The interference fringes of Newton ring illuminated by coherent and incoherent light, respectively, are analyzed with phase factor. The theoretical analysis shows that two sets of interference fringes with location dependent radius are observed when illuminated by coherent light. The formula of the fringe radius was in accordance with that in textbooks where observation is conducted near the vertex of plate-convex lens. But when the Newton ring is illuminated by incoherent light, only one set of interference fringes, caused by the reflection of light between top and bottom surface of the air layer and the radius formula is approximately in accordance with that in textbooks.