用迈克尔逊干涉仪测量全息干板膜厚度

全息干板膜的厚度是全息干板的重要参数之一。使用迈克尔逊干涉仪和白光光源对2种全息干板膜厚度进行测量，并对测量结果误差进行分析，给出了测量误差与膜厚及折射率之间的关系以及此方法的适用范围。研究结果表明：在膜厚从8μm增至41μm的过程中，测量结果的绝对误差≤2μm且变化很小，相对误差则从14.1%降到了2.2%。随着膜厚的增加，相对误差明显降低；折射率n也参与了误差传递，其值与测量误差呈类似反比关系；当n值在1.5附近时，为保证测量的准确性，所测膜厚≥40μm。最后指出，迈克尔逊干涉仪在测量全息干板膜等较厚的薄膜时，具有测量范围大，结果较准确等优点。

Thickness measurement of thin film for holographic plate by Michelson interferometer

Thin-film thickness is one of the most important parameters for holographic plate. Thin-film thicknesses of two types of holographic plates were measured by Michelson interferometer which took the white light as its incident source. By analyzing the errors of the results,the relation of the measurement errors to thin-film thickness and refractive index,and the applicable range of this method were studied. The result shows that with the increasing of film thickness,when it is from 8 μm to 41 μm,the absolute errors are ≤2 μm with little fluctuations,but the relative errors decrease from 14.1% to 2.2 %. The value of refractive indexes contributes to error propagation,and it is inversely proportional to absolute errors. In order to guarantee the validity of results,the thicknesses of films should be≥ 40 μm when the refractive indexes are about 1. 5. There are some advantages,such as a large measuring range,fewer experiment instruments and accurate result,when Michelson interferometer is used to measure some thicker thin films.