摘要 |
<p>The present invention relates to an apparatus and method for measuring physical properties of an object (25), such as thickness, group index of refraction, and distance to a surface. The apparatus includes a non-coherent light interferometer (53) and a coherent light interferometer (55) in association so as to share a variable optical path delay element (54). Thickness measurements can be made, for example, of solids, liquids, liquids moving along a horizontal plane, or liquids flowing down a plane. Thickness measurements of multiple layers can be made. <IMAGE></p> |