| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for the simultaneous measurement of the refractive index and the thickness of an object to be measured, by a light interference method which can perform a high-speed measurement. SOLUTION: A low-coherence light interference measuring means which is equipped with a first beam splitter and a first photodetector is provided. A confocal optical measuring means which is separated from the low-coherence light interference measuring means and which is equipped with a second beam splitter and a second photodetector is provided. In an actual measurement, a stage 104 on which a sample 105 is mounted is moved once to the z-direction at a speed of 1 mm/sec or more. Two quantities Δz, ΔD (=ng×t) which are required for simultaneously measuring the refractive index n and the thickness t of the sample 105 can be measured. On the basis of an expression which approximately expresses a relationship between the phase refractive index np and a group index ng of the sample and on the basis of a relational expression of the np, the ng, the t and the Δz, the ΔD, the refractive indexes np, ng and the thickness t of the sample 105 can be decided on the basis of the two measured quantities Δz, ΔD. The time required for simultaneously measuring the refractive indexes and the thickness serially is at one second or less, the measurable thickness of the sample is at 20 μm to several mm, and the measuring accuracy of the sample is at 0.2% or less in a thickness of 0.1 mm. |
