| 摘要 |
PROBLEM TO BE SOLVED: To obtain a fine contrast interference fringe and measure a measured surface shape with high accuracy even in the case an aspherical surface is measured using Fizeau interferometer. SOLUTION: The measurement device is constituted with a light source 1 emitting luminous flux, a luminous flux dividing member 14 dividing luminous light form the source 1 into reference light and measuring light introducing to a measured surface, an interference detection part 11 detecting an interference fringe between the reference light and the measuring light from the measured surface, and an arithmetic part 12 calculating the surface shape of the measured surface based on the interference fringe. In this case, the dividing member 14 contains diffracted optical elements 16-18, where light reflected at the elements 16-18 is set as the reference light and light diffracted from the elements 16-18 is set as the measuring light. The elements 16-18 have a substrate 18, at least a first thin film layer 17 formed with a first medium, and a second thin film layer 16 formed with a second medium.
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