| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus capable of performing nondestructive measurement of the refractive index distribution of an inspected material comprising a GRIN lens (graded refractive index lens), regardless of the shape of the lens. SOLUTION: An inspected material (A) dipped in a reagent (B) of an approximately equal refractive index is caused to transmit a coherent light emitted from a light source 1, and it is superposed with a reference light and an interference fringe image is formed on an interference fringe detector 15, and a transmitted wave surface W(x) is found from this interference fringe image. On the other hand, a reference transmitted wave surface Wo(x) is computed form design values of the substance to be inspected. Besides, the thickness d(x) in the optical axis of the inspected material is found similarly from the design values of the inspected material, and the refractive index differenceΔn(x) in an arbitrary cross section is found from the next equations.ΔW(x)=W(x)-Wo(x),Δn(x)=ΔW(x).λ/d(x) whereλis the wavelength of the coherent light.
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