| 摘要 |
PURPOSE:To improve mechanical strength and resistance to environmental effects by utilizing a refractive index distribution formed by the diffusion of atomic ions in a transparent substrate as hologram having lens effect. CONSTITUTION:A patterned mask 7 is deposited on the surface 6a of a transparent substrate 6. Suitable material to be used for the mask is different depending on the kind of an ion source 9 which exchanges ions feeding ions through an opening part 8. For example, when molten salt is used for the ion source 9, titanium can be used for the mask 7. The transparent substrate 6 covered by the mask 7 is allowed to contact with the ion source 9, and atomic ions 10 from the ion source 9 are diffused into the transparent substrate 6 through the opening part 8. Since the atomic ions 10 have different electronic polarizability, etc., from atomic ions constituting the transparent substrate 6, a refractive index distribution 11 is formed in the transparent substrate 6 basing on the distribution of concn. of the atomic ions 10. A hologram lens is formed by removing the mask 7 by etching or polishing from the transparent substrate 6 having a refractive index distribution 11 which has been formed thereon.
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