| 摘要 |
PURPOSE:To safely produce the title distributed refractive index type plane lens with a simple method by depositing a dopant consisting of metal on a transparent dielectric having a flat surface and diffusing the deposited layer into the dielectric with heat, etc. CONSTITUTION:A metallic mask 12 of Cr, etc., having a circular opening 13 consisting of conical surfaces 13a and 13b is laid on a substrate 11 of LiNbo2 whose one surface is optically polished and having a flat surface. Under such conditions, Ti is deposited by sputtering on the surface of the substrate 11 to form a deposited layer 14 having an approximately spherical surface in the circular opening 13. Then the mask 12 is removed, heat treatment is carried out at a specified temp. and the deposited layer 14 is diffused into the substrate 11. Moreover, thermal diffusion is performed while sending gaseous O2 to replenish the oxygen of the crystal and a distributed refractive index type microlens 15 is formed in the substrate 11.
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