| 摘要 |
PURPOSE:To increase accuracy in overlapping lattice patterns in the ion exchange area of a first layer and in the phase compensating film of a second layer in a hologram having two-layer lattice structure. CONSTITUTION:An ion exchanging area 3 is formed on a lithium niobate substrate 1 with using an ion exchanging mask 2. Then the surface is wholly coated with a photoresist film and exposed to light from the back surface 5 and developed. The ion exchanging mask 2 is etched from side area to make the pattern width same as that of the ion exchanging area 3. Then a phase compensating film 6 is formed with using this ion exchanging mask 2. |
