| 摘要 |
PROBLEM TO BE SOLVED: To improve the use efficiency of light and to produce a device at a low cost by using an optically anisotropic polymer produced by polymn. of polymerizable liquid crystal monomers to form a diffraction grating. SOLUTION: A polyimide film 4 is formed on the surface (A) on the side of an optical disk 9 of a glass substrate 3, and nematic liquid crystal monomers are oriented on the film 4. A photomask with a pattern of a diffraction grating plotted is disposed near the liquid crystal monomer film and the monomer film is exposed to UV rays to form an optically anisotropic polymer film. Then monomers not polymerized are dissolved with a solvent to form an optically anisotropic diffraction grating comprising the optically anisotropic polymer 5. The rugged part in the grating is filled with an isotropic photopolymer 6 having almost the same refractive index as that of normal light. Further, a λ/4 wavelength plate 7 is laminated thereon to produce a package. The optical head device using the optically anisotropic diffraction grating can be mass-produced in a large substrate area without using a material such as double refraction crystal, and a higher light use efficiency can be obtd. compared to an isotropic diffraction grating. |
