| 摘要 |
PROBLEM TO BE SOLVED: To obtain a non-polarizing beamsplitter with high performance by reducing the number of Al<SB>2</SB>O<SB>3</SB>thin film layers. SOLUTION: A non-polarizing beamsplitter includes thin film groups and one or more additional thin films (220-X, 220-Y, 520-Z, 720-R and 720-S). Each of the thin film groups by itself fails to provide a non-polarizing reflection, but the combination of the thin film groups and the additional thin films provides a non-polarizing reflection. Each thin film group can consist of four layers, one layer (H) of a higher refractive index material, two layers (M) of an intermediate refractive index material, and one layer (L) of a lower refractive index material, and at least one of the additional thin films is made of a material (X) not used in the thin film groups. The additional thin films (520-Z, 220-X and 720-R) can precede, be in between, or follow the thin film groups along the path of light through the beamsplitter. COPYRIGHT: (C)2004,JPO
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