| 摘要 |
PURPOSE:To reduce the parts number of an expensive dichroic mirror by providing composite dichroic film formed the plural dichroic films of which dichroic characteristic are different on a common substrate. CONSTITUTION:The left half S1 and the right half S2 of the common glass substrate 13 of first and second composite dichroic mirrors 11 and 12 is respectively coated with coating of which characteristic is different. For example, the left half of the common glass substrate 13 of the second composite dichroic mirror 12 is coated with the coating 14 which reflects blue, the right half is coated with the coating 15 which reflects red. Then the left half composes the dichroic mirror which reflects blue and the right half composes the dichroic mirror which reflects red. The whole surface of the glass substrate 13 of the first composite dichroic mirror 11 is coated with the coating 14 which reflects blue and then, only the left half is coated again with the coating 15 which reflects red. Therefore, the right half composes the dichroic mirror which reflects blue and the left half composes the dichroic mirror which reflects blue and red.
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