| 摘要 |
PROBLEM TO BE SOLVED: To provide an ND filter with an IR cut function capable of contributing to appropriate transient light quantity adjustment when being incorporated into an optical device.SOLUTION: An ND filter 1 includes a light transmissive substrate 10, an ND film 20 formed on the surface of the substrate 10 and adjusting a transmitted visible light quantity, and an IR cut film 22 formed on the surface of the substrate 10 where the ND film 20 is formed or the surface of the ND film 20 and adjusting a transmitted infrared quantity. The ND film 20 is formed so as to cover the whole area of the substrate, and has a gradient transmittance so as to change its light transmittance gradually. |
