| 摘要 |
Provided is a light-shielding material for use in optical instrument and having a light-shielding sheet with broad low-gloss region while maintaining the physical properties necessary for a light-shielding sheet. The light-shielding material 1 comprises a light-shielding sheet 4 on a substrate 2, and the surface properties of the light-shielding sheet 4 are adjusted so as to fulfill at least one of A1 and A2, and at least one of B1 and B2. A1 is the condition that the arithmetic average roughness Sa in a three-dimensional surface roughness measurement is 0.4 or larger and 2.0 or smaller, A2 is that the ten-point average roughness Sz in a three-dimensional surface roughness measurement is 1 or larger and 20 or smaller. Defining a central plane of projections and recesses in a three-dimensional surface roughness measurement as a reference plane, Pn (n is any positive integer) as the number of projections which protrude to a plane located at a height of n times Se from the reference plane, Pn+1 as the number of projections which protrude to a plane located at a height of (n+1) times Sa, and Rn as the ratio (Pn+1/Pn) of Pn and Pn+1, B1 is the condition that R1 is 55% or greater and R4 is 7% or greater, and B2 is the condition that at least R1 is 55% or greater, R2 is 15% or greater and R3 is 8% or greater. |
