ND FILTER AND LIGHT QUANTITY ADJUSTING DEVICE USING THE SAME

PROBLEM TO BE SOLVED: To provide a neutral density filter (ND filter) in which resolution does not deteriorate even when it is used for an imaging optical system and which has excellent durability. SOLUTION: In the ND filter where light absorption films 3, 5 and dielectric films 2, 4, 6 are stacked on a transparent base material 1, the transparent base material 1 is an amorphous transparent film which is synthesized with norbornenes as a monomer and which has alicyclic structure in a main chain. The amorphous transparent film is transparent at least at a visible range, haze value is 1% or less and retardation value is 20 nm or less. Thickness of the amorphous transparent film is within a range between 50 μm and 200 μm. The light absorption films 3, 5 are composed of a simple substance or its compound chosen from Ti, Cr, Ni, NiCr, NiFe and NiTi. The dielectric films 2, 4, 6 are chosen from SiO2, Al2O3, MgF2, TiO2and CeO2. COPYRIGHT: (C)2008,JPO&INPIT