To provide an optical low-pass filter or the like including a phase grating having low incident angle dependency and high moire removing performance over the whole region.
The optical low-pass filter 1 is a thin plate-like optical low-pass filter including an index modulation type diffraction grating layer including a matrix layer 2 composed of a cured object of a photo-polymerization composition and a plurality of columnar structures 4 having a refractive index different from that of the matrix layer. The columnar structures are oriented to extend in the thickness direction of the matrix layer inside the matrix layer, and arrayed in a grid-like state in a plane perpendicular to the thickness direction of the matrix layer, and the array pitch Λ and height H of the columnar structure satisfy the following relationship: H/Λ<7, and also, the diffraction efficiency η is 10% or more and 75% or less.
HATTORI TOSHIAKI
SANETO KOICHIRO
Disciple Maru Ken
Ino Sato
Mitsuru Matsushita
Ichiro Kurasawa