Optical element, light diffusing element, and image display apparatus

摘要

An optical element using visible light from wavelengths λS to λL (λL>λS), is formed of a translucent material having refractive indexes nS and nL, respectively, for light having the wavelengths λS and λL. The optical element includes an incident face; an exit face; and a micro convexo-concave structure used as an anti-reflection structure (ARS), being formed at least one of the incident face and the exit face. An average distance P between adjacent micro convexo-concave structures satisfies condition (1) P≦0.8·λS/nS. Dimensionless parameters mS and mL satisfy condition (2) 0.8≦mS≦1.1 and condition (3) 0.8≦mL≦1.1. The parameters mS and mL, an average height H, the wavelengths λS and λL, and the refractive indexes nS and nL of the micro convexo-concave structure satisfy condition (4) mS·λS/(2·nS)≦H≦mL·λL/(2·nL).

主权项

1. An optical element using visible light of a wavelength range of from a wavelength λS to a wavelength λL, the wavelength λL being greater than the wavelength λS (λL>λS), the optical element being formed of a translucent material having a refractive index nS and a refractive index nL, respectively, for light having the wavelength λS and light having the wavelength λL, the optical element comprising:
an incident face; an exit face; at least one of the incident face and the exit face being a flat face; and a plurality of micro convexo-concave structures, used as an anti-reflection structure (ARS), formed on at least the flat face, an average distance P between adjacent micro convexo-concave structures satisfying condition (1),
P≦0.8·λS/nS,  condition (1) dimensionless parameters mS and mL satisfying condition (2) and condition (3),
0.8≦mS≦1.1  condition (2)0.8≦mL≦1.1,  condition (3) the parameters mS and mL, an average height H, the wavelength λS and the wavelength λL, and the refractive index nS and the refractive index nL of the micro convexo-concave structure satisfying condition (4),
mS·λS/(2·nS)≦H≦mL·λL/(2·nL).  condition (4)