Optical film, polarizing plate, liquid crystal panel, and image display apparatus

An optical film comprising:

• a light transmissive base material;
• and a functional layer disposed on the light transmissive base material, wherein:
• the functional layer has a concavo-convex surface forming a surface of the optical film;
• the functional layer comprises a hard coat layer having a concavo-convex surface, and a low refractive index layer conformally disposed on the concavo-convex surface of the hard coat layer and having a lower refractive index than that of the hard coat layer;
• the hard coat layer comprises a binder resin and inorganic oxide fine particles having an average primary particle diameter of 1 nm or more and 100 nm or less;
• the hard coat layer does not comprise any particles other than the inorganic oxide fine particles and aggregates thereof;
• a root mean square slope RΔq of a roughness curve on the concavo-convex surface forming the surface of the optical film is 0.0005 or more and 0.0026 or less;
• an average spacing Sm of concavities and convexities that constitute the concavo-convex surface forming the surface of the optical film is 0.20 mm or more and 0.60 mm or less;
• in a state in which the concavo-convex surface forming the surface of the optical film is irradiated with parallel light travelling in a direction sloped at 10° with respect to a normal direction of the optical film, in an angle distribution of a reflected light intensity measured in a plane including both directions of the normal direction and the travelling direction of the parallel light, using a detector with a light receiving diaphragm of 4.0, a value obtained by subtracting a width of an angle region, in which a reflected light intensity that is not less than ½ of a maximum reflected light intensity is measured, from a width of an angle region, in which a reflected light intensity that is not less than 1/100 of the maximum reflected light intensity is measured, is 0.7° or more and 1.4° or less;
• and
• the detector is GP-200 manufactured by MURAKAMI COLOR RESEARCH LABORATORY.