Polarizing plate, optical apparatus and method of manufacturing polarizing plate

An optical apparatus comprising a liquid crystal panel and two polarizing plates having a wire grid structure, wherein at least one of the two polarizing plates comprises:

• a transparent substrate;
• and
• a plurality of protrusions configured to extend in a first direction on the transparent substrate, and periodically arranged at a pitch shorter than a wavelength of light in a use band, wherein each of the protrusions includes a reflective layer, a multilayer film, and an optical property improving layer located between the reflective layer and the multilayer film,
• the multilayer film is formed of a dielectric layer, an absorption layer and a second dielectric layer from the vicinity of the transparent substrate in that order,
• the optical property improving layer is formed of an oxide that contains a constituent element of which the reflective layer is composed, in which the oxide is different from the material of the dielectric layer, and
• the optical property improving layer is formed of a material whose etching rate with respect to a chlorine-based gas method is no less than 6.7 times and no more than 15 times an etching rate of the material of the multilayer film with respect to the same chlorine-based gas method, wherein the dielectric layer is in contact with the optical property improving layer and wherein the polarizing plates are disposed on incident and outgoing sides of the liquid crystal panel.