Optical structure including half-silvered mirror and selective reflection film in combination

An optical structure comprising a half-silvered mirror and a selective reflection film in combination, wherein

• the half-silvered mirror includes a first support member and a partial reflection film stacked on a back surface of the first support member,
• the partial reflection film reflects external light incident from a front surface side of the first support member to present a mirror image on the front surface side of the first support member,
• the selective reflection film is provided further to a back surface side of the half-silvered mirror so as to be opposed to the partial reflection film,
• throughout a visible light range of 400 nm to 750 nm, the selective reflection film more readily transmits one of left-handed circularly polarized light and right-handed circularly polarized light, which is hereinafter referred to as F polarized light, than the other, which is hereinafter referred to as R polarized light, and more readily reflects the R polarized light than the F polarized light,
• a reflectance of the selective reflection film for the R polarized light is higher than a reflectance of the partial reflection film for the F polarized light throughout the visible light range,
• an air gap layer being vacuum or including a space filled with gas is provided between the selective reflection film and the partial reflection film,
• the optical structure further comprising a second support member opposed to the first support member, wherein
• the selective reflection film is stacked on a front surface of the second support member,
• a protection film is further formed on a front surface of the selective reflection film,
• a thickness of the second support member is 0.5-3 mm, and
• wherein the selective reflection film and the partial reflection film are separated from each other by the air gap layer across an entire region in which the selective reflection film and the partial reflection film overlap, the air gap layer is a continuous cavity having a uniform thickness greater than 0 mm, the thickness of the air gap layer is less than one-half of the thickness of the first support member, the selective reflection film and the partial reflection film are substantially parallel to each other, and the air gap layer is configured such that first-order and second-order ghost images generated by reflections at interfaces do not overlap.