WIRE GRID TYPE POLARIZING ELEMENT

To provide a wire grid type polarizing element with which it is possible to maintain the light beam transmittance required for high degree of polarization and specifically suppress reflectance on the reverse side rather than on the surface.SOLUTION: Provided is a wire grid type polarizing element with which the average width (a) of a metal reflector is 200 nm or less, and the ratio (b/a) of the average thickness (b) of the metal reflector to the average width (a) from the sheet surface side to the tip in reverse side direction is in the range 4 to 25. Furthermore, a cross sectional shape either parallel or perpendicular to a mono-dimensional grid array direction in the vicinity of the tip part in thickness direction of a metal reflector (B) is gradually narrowed in linear or smooth curved form as it comes close to the tip, and the ratio (c/a) of the average length (c) in tip direction of a portion (D) that is gradually narrowed as it comes close to the tip to the average width (a) is 1.2 or greater.SELECTED DRAWING: Figure 2 【課題】 高偏光度で必要な光線透過率を維持して、表面側と裏面側のうち特に裏面側反射率を抑制できるワイヤグリッド型偏光素子を提供する。【解決手段】 金属反射体の平均幅（ａ）が２００ｎｍ以下で、シート表面側から裏面方向先端までの該金属反射体の平均厚み（ｂ）と前記平均幅（ａ）の比（ｂ／ａ）が４〜２５の範囲内にあり、かつ金属反射体（Ｂ）の厚み方向先端部近傍における、一次元格子状配列方向と平行及び垂直の少なくともいずれか１つの断面形状が先端にいくほど直線状ないし滑らかな曲線状で徐々に細くなっていて、この先端にいくほど徐々に細くなっていく部分（Ｄ）の先端方向への平均長さ（ｃ）と前記平均幅（ａ）の比（ｃ／ａ）が１．２以上である、ワイヤグリッド型偏光素子。【選択図】図２