公开(公告)号：US08817371B1

公开(公告)日：2014-08-26

申请号：US12512007

申请日：2009-07-29

申请人： Simon Andrew Boothroyd ,  Jerzy Adam Dobrowolski

发明人： Simon Andrew Boothroyd ,  Jerzy Adam Dobrowolski

IPC分类号： G02B5/30 ,  G02B27/28

CPC分类号： G02B27/283

摘要： A polarizing beam splitter has a pair of opposed transparent prism substrates with a refractive index n0, and providing at least one input port and at least one output port. The input port accepts light incident over a range of operational angles including a central operational angle. A multilayer thin film structure is sandwiched between the pair of opposed transparent substrates and consists essentially of a plurality of layers l1 . . . lm having respective refractive indices n1 . . . nm, wherein at least three of said refractive indices n1 . . . nm are different, and wherein the refractive index of the substrates n0 lies between the highest refractive index nH and lowest refractive index nL, and wherein nH, nL and n0 define a Brewster angle θ0B: θ 0 ⁢ B = arcsin ( n L ⁢ n H n 0 ⁢ n L 2 + n H 2 ) , and a critical angle θc: θ C = arcsin ⁡ ( n L n 0 ) . The refractive indices n0 and n1 . . . nm are selected such that the central operational angle for a beam incident on the multiple thin film structure lies above the Brewster angle θ0B and such that most or all the operational angles defined by said input port lie above the Brewster angle θ0B. For p-polarized light at least one optical admittance of the layers with refractive indices n1 . . . nm is lower or very close to that of the optical admittance of the substrate for the operational angles such that the thin film polarizing beam-splitter favors the transmittance for p-polarized light incident at that input port such that most of the p-polarized light is transmitted through the multiple thin film structure. For s-polarized light the polarizing beam-splitter acts as a high reflective coating to favor the reflectance for s-polarized light incident at the input port such that most of the s-polarized light is reflected from said multiple thin film structure. The polarizing beam splitter is compact and yet remains functional over a wide range of operational angles.