Cube, Polarizing Beam-Splitter with Reduced Incident-Angle

A cube, polarizing beam-splitter (PBS) comprising:

• a) a first prism including two ends linked by an inner face, a first side, and a second side;
• b) a second prism including two ends linked by an inner face, a first side, and a second side;
• c) a polarizer sandwiched between the inner face of the first prism and the inner face of the second prism;
• and
• d) a first angle, between a plane of the first side of the first prism and a plane of the inner face of the first prism, having a value of between 10 degrees and 42.5 degrees;
• e) a second angle, between a plane of the second side of the first prism and a plane of the inner face of the first prism, having a value of between 10 degrees and 42.5 degrees;
• and
• f) |Eff−16−Eff+16|<0.25 across a wavelength range of 400 through 700 nanometers, where:
• i) Eff−16 is an efficiency of the cube PBS with an angle of incidence on the polarizer equal to the first angle minus 16 degrees;
• ii) Eff+16 is an efficiency of the cube PBS with an angle of incidence on the polarizer equal to the first angle plus 16 degrees;
• and
• iii) efficiency means a fraction transmission of a predominantly-transmitted polarization times a fraction reflectance of an opposite polarization.