Antireflection
Beamsplitter
Reflector
Bandpass
Miscellaneous 
New Thin Film Polarizing BeamsplitterIn the paper*, given at the Optical Interference Coatings conference in June 1998, the authors discuss a new design for a highperformance polarizing beamsplitter based on frustrated total internal reflection. This polarizer has the following advantages: nonabsorbing, broad band, wideangle, and high extinction ratios (Ts/Tp and Rp/Rs). The diagram below illustrates the operation of this polarizer.
The coating is sandwiched between two prisms. Note that S polarized light is transmitted, which is the opposite of other designs. Also, note that light strikes the coating at a very high angle. Although the authors do not give the exact details of the coating design, it is possible to use TFCalc to create such a polarizer. Here we design a polarizer for 400700 nm to operate for the angles 6575 degrees in the prism. This design requires a highindex glass prism. An index of 1.85 is used in this design. This means that the range of angles in air is ｱ9.28, which is considered wideangle. We use the following 22 continuous optimization targets:
There are many ways to design this coating. One simple method is to start with a stack such as (0.5H L 0.5H)^n that reflects the P polarization for the wavelengths and angles given above, and then use optimization to force the coating to transmit S polarization. Here H and L represent quarterwave layers of index 2.35 and 1.45, respectively. Some tests show that if we start with the 21layer design created by setting n=10, then the optimization targets given above will be met. The performance is shown below, with the left scale for the optical density of P reflectance and the right scale for S transmittance. The extinction ratio is greater than 1000 for all design angles and wavelengths.
Here is the design, with the first layer closest to the substrate and thickness given in nm: H 11.16 L 48.87 H 35.94 L 68.58 H 39.50 L 79.77 H 46.20 L 96.61 H 49.71 L 102.74 H 50.49 L 102.74 H 49.71 L 96.61 H 46.20 L 79.77 H 39.50 L 68.58 H 35.94 L 48.87 H 11.16 Note, curiously, that optimization preserved the symmetry of the original design (i.e., layers 1 and 21, 2 and 20, 3 and 19, etc., have the same thickness). The authors are commended for this ingenious polarizer, which is the subject of a patent application. However, it seems that this polarizer has two drawbacks: (1) the dimensions of the prisms may prevent its use in some applications and (2) the prisms seem to require a highindex glass, which presents other problems. *Recently, a paper was published that gives much more detail about this polarizer. See

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