An Image Quality Wire-Grid Polarizing Beam Splitter

A couple of years ago, MOXTEK introduced its ProFlux™ wiregrid polarizer for use in Liquid Crystal projection displays. These polarizers have boasted high durability as well as high performance and purity of the resultant polarization state. More recently, we introduced a version of ProFlux™ optimized for use as a polarizing beam splitter (PBS), including an optically flat PBS for applications that reflect an image. Performance of the ProFlux™ PBS will be discussed in this paper, from throughput and contrast to polarization purity and its interaction with liquid crystal panels that make it a nearly ideal polarizer for liquid crystal projection applications. Many people have reported contrast exceeding 15,000:1 when used in a configuration as in Figure 1 that transmits light through the PBS, reflects from a mirror [with quarter-wave plate (QWP) to produce the bright state], and then reflects from the PBS onto a detector. Contrast values exceeding 2000:1 have been reported in a similar configuration when using an LCOS panel instead of the mirror-QWP. These results are much higher than have been reported with conventional PBS solutions or even with other newer devices, and merit some explanation.