Liquid crystal displays (LCDs) are ubiquitous nowadays as a display technology. The most prominent applications in the commercial sector include computer monitors, cellular phones, televisions, and handheld digital devices.

The majority of LCDs are illuminated from the rear to provide lighting when ambient conditions are insufficient. The two illumination schemes employed are bottom-lit and edge-lit.

The bottom-lit configuration uses an array of sources, such as light emitting diodes, or one uniform source, such as an electro-luminescent panel, placed behind the LCD. This configuration gives excellent uniformity and brightness, but requires more energy and thicker housing.

 
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The edge-lit design uses a wedged guide to distribute light from a source placed beside the LCD display. This configuration uses less energy and can be housed in a thinner package, but sacrifices uniformity and brightness.

 
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ZEMAX has the capability to model either illumination scheme, however, the edge-lit configuration poses a more involved design problem, and this will be the focus of the article. We will ignore the actual liquid crystal layer and consider only the backlight design.