Microspectrophotometers are used to test the color and intensity of each LCD pixel
Typical test spectra from a liquid crystal display
LCD Metrology: Color, relative intensity, spectroscopy and film thickness of pixels and light sources.
Liquid Crystal Display, or LCD, is a device that consist of a light source covered by a series of colored "pxels" arranged in a pattern on a color mask. A liquid crystal layer is controlled with electronics and acts as a shutter for each pixel. These can be turned on and off rapidly and thus are commonly used for high resolution displays. As these pixels are getting smaller and smaller, especially with the latest generation of microdisplays, color consistency and intensity are presenting ever difficult quality control challenges.
Due to the nature of flat panel displays, they are manufactured with hundreds of rows of microscopic pixels to be deposited on a surface. In the next generation of microdisplay, such as those used in MP3 players and mobile phones, these pixels can be as small as 10 microns across. Quality control of both the components and completed LCD devices is done by optical microspectroscopy. Microspectrometers, such as those made by CRAIC Technologies, are used to measure the color and the intensity of the output from individual pixels and from groups of pixels. They are can be used to map the color and intensity outputs of individual pixels or even entire displays. This is important as manufacturers of flat panel displays need to make sure that all the different types of pixels are the same color and brightness. A microspectrophotometer does this quickly and easily.
Learn about microscale LCD testing and analysis: