The blocking method has found its way into liquid crystal displays (LCDs), video projectors and rear projection TVs.
The light valve thus consists of the two polarising filters, where one has a voltage controlled switch function thanks to the properties of the liquid crystals.
The portion of light that is reflected on the target decides the gray scale.
Should this happen at too low a frequency, the human eye and brain would perceive it as flickering, but due to sufficiently high frequency, a human will be "tricked" into viewing it as a continuum, a smooth shift in brightness.
Examples of the reflective LV type are the digital micromirror device (DMD), Eidophor's oil-film based system,[1] and the grating light valve.