A Light Guide Plate is an acrylic panel typically made from pure PMMA resin. PMMA is extremely transparent, highly weather resistant, and lasts longer than 30 years on average. On the bottom of the panel a matrix of lines can be etched, called V-Cutting, dots can be printed, a combination of both, or particulates are added into the panel itself. The purpose of all methods is to direct light out the front.
A v-shaped blade creates a grid on the bottom of the panel by etching a series vertical and horizontal lines. The depth and spacing of these lines is done meticulously as to optimize the evenness and the brightness of light released. The vertical V-grooves are widely spaced when they are close to the light source, but narrowly spaced when they are farther away from the light source. The horizontal V-grooves gradually grow wider and deeper as their distance from the light source increases. Therefore, the brightness of the front surface of the LGP is able to remain uniform.
A matrix of fine dots is printed onto the LGP using diffusive ink. These dots help scatter the light emitted from the light source. Dot printing is a quicker and cheaper process then V-cutting however not always the desired method. The major downside to dot printing is that ink is less effective at refracting light and therefore not as bright. Many backlighting applications require a very bright light that dot printing just can’t accomplish.
An increasingly popular third method is to add particulates to the resin itself. These minute particles are scattered throughout the panel and reflect light in all directions when combined with a light source. Using diffusion particles is an extremely efficient way to produce a LGP. Although, similar to dot printing, the particulates aren’t able to reflect as much light out of the front of the panel as V-cutting. For certain applications using a particulate infused LGP works well, backlighting printed graphics and for smaller applications for example. If a less transparent diffuser is being used and for larger projects, V-Cutting is almost always the preferred method.