Sunday, December 15, 2013

An RGB Laser And Its Applications

By Cornelia White


A laser that emits three primary colors, red, green and blue is an RGB laser, the name coming from the three primary colors. These can be emitted in a single beam for all the three colors or a separate beam for each of the color. Through additive mixing which involves combination of the three basic colors at different frequencies, a number of several other colors can be obtained.

RGB laser sources have proven to perform better than other arc lamps beam sources. While the later are normally cheaper sources of beams, they come with limited lifetime, poor image quality and impossibility of high wall-plug efficiency. This is particularly as a result of poor spatial coherence and availability of less color space, a result of which has seen a rapid rise in their demand.

Beams from these sources are known to be coherent in both wavelengths, both in time and space allowing for inferences. If the change in phase properties is able to take place at the same time over a long distance and at the same period of time, then such waves will produce a very clear image. It is possible to cancel such waves with a similar with opposite phase.

These lasers are known to produce beams of the three primary colors with very narrow optical bandwidth making them close to the monochromatic light beams. They are thus capable of producing very clear images on mixing, the reason why they are getting more application like in cathode tube displays, color printers and lamp-based beamers.

These beam sources however are associated with low level power emission. With cinema projectors demanding 10 W for each color or more, these projectors have to be designed to meet this power demand level for them to be usable. Their level of power sufficiency, maturity and cost effectiveness are the major setbacks when it comes to their application.

External optical modulators are normally used in these types of beamers although RGB sources are fitted with power-modulators for better signals in situations where the optical modulator use is made impossible as a result of low power miniature devices. Laser diodes for instance are used to achieve modulation bandwidth between 10 to 100 megahertz or even much higher resolutions.

The red, green and blue lasers come in several types depending on the design and construction. One method involves the use of three different types of lasers with each emitting beam of a particular color. These forms of visible beam lasers are however not as suitable as the non visible ones that are near infrared in nature.

The use of infrared solid-state lasers involves application of a single laser that emits a beam of near infrared (invisible) nature. Such a beam then undergoes through several stages of nonlinear frequency conversion the end of which a three colored beam is produced. The other methods that have also been used to obtain these colors are the combination of parametric oscillators, the use of frequency doublers and the use of frequency mixers.

Technological advancement is however set to completely address the challenges in with an RGB laser. Just like other forms of lasers, they are set to be used in all other areas where there are need for lasers like in hospital machines, cutting technology and in entertainment industry among others.




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