Laser-phosphor technology: science fiction now science fact

Laser-phosphor technology is advancing rapidly. But what is it, what are the advantages of this technology and for what applications is it best suited?

There are many advantages of lamp-less laser-phosphor light source technology.  For example:
•    There is no lamp and therefore maintenance requirements are minimal
•    Brightness is more consistent than lamp-based projectors, which are subject to brightness fluctuations as the lamp is used (brightness decay) and replaced
•    It is quieter due to higher efficiency and so less requirement for cooling
•    Colour reproduction is brilliant
•    Due to the solid state light engine, the projector is able to operate in unusual positions, including portrait and downward projection

As a result of these benefits, laser-phosphor projectors are ideal for venues where ceilings are high and the projector is fairly inaccessible for maintenance, such as university lecture theatres, digital signage applications and museums/professional installations where usage hours tend to be higher and there are accessibility/maintenance restrictions.

It is also ideal for quieter environments such as smaller meeting rooms or those with low ceilings.

With such a wide choice of projectors – lamp-based, LED and laser - it is important to look at the application and venue to ascertain whether a laser-phosphor projector is the best solution.

If the projector is needed for lengthy usage with minimal downtime or the projector would be fairly inaccessible after installation, then this may be the best option.  

Also if colour accuracy is important, it may also be the best choice – although the colour performance of lamp-based DLP projectors varies with the type of colour wheel used. Some, like Optoma’s EH7700, provide colour wheels options so the colour performance and brightness can be tailored to the application – so it is important to look at all factors.

Optoma has recently expanded its range of laser-phosphor ProScene projectors with the 6,000-lumen ZU650 and the ultra-wide short throw, ZH300W.

The technical bit
Unlike the laser beams you may have seen in Bond films, no raw laser light is emitted from the lens of the projector.  So how does it work and what is the difference between laser and laser-phosphor projectors?

With a pure laser - the red, green and blue light from three laser diode arrays (one each for red, green and blue) is combined then passed through an optical diffuser. It is this diffused light that is used to illuminate the projector’s DLP chip and produce the image.
 
A laser-phosphor projector is slightly different in that it uses one blue laser.  This blue light is diffused and used as the blue light component to illuminate the DLP chip. The blue laser is also used to energise a phosphor wheel that emits yellow light. This is then split into its red and green components and used to illuminate the DLP chip.

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