Laser TV: Laser beams could revolutionise television
By Simon Blohm
In many Internet technology portals, blogs and numerous forum contributions, there have been many articles on the topic of laser TV lately; that which sounds like a futuristic technology from a science fiction novel is actually a new development in the area of entertainment electronics. Laser TV sets are reputed to provide better image quality and to be longer lived, better at conserving energy and more efficient – the list of advantages goes on and on.
But how can you explain the functionality of a laser simply and comprehensibly, given that the normal customer without a scientific background generally knows laser technology only from STAR WARS films – and then, in the form of a light sabre. For this reason, we will first explain how this new technology works.
The image of a laser television is constructed in a similar manner to than on a back projection television. The image is routed to a mirror system via an internal projector and projected onto the screen from behind. The individual points of light used for mixing the various colours are created directly from red, green and blue laser beams.
The semi-conductor laser creates an infrared light which is not visible to the human eye. By using particular crystals using which the laser beam is channelled, it is possible to change the infrared light into light that is visible to humans. The light created is red, green or blue – the colours from which the image that we as "viewers" see is composed.
This process takes advantage of the special physical characteristics of the crystals, which are usually composed of lithium and niobate. They allow almost all colours in the colour spectrum of light that is visible to human eyes to be created. Depending on the wavelength and frequency of the light beam created, even the finest hues of colour can be displayed – something which is not possible on conventional plasma or LCD TV sets.
Functionality of laser technology (Picture: Oerlikon Optics)
The semi-conductor chips contain numerous laser diodes so that the individual components can be kept relatively compact. The company Novalux Inc. claims that it can check the functionality of the diodes during the production process even before the wafers are split and can therefore minimise both the failure rate and production costs, which in turn has a positive effect on the customer’s wallet and ensures good quality.
The laser beams are created in a laser diode field which sends the light in a vertical direction rather than to the side. This means that every laser diode can radiate light of up to 100W but the diode is not strained too much and is therefore seldom destroyed. According to the manufacturer, no cooling period is necessary.
Various colours are created in the laser ray of a laser TV and are then used to create a coloured light pixel via a micro display. (Photo: Novalux)
The laser beams are projected onto a micro display (DLP) and, depending on the colour and brightness of the pixel which should be displayed, the laser beams are produced in different proportions. The matrix of micro-mirrors of which a micro display is composed swings back and forth a thousand times per second; the micro mirrors swing and direct the laser beam from left to right and from top to bottom on the projection surface.
A laser TV can project onto any white surface and in a format that cannot be achieved with traditional televisions. From a distance of 40 metres, a screen diagonal of six metres can be created. The tiny laser point moves across the projection surface at a speed of over 90 km/h and writes the image to the projection surface similarly to the electron ray in tube monitors.
The size of the laser point is just as big at a distance of three metres as it is at 300 metres and the composition of the projection surface has no influence – it doesn’t matter if the beam is projected onto a curved or flat surface. The image retains its sharpness and quality. In addition, the laser television outdoes conventional TV sets, even the latest models on the markets, especially in colour reproduction and contrast.