Laser TV

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Laser TV is a proposed new video display technology using laser optoelectronics. Although proposed as long ago as 1966[1], laser illumination remained too costly[2] and too poor in performance to viably replace lamps except in some rare ultra-high-end projectors[3]. At the Las Vegas Consumer Electronics Show in 2006, Novalux Inc., developer of Necsel semiconductor laser technology, demonstrated their laser illumination source for projection displays and a prototype rear-projection "laser" TV.[4] First reports on the development of a commercial Laser TV were published as early as 2006-02-16[5][6] with a decision on the large-scale availability of laser televisions expected by early 2008.[7] On January 7, 2008, at an event associated with the Consumer Electronics Show 2008, Mitsubishi Digital Electronics America, a key player in the LED laser market, unveiled their first commercial Laser TV, a 65" Full HD model.[8][9][10] First audiences who were shown reference clips from popular movies reported that they were blown away by a Laser TV's hitherto unseen color-display prowess.[11] Some even described it as being too intense to the point of seeming artificial.[12] These DLP-based rear-projection TVs are expected to go on sale in the third quarter of 2008 under the LaserVue[13] brand name. For plausibility, it may be worthy to note that Mitsubishi invented the first rear-projection television and was the first to sell a complete high-definition TV system in the U.S.[14] SYCO of China released a 120-inch Laser TV, the biggest in the world so far, and it will be used in cinema in late 2007.[1]

Contents

[edit] Technology

Lasers may become an ideal replacement for the UHP lamps[15] which are currently in use in projection display devices such as rear projection TV and front projectors. Current televisions are capable of displaying only half of the color gamut that humans can potentially perceive.[16] In contrast, proponents of Laser TV technology claim that the standard will be able to reproduce more than 90% of the colors visible to the human eye.

A Laser TV requires lasers in three distinct wavelengths: Red, Green and Blue. While red laser diodes are commercially available, there are no commercially available green and blue laser diodes which can provide the required power at room temperature with an adequate life time. Instead frequency doubling can be used to provide the blue and green wavelengths. Several types of lasers can be used as the frequency doubled sources: fibre lasers, inter cavity doubled lasers, external cavity doubled lasers, eVCSEL’s and OPSL’s (Optically Pumped Semiconductor Lasers). Among the inter cavity doubled lasers VCSEL’s have shown much promise and potential to be the basis for a mass produced frequency doubled laser.

A VECSEL is a vertical cavity, and is composed of two mirrors. On top of one of them is a diode as the active medium. These lasers combine high overall efficiency with good beam quality. The light from the high power IR-laser diodes is converted into visible light by means of extra-cavity waveguided second harmonic generation. Laser-pulses with about 10 kHz repetition rate and various lengths are sent to a Digital Micromirror Device where each mirror directs the pulse either onto screen or into the dump. Because of the well known wavelengths all coatings can be optimized to reduce reflections and therefore speckle.[citation needed]

[edit] Advantages

One major claim of laser advocates is the ability to produce undiluted, perfect colors allowing precise hue mixing. Advocates claim that 90% of the perceptible color gamut can potentially be reproduced.[17] Other improvements that laser advocates claim are bulbs that will never blow out, and increased efficiency by using two-thirds less power than traditional rear projection televisions.[16] Historically, however, lasers have been too bulky and expensive for widespread adoption.

The laser technology advocates claim that the technology will allow displays with a richer, more vibrant color palette than the conventional plasma, LCD or CRT displays.[16]

They also claim the displays will:[18]

  • be half the weight and cost of Plasma or LCD displays
  • require around 25% of the power required by Plasma or LCD displays
  • be very thin like Plasma and LCD displays are today
  • have a very wide colour gamutTwice the color of today's HDTVs.
  • have a 50,000 hour life
  • maintain full power output for the lifespan of the laser, resulting in a picture that doesn't progressively degrade over time, such as with plasma and LCD technology

[edit] Drawbacks

Together with the advantages of laser sources, there are reports that also describe some of the current shortcomings of laser displays,[19] such as the following:

  • Safety. The high power emitted by the coherent laser sources is inherently dangerous to human vision. Proponents claim that integrating the devices with the needed diffusion filters removes this risk.
  • Speckle. Due to the narrowband coherent light source, speckle will be an issue at the display. This has also been a problem in laser lighting displays and has been solved through modulation of the light source thus widening the bandwidth and reducing the possibility for coherent interference. Proponents claim that this issue can be minimized by the use of diffusing elements and multiple sources. These, however, may impact display resolution and system cost.

[edit] References

  1. ^ 2006 Laser Projection Systems Report. Insight Media (2006-02-02).
  2. ^ Big Blue Laser in a Small Package: Is it Coming Soon? - Greg Niven. Coherent Inc. (2003-02-01).
  3. ^ Z*Tron Vision projector (ZTV). Metatron Zone Management (2000-08-30).
  4. ^ Novalux Wins Insight Media “Best Buzz” Award at Consumer Electronics Show 2006. Insight Media (2006-02-01).
  5. ^ Mitsubishi Joins the Laser-TV Club. Display Daily (2006-02-16).
  6. ^ Mitsubishi Harnesses Colored Lasers to Produce New-Generation Lightweight HDTV. The New York Times (2006-04-03).
  7. ^ Laser TV Technology: Plasma and LCD Killer. Gizmodo (2006-10-11). Retrieved on 2007-01-04.
  8. ^ Mitsubishi Unveils Laser TV, 3-D Home Theater. MIT (2008-01-08).
  9. ^ HDTVs: Mitsubishi Laser TV's Colors Look Even Juicier Than the Girls on the Set. Gizmodo (2008-01-08).
  10. ^ Mitsubishi laser TV unveiled. Engadget (2008-01-08).
  11. ^ Color Burns Bright With Mitsubishi's Laser TV. Popular Science Blog (2008-01-09).
  12. ^ Mitsubishi Laser TV: Colors May Be Too Brilliant. Today @ PC World (2008-01-08).
  13. ^ Mitsubishi Digital Electronics America Introduces New Line of HDTVs Creating a New Dimension in Television. Mitsubishi Digital Electronics America, Inc. (2008-04-07).
  14. ^ Mitsubishi Digital Electronics America, Inc.. Mitsubishi Electric.
  15. ^ "The Technology Behind the Display", Novalux. Retrieved on 2007-09-04. 
  16. ^ a b c Morgenstern, Steve (2007). "Laser-Sharp Color". Popular Science 270 (1): 24. 
  17. ^ The Technology Behind the Display: Display Applications: Home Theater. Novalux. Retrieved on 2007-05-15.
  18. ^ Forget plasma and LCD TV - the Laser TV is coming!. iTWire (2006-10-11). Retrieved on 2007-01-04.
  19. ^ Brennesholtz, et al (2005-08-19). "Laser Projection Systems" (PDF). . Insight Media Retrieved on 2007-01-29.

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