Originally Published MPMN June 2009

BREAKTHROUGHS

Plasma Lamp Outperforms Xenon and LEDs

Stephanie Steward

Potentially suited for use in such invasive medical devices as endoscopes, laryngoscopes, arthroscopes, and a variety of other scopes, Solid-State Plasma LIFI bulbs from lighting component manufacturer Luxim Corp. are offered as an efficient, stable, and long-lasting alternative to existing lighting options. The pill-sized bulbs are currently offered for such medical applications as surgical headlamps, fluoroscopy, and microscopy products.

LIFI light sources feature a solid-state amplifier that drives a high-intensity plasma emitter by generating and guiding a radio-frequency signal into an electric field around the bulb. The high concentration of energy in the electric field vaporizes the contents of the bulb into a controlled plasma state at the bulb’s center. The controlled plasma generates the bulb’s intense light, resulting in a high number of lumens. A single LED suited for medical device applications tends to have lumens numbering in the hundreds, whereas LIFI bulb lumens number in the tens of thousands, making them significantly brighter than LEDs.
Providing a full-color spectrum for sharp visuals, the LIFI lamps also demonstrate much higher efficiency for their lifetime than do xenon bulbs, according to marketing manager Apurba Pradhan. “Xenon lighting lasts about 1000 hours and can quickly degrade in quality and output over time,” he says. “LIFI bulbs provide more-consistent light quality over a much longer lifetime.”
Moreover, the electrodeless plasma bulbs offer a higher level of reliability than bulbs that contain electrodes or filaments, especially those that contain mercury. Explosions and potential failures are possible in xenon and mercury bulbs because of the presence of electrodes and glass-metal seals under high pressure. The electrodeless cavity coupling of power into the LIFI bulbs results in significantly lower failure rates, according to Pradhan.
The LIFI bulbs’ reliability also does not diminish over their long lifetime, whereas other bulbs can become less powerful over time. Xenon bulbs with wattages ranging from 200 to nearly 400 can only last up to 2000 hours. They also have higher rates of color shift and potential for flickering. However, one LIFI bulb with 250 W of ac power lasts for 10,000 hours with a color shift of only 0.15 K/hr and a flicker value of less than 0.5% rms. The LIFI’s low rms flicker value means that it provides a better signal for image capture, virtually eliminating the potential for noise, flickering, or variation in intensity, according to Luxim. This enhanced signal-to-noise ratio is beneficial for sensitive applications requiring visualization and digital imaging.
The bulb’s reliability and signal-to-noise ratio also allow for highly detailed analytical microscopy images to be taken with small exposure times. For microscopy and fluoroscopy applications, the bulb’s light source is filtered through ultraviolet, infrared, and other color filters to accommodate the fluorescence characteristics of various tissues. Some tissues may show certain fluorescence characteristics under green light and not red light, for example. “Therefore, it is important that the source has a broad spectrum and can provide any wavelength of light with adequate intensity at each wavelength,” says Pradhan.

Luxim Corp.
Sunnyvale, CA
www.luxim.com
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