23 May 2008
The "world's first source of truly broadband power" generates high-brightness output from the deep ultraviolet to the visible range and beyond.
Energetiq Technology, a US-based developer of short-wavelength light sources, has introduced a laser-driven lamp that delivers high-power, high-brightness emission at wavelengths ranging from 170 nm to beyond the visible range. It can be used as a broadband source for applications such as spectroscopy and biological imaging, and can also be tuned to emit a narrow range of wavelengths for specific applications.
In the laser-driven light source (LDLS) approach, a continuous-wave infrared diode laser is focused to a tight spot inside a specially designed bulb filled with xenon gas. The laser heats the gas to extremely high temperatures, creating a plasma less than 1 mm across that produces light with high efficiency over a broad spectral range.
The key advantage of this laser-based approach is that it eliminates the need for electrodes, which are needed in traditional arc and deuterium lamps to couple power to the plasma. Activating the gas with a laser leads to higher gas temperatures, which leads to higher gas temperatures, while the electrode-less design also avoids the major source of degradation and failure in traditional lamps.
According to Debbie Gustafson, the company's vice-president for sales and service, the technology has been shown in the lab to achieve continuous-wave broadband output using pump diode lasers with powers ranging from 50 W to many kilowatts.
Energetiq claims that their LDLS approach achieves both high brightness and high output power, unlike existing sources operating in the ultraviolet. "Mercury discharge lamps can deliver reasonable amounts of power concentrated in sharp emission lines, but have low brightness," said Gustafson. "Excimer lamps have low brightness and a low power density, and can only be used at discrete deep UV wavelengths."
Other options, such xenon and mercury short arc lamps, can offer high brightness in the visible and near-UV range, but according to Gustafson their output falls off rapidly in the deep UV spectral range. And deuterium lamps are limited in use to the deep UV range, as well as having low brightness.
What's more, says Gustafson, the fully integrated laser-based solution is much less expensive to buy and maintain than excimer and other deep-UV lasers. Potential applications include photoresist studies at 193 nm and 248 nm, deep UV microscopy, and spectroscopy at UV wavelengths.