A novel optical monitor helps fend off laser breakdowns before they happen.
By Joan Zimmermann/
jzimmermann@nttc.eduNovaWave Technologies (Redwood City, CA) has developed a real-time optical-health monitoring system, dubbed a “Canary in a Beam Line,” to fend off damage to laser components before it’s too late.
Based on a Phase II SBIR supporting the Airborne Laser (ABL) program, the system comprises an optical cavity that uses an optical coating very similar to that used in the ABL’s laser. When conditions are such that the cavity begins to deteriorate due to accumulation of contamination, the operator is immediately alerted, fast enough to avoid damage to the primary laser optics. The monitoring system functions on a microsecond timescale, can operate continuously for months at a time, and can detect destructive gases or particulates at parts-per-million to parts-per-billion sensitivity levels.
NovaWave’s monitoring technology has roots in the Airborne Laser program, which incorporates a high-power laser in the nose of an airplane to defend against missile threats. The SBIR award included plans for a commercial version of the device, which in its current form is highly specific to the ABL system in terms of its rigorous specifications, and is being considered for insertion through a Phase III project. Researchers for the Defense Department’s Advanced Tactical Laser program also have expressed interest in the sensor for land-based and airborne systems. In the future, a commercial version of this system could be useful for the in-situ monitoring of high-power commercial lasers such as those used in semiconductor fabrication and industrial welding.
The Canary system is based on cavity ringdown (CRD) spectroscopy, wherein a laser is injected into an optical cavity, quickly turned off, and the optical cavity “decay time” is measured. The high reflectivity of the mirrors in the cavity translates into high sensitivity to changes in the optic performance. The Canary cavities are extremely compact, all-fiber coupled, permanently aligned, and user-serviceable in a rapid fashion. Because the system is fiber-optic-based from end to end, it is also impervious to electromagnetic interference.
NovaWave also had an MDA Phase I SBIR for developing a system capable of determining coating loss in critical optical components. The company turned this item into its highly successful LossPro™ product. LossPro was designed to be used by technicians to precisely determine reflectance and optical losses in thin-film and optical substrates. LossPro has thus far generated $1 million in sales, and is being used internationally by manufacturers who fabricate lasers for the telecommunications market, as well as the generic neodymium yttrium-aluminum-garnet (Nd-YAG) laser market.
A third SBIR success story is NovaWave’s novel ammonia gas sensor, which can sniff out trouble in industrial, environmental, and general chemical-analysis applications. The ability to determine absolute concentrations of many gas species can also be used for semiconductor gas purity analysis, medical diagnostics, and homeland security applications. Initially developed for ABL with Phase I and II SBIRs, the gas sensor platform can be configured as a dedicated product, according to individual specifications.
NovaWave is also working with the Department of Energy on a miniaturized analyzer for detecting greenhouse gases, and with NASA in developing a compact, cryogen-free mid-wavelength infrared spectrometer for detecting trace gases in planetary atmospheres. The reduced need for coolant and cooler brings down the weight, complexity, and risk of space payloads, thus helping to lower cost.
Other projects in the works include an ultrasensitive, fiber-laser-based explosives detector suitable for passenger and cargo screening. Two Army Phase II SBIRs, initiated in 2005, centered on developing a detector for chemical and biological agents in the field, with detection at the single-molecule/ particle level, for monitoring pathogens in water-supply systems and in the air.
NovaWave has recently expanded its square footage on the strength of its tripled revenues from 2004 to the present, and is looking forward to healthy growth in applications for its core laser and sensor technologies.