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Miniature Spectrometer for Terahertz Time Domain Spectroscopy


In recent years, Terahertz (THz) time-domain spectroscopy (THz-TDS) systems have shown great potential for use in the classification of unknown substances at standoff distances. Most hazardous materials such as explosives and drugs have well-defined spectral fingerprints in the THz frequency range. These fingerprints are used to convert huge, bulky laboratory setups into smaller, lighter and more user-friendly turn-key systems.

NSF funded IGERT trainee Brian Schulkin and researchers including IGERT faculty Xi-Cheng Zhang at Rensselaer Polytechnic Institute have been working on the design and building of a Miniature THz Pulsed Spectrometer since 2006. After over two year’s worth of research and development, the mini spectrometer (see Fig. 1) has become the shining star on the THz research stage. This unit has been widely used, having been tested on everything from NASA’s space shuttle program to Homeland Security defense projects.

Brian selected a miniature pulsed femtosecond laser in his design. A Fiber laser has also previously been used as the laser source in a portable THz system. This system is currently used at the NASA Marshall Space Flight Center in the non-destructive evaluation department. Brian was the first to build a portable THz system for the Marshall Flight Center. The major problem revealed in this system dealt with the mechanical stability of free optics. This problem was temporarily solved through the introduction of new materials other than aluminum (carbon-fiber honeycomb composite, granite, etc.), the use of CAD (computer aided design) drawing and modeling for more efficient design (no surprises when building), and utilizing innovative opto-mechanics that allow for a beam height of 8 mm for increased mechanical stability. The next stage of improvement is to develop this system using fiber optics to provide a solid-state solution.

Brian Schulkin’s achievements, innovation and inventions made him the recipient of many awards; which in 2007 included: IMRA Fellow; NJIT Outstanding Alumni Award; Rensselaer Founders Award of Excellence; Coherent Laser Co Award of Excellence (most innovative award); Inaugural 1st Lemelson-Rensselaer Student Prize; and SCIENTIFIC AMERICAN 50. In February 2008 MIT Technology Review magazine informed IGERT faculty Xi-Cheng Zhang that Brian Schulkin has been nominated by MIT Technology Review magazine on 2008 TR35 award. TR35 is an award for young innovators under 35. Since 1999, the editors of Technology Review have honored the young innovators whose inventions and research they find most exciting; today that collection is the TR35, a list of technologists and scientists, all under the age of 35. Their work—spanning medicine, computing, communications, electronics, nanotechnology, and more—is changing our world.

Address Goals

Brian’s invention of the compact Terahertz spectrometer will have lasting commercial impact in several important industries. Substantial research over the past five years has demonstrated the utility of THz technology to solve challenging problems in Homeland Security. Within the Pharmaceutical and Biomedical industries, however, the realization of those solutions has been limited by the size, weight, expense and fragility of commercially available THz systems. Brian’s task was to develop a THz system that overcame these obstacles and unlock the potential applications already identified in the field. Brian’s innovative approach combined the integration of materials, optics and electronics expertise to realize a quantum leap in robustness, while reducing the size and weight of the system by an order of magnitude. The result is a product ideal for volume manufacturing, allowing a manufacturer to achieve economies of scale to drive down manufacturing costs. This invention also creates a standard platform that can be applied to these independent market needs. The invention was licensed to Zomega Terahertz Corporation in 2007, and several units have been sold to industrial companies.