Low-Energy X-Ray Spectrometer
Summary:
Parallax Research has developed the Low-Energy X-Ray Spectrometer (LEXS), which includes a collimator/focuser to collect a larger angle of diverging x-rays than a conventional spectrometer, resulting in shorter data collection times and better detection sensitivity. Parallax received BMDO SBIR Phase I and II funding for developing collimating optics for x-ray spectroscopy and for developing a spectroscope. The LEXS is available for license to x-ray instrumentation manufacturers or for custom applications.
Technology Description:
Parallax Research, Inc., is using the company's x-ray optics technology to produce more efficient x-ray spectrometers for various analytical instrument systems. The Low-Energy X-Ray Spectrometer (LEXS) uses Parallax's x-ray collimating optics and a simplified spectrometer geometry with a single diffracting turret, which rotates in the parallel beam from the collimator. The x-ray beam is divided into its component wavelengths by the flat crystals on the turret and directed into a fixed large-window proportional counter detector.
Unlike visible light, x-rays are difficult to bend. They either are absorbed or pass through a material. Parallax has developed a collimator/focuser that collects a large angle of diverging x-rays and redirects them into a parallel beam. This collimator collects a much larger fraction of the emitted x-rays than a conventional spectrometer, leading to shorter data collection times and better detection sensitivity for light elements. By incorporating this collimator into the unique LEXS geometry, Parallax is able to produce a wavelength-dispersive spectrometer (WDS) that acts like an energy dispersive spectrometer but has extremely high performance for light-element detection.
Parallax's collimator could improve scanning or transmission electron microscopy (SEM or TEM) analysis by increasing the sensitivity of the detection. SEM and TEM analyze samples by resolving the x-rays emitted (transmitted or reflected) from the sample. (Electron microscopes use a beam of electrons and can make things look a million times bigger. In the transmission electron microscope, the beam passes through the specimen. In the scanning electron microscope, the beam is reflected from the specimen.) Bombarded by an electron beam, the sample emits x-rays of different unique energies depending on the elements of which it is composed. The lower the atomic number of the elements, the lower the intensity of the reflected or transmitted x-ray radiation. So, particularly for low atomic weight elements, it is difficult to resolve the reflected low-energy x-rays into the characteristic peaks of different lines of x-ray energies. The efficiency enhancements of Parallax's collimator are most significant where most needed—in the soft or low-energy x-ray spectral region, where x-ray production efficiencies are relatively low, attenuation (the weakening of a signal as it travels) is high, and detection is difficult.
Instruments for electron microscope imaging and elemental analysis can be either wavelength dispersive or energy dispersive. When used for wavelength-dispersive spectroscopy in SEM and TEM, Parallax's optics will dramatically increase the efficiency of the detection by capturing more of the available spectrum.
The technology would most benefit analysis associated with elements lighter than aluminum. The collimator's enhancement to analytical tools for materials, biologicals, and possibly semiconductors could lead to many new developments in the future.
MDA Origins:
Parallax founder David OHara developed x-ray optics for x-ray lasers for SDIO at Physitron under the SBIR program and with funding from the Defense Nuclear Agency. Parallax's technology builds on that background. Parallax was awarded BMDO SBIR Phase I and II contracts for developing collimating optics for x-ray spectroscopy and for developing a spectroscope.
Spinoff Applications:
To achieve the goal of 90 percent yield, the semiconductor industry must analyze light elements to spot defects on chips. Compared with conventional spectrometers, Parallax's spectrometer collects twenty times more x-rays from a source emitting in all directions, directing the x-rays into a parallel beam. This x-ray collection efficiency can be translated into higher defect sensitivity or into a faster chip-scanning rate for the same defect sensitivity.
The collimator can be used for a variety of materials analysis tasks, such as analyzing ceramic and alloy microstructures and electron microscope imaging of biological materials to analyze their elements. X-rays for lithography need to be parallel, so Parallax's collimator may facilitate making microchips using x-ray lithography. OHara is applying it to x-ray photoelectron spectroscopy to do chemical analysis via x-ray excitation. Chemists could use the process to analyze chemical bonds.
Commercialization:
Parallax has developed two collimating optics for use in x-ray instrumentation. The optics have been integrated into spectrometers (first product, October 1997, second product, February 1998) marketed by NORAN Instruments (Middleton, WI) (formerly Tracor Northern) and are described below:
•The low-energy x-ray collimating optic is a mirror that is incorporated into NORAN's wavelength-dispersive spectrometer (MAXray). As described in the product literature, the MAXRay contains an x-ray focusing optic that “collects and collimates x-rays. The optic, optimized for 100 eV to 1.8 keV detection, produces a parallel beam of x-rays that provide a gain improvement of up to 50 times over WDS analysis. This gain improvement allows analysis at...a new level of x-ray detection never before achieved on an electron microscope.”
•Parallax developed LEXS, which is available for license to x-ray instrumentation OEMs or for custom applications.
Parallax used the equipment from their BMDO SBIR work to develop a technology for making precision molds for injection-molded optics and has patented a process for fabricating the optics economically. The company collaborated on making custom molds for diffraction gratings with a plastic optics manufacturer under a non-disclosure agreement. The company also made a microscopic version of its optics for fiber-optic card connectors for a fiber-optic company.
OHara is working with Martin Richardson at the Center for Research on Electro-Optics and Lasers (CREOL) at the University of Central Florida and another company on x-ray lithography for making microchips.
Under a Florida state defense conversion project, Parallax received $106,000 from Enterprise Florida to combine with the BMDO SBIR money to manufacture the collimator and spectrometer products.
Parallax holds patents on the fabrication of the collimator, the application of the collimator to spectroscopy, the energy dispersive optic, and the spectrometer.
Company Profile:
David OHara incorporated Parallax in March 1996. He is currently the only full-time employee.
Contact Information:
David OHara
Parallax Research, Inc.
PO Box 12212
Tallahassee FL 32317
Tel:850-580-5481 (lab)
904-668-4133 (voice mail)
Fax:850-576-9076
email: dbohara@mindspring.com
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