NASA SBIR 2004 Solicitation


SUBTOPIC TITLE:Sensors and Detectors for Astrophysics
PROPOSAL TITLE:Metal Mesh Filters for Terahertz Receivers

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Virginia Diodes, Inc.
979 Second Street SE, Suite 309
Charlottesville ,VA 22902 - 6172
(434) 297 - 3257

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Jeffrey L. Hesler
979 Second Street SE, Suite 309
Charlottesville , VA  22902 -6172
(434) 297 - 3257

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
The technical objective of this SBIR program is to develop and demonstrate metal mesh filters for use in NASA's low noise receivers for terahertz astronomy and atmospheric studies. Metal mesh filters, based on a free-standing sheet of metal with a periodic area of apertures, have been used for many years. However, they have proven to be extremely difficult and costly to fabricate and are not presently available over a large part of the terahertz frequency band (100 GHz through 10 THz). Also, the terahertz filters that are available from commercial suppliers tend to have unacceptable loss in the pass-band (20% or more) and often cost over one thousand dollars per filter. Through this program VDI is developing new fabrication processes and mesh designs that will improve performance and greatly reduce costs. Successful completion of this program will make the filters available for NASA's terahertz missions, facilitate the development of improved terahertz detectors (by facilitating bolometer calibration and testing) and also make the filters commercially available for the greater range of terahertz applications that are now emerging, such as imaging systems and spectrometers.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
The new filters will facilitate the development of extremely sensitive direct detector for terahertz applications. For example, JPL requires cooled bandpass filters to prevent saturation of new detectors by stray radiation and to reduce background noise. Astronomical researchers at JPL are developing a wide array of cryogenic detectors for the 1- 10 THz frequency band. Thus, the filters should be made available for each of the frequencies at which such detectors will be used for astronomical observations. A second important application for these filters is in calibrating receivers. For example heterodyne receivers based on hot electron bolometric (HEB) mixers have recently been found to be susceptible to a direct detection heating effect caused by background radiation. Even though astronomical receivers will not be affected by this problem once they are exposed only to the cold sky, this problem can prevent the accurate calibration of the mixers in the laboratory. Cooled bandpass filters are required to alleviate this problem.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Scientific applications of terahertz filters include chemical spectroscopy, plasma diagnostics, biomaterial analysis, electron spin resonance, and diagnostic instruments for particle accelerators. Military applications include compact range radars, covert communications systems, imaging systems, and chemical, explosive and bioagent scanners. Potential large-scale commercial applications of the proposed terahertz filters include portal security imagers and scanners, medical diagnostics for clinical use, last-mile data links, and industrial process control. As terahertz scientists at NASA and elsewhere strive to create more advanced and elaborate terahertz systems, they will benefit from a wider array of fundamental system components, such as those that are available at microwave frequencies. Examples include circulators, isolator, attenuators, rapid switches and frequency filters. The filters being developing in this program represent one further step in the development of a mature terahertz technology base.

Form Printed on 08-01-05 13:52