A -- Developments at NIST

Researchers at the National Institute of Standards and Technology (NIST) are working on the following technologies. For further information, contact: National Institute of Standards and Technology, Office of Technology Partnerships, 100 Bureau Drive, Stop 2200, Gaithersburg, Maryland 20899; Fax: +1 (555) 000-0000. This is not an announcement of a contract action or a grant. NIST DOCKET NUMBER: 01-022PA Title: Miniature Frequency Standard Based On All-Optical Excitation And A Micromachined Containment Vessel Description: A design for a microwave frequency standard has been developed which allows for miniaturization down to length scales of order one micron. The frequency standard is based on all-optical excitation techniques such as coherent population trapping (CPT) and stimulated Raman scattering. It comprises a modulated semiconductor laser that illuminates a collection of quantum absorbers contained in a micro-machined cell. In one manifestation, a photodetector located above the cell measures the optical power transmitted through the quantum absorbers, which changes when the laser modulation frequency corresponds to the absorber's transition frequency. This change in transmitted power can be used to stabilize an external oscillator. In another manifestation, a high-speed photodetector above the cell can detect the original laser field beating with a second field originating in the cell through the process of stimulated Raman scattering (SRS). This beat frequency can in principle be very stable as it is referenced directly to the atomic transition. NIST DOCKET NUMBER: 01-023PA Title: The Tripod Manipulator Description: The Tripod Manipulator is a joystick controlled manipulator capable of maneuvering a wide-range of payloads throughout a wide-range of work volumes. This manipulator is notable for its extremely high payload-to-weight ratio as compared to existing commercial manipulators and for its high work volume-to-size ratio. This invention is available for use without a license. NIST DOCKET NUMBER: 02-006PA Title: Fast Transient Microscale Heating For Chemical And Biochemical Detection Description: A method is described for detection of surfactants, and surface active water-soluble polymers and biopolymers in solutions based on temperature measurements of a rapidly heated thin metallic film that is immersed in the liquid. The metallic film, approximately 100-200 micrometers in length by tens of micrometers in width, is heated by application of a voltage pulse of approximately 10 microseconds or less. The electrical resistance of the thin film is measured during application of the voltage pulse. A temperature versus time transient of the heating of the thin film in the liquid is generated from prior calibration of the resistance-temperature characteristics of the film. The presence of surfactants or biopolymers is detected from changes in the heating transient relative to the transient generated in the pure liquid or solvent. Transients exhibit a monotonically increasing heater temperature followed by an inflection point that signals bubble nucleation on the surface from solution boiling. At longer time oscillations are sometimes observed that presumably result from a cyclic growth/collapse nucleate boiling process. The presence of surface-active agents alters the surface tension of the solutions or surface wettability of the heaters which in turn is manifested by changes in the heating transients. The concentration of surface-active agents can be correlated with changes in the integrated temperature of the heating transient (inversely related to the heat transfer to the liquid), changes in the nucleation temperature, or changes in the oscillatory behavior.