DEVELOPMENTS AT NIST Researchers at the National Institute of Standards and Technology (NIST) are working on the following technologies. For further information, contact the National Institute of Standards and Technology, Office of Technology Partnerships, 100 Bureau Drive, Stop 2200, Gaithersburg, Maryland 20899-2200; Telecopy: 301-869-2751. This is not an announcement of a contract action or a grant. NIST DOCKET NUMBER: 00-005PA2, Title: A Novel Cavity Ringdown Heterodyne Spectroscopy: 1 x 10 minus 10 Sensitivity With Microwatt Light Power, Description: The invention is jointly owned by the U. S. Government, as represented by the Secretary of Commerce, and Colorado University. A novel AC technique in cavity ringdown spectroscopy that permits 1X10 minus 10 absorption sensitivity with microwatt level light power has been developed. Two cavity modes, one probing the empty cavity and the other probing intracavity absorption, are excited simultaneously, but their intensities are temporally out of phase, with one mode decayingand the other rising. Heterodyne detection between the two modes reveals the dynamic time constants associated with the empty cavity and the additional intracavity gas absorption. The method offers a quick comparison between the on-resonance and off-resonance information, a prerequisite to reaching the fundamental shot noise limit. This simple and yet important improvement of cavity ringdown spectroscopy should lead to enhanced performance in a wide range of applications. NIST DOCKET NUMBER: 00-009PA, Title: Method For Fixing The Position of Aligned Devices, Description: To ensure proper operation, components to some devices must be initially aligned and then kept within a small alignment tolerance during their useful life. If the alignment degrades, the device may need to be replaced. To be economically competitive, the method used to fix the position of the aligned devices must be low-cost, simple to use (amenable to high-speed automation), and stable over time. This method described here employs angle brackets to fix the position of prealigned components to a substrate. The brackets can be fastened to the substrate and components by means such as soldering, welding, bonding, crimping, and other attachment technologies. The brackets are able to always conform to both the relative of the substrate in many degrees of freedom. These brackets overcome the common problems associated with current production methods, such as relatively thick solder pads, by being easily automated and by resisting creep over time. NIST DOCKET NUMBER: 00-015, Title: Method For Controlling Depth of Recess Pit Etch in the Fabrication of Carrier Wafers, Description: NIST inventors have earlier described a standard silicon wafer that is micro-machined to serve as a carrier for test-chips that are to be inspected with metrology systems equipped to handle only standard wafers and not individual test chips. That invention is identified by NIST docket number 99-008US. The micro-machining process requires patterned etching through, for example,675 um of silicon so as to leave a recess-pit floor thickness of 50 um. Experience has shown that the desired result usually requires labor-intensive process monitoring. The method described in this invention (NIST Docket Number 00-0015) is an aid to enable stopping the etch automatically at the correct depth. The invention comprises a means to enable the operator to more readily detect when the etch has reached the required depth so as to increase yield and avoid instances of over-etching that leave the recess-pit floor too thin to be usable for the intended purpose. WEB: NIST Contracts Homepage, http://www.nist.gov/admin/od/contract/contract.htm. E-MAIL: NIST Contracts Office, kemswiler@nist.gov. Posted 04/21/00 (W-SN447522).

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