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Removing Bioactive Contaminants by Use of Atomic Oxygen

Bioactive contaminants are removed without using liquid chemical baths or high temperatures. A method of removing endotoxins and other biologically active organic compounds from the surfaces of solid objects is based on exposure of the objects to monatomic oxygen generated in oxygen plasmas. The mon- atomic oxygen reacts strongly and preferentially with the organic contaminants to form volatile chemical species. The method was developed especially for removing such contaminants as lipopolysaccharides, proteins, lipids, and other biologically active contaminants from surfaces of orthopedic implants prior to sterilization and implantation; if not removed, these con- taminants can contribute to inflammation that sometimes necessitates the surgical removal of the implants.

Posted in: Briefs, TSP, Materials

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Monolithic Diffraction Grating Arrays Enable Wide-Bandwidth Single-Shot Spectrometers

For the last forty years, manufacturing technology for diffraction gratings has not changed significantly. Mechanical ruling and interferometric (holographic) exposure have been the two predominant approaches used to fabricate gratings. Both approaches provide limited freedom in terms of the complexity of grating lines (spacings and curvatures) that can be written.

Posted in: Articles, Features, ptb catchall, Photonics

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InGaAs SWIR Imagers Optimize Semiconductor Inspection

As the volume of consumer electronics increases, semiconductor fabrication plants are manufacturing larger and larger wafers to handle the demand (e.g., 300 mm substrates). The escalating value of these larger wafers is driving the industry to employ more advanced imaging technologies for quality control. Inspecting the raw material substrate for flaws before processing and detecting defects during processing is critical to keeping costs down. New and improved inspection techniques save the semiconductor manufacturing industry hundreds of millions of dollars each year.

Posted in: Application Briefs, Applications, ptb catchall, Photonics

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Electro-Optical Modulator Bias Control Using Bipolar Pulses

Bias is automatically adjusted to maintain maximum extinction during “off” periods. NASA’s Jet Propulsion Laboratory, Pasadena, California An improved method has been devised for controlling the DC bias applied to an electro-optical crystal that is part of a Mach-Zehnder modulator that generates low-duty-cycle optical pulses for a pulse-position modulation (PPM) optical data-communication system. In such a system, it is desirable to minimize the transmission of light during the intervals between pulses, and for this purpose, it is necessary to maximize the extinction ratio of the modulator (the ratio between the power transmitted during an “on” period and the power transmitted during an “off” period). The present method is related to prior dither error feedback methods, but unlike in those methods, there is no need for an auxiliary modulation subsystem to generate a dithering signal. Instead, as described below, dither is effected through alternation of the polarity of the modulation signal.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics

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Fiber-Optic Strain Gauge With High Resolution And Update Rate

Changes in strain are correlated with changes in speckle patterns. Stennis Space Center, Mississippi An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are useful mainly for measuring small strains (including those associated with vibrations) in such structures as rocket test stands, buildings, oilrigs, bridges, and dams. The technology was inspired by the need to measure very small strains on structures supporting liquid oxygen tanks, as a way to measure accurately mass of liquid oxygen during rocket engine testing.

Posted in: Briefs, ptb catchall, Tech Briefs, Photonics

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Product of the Month: Optical Receiver Stress Test Set

Agilent Technologies (Santa Clara, CA) has introduced the N4917A optical receiver stress test set to provide repeatable conformance and characterization test results. The design allows users to accurately characterize and verify standard conformance of receiver optical subassemblies and transceiver modules operating up to 12.5 Gb/s. The test set provides the calibrated injection of optical modulation amplitude (OMA), extinction ratio (ER), and vertical eye closure penalty (VECP) through automation software controls.

Posted in: Products, Products

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Fiber Optical Switches

Laser Components IG (Hudson, NH) has introduced a series of fiber optical switches with core diameters of up to 600 μm. The "mol 1×N" and "mol 2×N" feature switching times of two milliseconds and low signal loss (less than 0.5 dB). The switches are available in various configurations, and come with or without a connector in compact housings, table housings, or 19" insertions.

Posted in: Products, Products

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