Browsing by Author "Kosterev, Anatoliy A."

Now showing 1 - 5 of 5
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    Frequency scanning pulsed laser having synchronously set subthreshold current
    (2007-07-24) Kosterev, Anatoliy A.; Tittel, Frank K.; Rice University; United States Patent and Trademark Office
    The present invention provides methods and apparatus for flexible and reproducible control of quantum cascade laser frequency scans having short (nanosecond) pulse excitations. In accordance with a preferred embodiment of the invention, a method of digital frequency control for pulsed quantum cascade lasers includes digitally synthesizing a sub-threshold current, converting the sub-threshold current to analog form, and generating laser pulses. Preferably, the sub-threshold current is synchronized to the laser pulses.
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    Modulation cancellation method in laser spectroscopy
    (2011-08-30) Kosterev, Anatoliy A.; Curl, Robert F.; Rice University; United States Patent and Trademark Office
    Novel methods and laser spectroscopic systems for accurately measuring the concentration of compounds are disclosed herein. The disclosed methods utilize a modulation cancellation technique resulting in a significantly increase in the sensitivity and accuracy of laser spectroscopic measurements. In general, the methods and systems utilize modulation phase-shifting and amplitude attenuation to cancel the signals detected from at least two modulated light beams. Thus, any signal detected will be directly proportional to the concentration measurement.
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    Quartz-enhanced photoacoustic spectroscopy
    (2007-07-17) Kosterev, Anatoliy A.; Rice University; United States Patent and Trademark Office
    Methods and apparatus for detecting photoacoustic signals in fluid media are described. The present invention differs from conventional photoacoustic spectroscopy in that rather than accumulating the absorbed energy in the fluid of a sample cell, the absorbed energy is accumulated in an acoustic detector or sensitive element. In a preferred embodiment, the acoustic detector comprises piezoelectric crystal quartz. The quartz is preferably in the shape of a tuning fork.
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    Resonant optothermoacoustic detection of optical absorption
    (2012-01-24) Kosterev, Anatoliy A.; Bachilo, Sergei M.; Rice University; United States Patent and Trademark Office
    A device comprising an acoustic detector, one or more thermal sensing elements coupled to the acoustic detector, and a light source. A method comprising directing a beam of light at a wavelength at or near one or more thermal sensing elements, wherein the thermal sensing elements are coupled to an acoustic detector, determining a resonance frequency of the acoustic detector, wherein the acoustic detector is coupled to one or more of the thermal sensing elements, and measuring the response of the acoustic detector to detect optical radiation absorption proximate to or at the surface of one or more thermal sensing elements.
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    Selectivity enhancement in photoacoustic gas analysis via phase-sensitive detection at high modulation frequency
    (2010-10-05) Kosterev, Anatoliy A.; Rice University; United States Patent and Trademark Office
    A method for detecting a target fluid in a fluid sample comprising a first fluid and the target fluid using photoacoustic spectroscopy (PAS), comprises a) providing a light source configured to introduce an optical signal having at least one wavelength into the fluid sample; b) modulating the optical signal at a desired modulation frequency such that the optical signal generates an acoustic signal in the fluid sample; c) measuring the acoustic signal in a resonant acoustic detector; and d) using the phase of the acoustic signal to detect the presence of the target fluid.