Browsing by Author "Wysocki, Gerard"
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Item Development of Digital Signal Processor controlled Quantum Cascade Laser based Trace Gas Sensor Technology(2006-08-01) So, Stephen; Wysocki, Gerard; Frantz, Patrick; Tittel, Frank K.; Center for Multimedia Communications (http://cmc.rice.edu/); Digital Signal Processing (http://dsp.rice.edu/)This work reports the design and integration of a custom digital signal processor (DSP) system into a pulsed quantum cascade laser (QCL) based trace gas sensor to improve its portability, robustness and operating performance. Specifically, this work describes the implementation of a custom prototype DSP data acquisition/system controller based on the Texas Instruments TMS320F2812 for embedded control and processing. In addition, the sensor incorporates oversampling by taking advantage of the high speed conversion capabilities of the analog-to-digital converter (ADC) which is embedded in the DSP. A carbon monoxide (CO) sensor employing a thermoelectrically (TE) cooled, pulsed 4.6 µm distributed feedback (DFB) QCL as a mid-infrared radiation source is used to evaluate the performance characteristics of such a DSP controlled spectroscopic gas sensor.Item Fast wavelength tuning techniques for external cavity lasers(2011-01-11) Wysocki, Gerard; Tittel, Frank K.; Rice University; United States Patent and Trademark OfficeAn apparatus comprising a laser source configured to emit a light beam along a first path, an optical beam steering component configured to steer the light beam from the first path to a second path at an angle to the first path, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path, wherein the angle determines an external cavity length. Included is an apparatus comprising a laser source configured to emit a light beam along a first path, a beam steering component configured to redirect the light beam to a second path at an angle to the first path, wherein the optical beam steering component is configured to change the angle at a rate of at least about one Kilohertz, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path.Item Integrated embedded processor based laser spectroscopic sensor(2012-12-18) So, Stephen; Wysocki, Gerard; Frantz, Patrick J.; Tittel, Frank K.; Rice University; United States Patent and Trademark OfficeA novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.Item Integrated embedded processor based laser spectroscopic sensor(2012-01-17) So, Stephen; Wysocki, Gerard; Frantz, Patrick J.; Tittel, Frank K.; Rice University; United States Patent and Trademark OfficeA novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.Item Piezo activated mode tracking system for widely tunable mode-hop-free external cavity mid-IR semiconductor lasers(2010-06-08) Wysocki, Gerard; Tittel, Frank K.; Curl, Robert F.; Rice University; United States Patent and Trademark OfficeA widely tunable, mode-hop-free semiconductor laser operating in the mid-IR comprises a QCL laser chip having an effective QCL cavity length, a diffraction grating defining a grating angle and an external cavity length with respect to said chip, and means for controlling the QCL cavity length, the external cavity length, and the grating angle. The laser of claim 1 wherein said chip may be tuned over a range of frequencies even in the absence of an anti-reflective coating. The diffraction grating is controllably pivotable and translatable relative to said chip and the effective QCL cavity length can be adjusted by varying the injection current to the chip. The laser can be used for high resolution spectroscopic applications and multi species trace-gas detection. Mode-hopping is avoided by controlling the effective QCL cavity length, the external cavity length, and the grating angle so as to replicate a virtual pivot point.Item Quantum Cascade Laser Spectrometer for Trace-Gas Detection of Exhaled Carbonyl Sulfide(2004-05-01) Wysocki, Gerard; So, Stephen; McCurdy, Matthew; Roller, Chad; Weidman, Daniel; Frantz, Patrick; Curl, Robert; Tittel, Frank K.; Center for Multimedia Communications (http://cmc.rice.edu/)Simultaneous concentration measurements of echaled carbonyl sulfide and carbon dioxide were demonstrated using a pulsed quantum cascade laser based gas sensor. This sensor has potential applications in biomedical diagnostics such as in lung transplant rejection.