Browsing by Author "Tittel, Frank"

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    Accurate measurement of nanomechanical motion in a fiber-taper nano-optomechanical system
    (AIP Publishing LLC, 2019) Zheng, Huadan; Qiu, Weiqia; Gu, Xiaohang; Zhang, Yu; Zhu, Wenguo; Huang, Bincheng; Lu, Huihui; Guan, Heyuan; Xiao, Yi; Zhong, Yongchun; Fang, Junbin; Luo, Yunhan; Zhang, Jun; Yu, Jianhui; Tittel, Frank; Chen, Zhe
    The hybrid systems that couple optical and mechanical degrees of freedom in nanoscale devices offer an unprecedented opportunity and development in laboratories worldwide. A nano-optomechanical (NOM) system that converts energy directly/inversely between optics and mechanics opens an approach to control the behavior of light and light-driven mechanics. An accurate measurement of the mechanical motion of a fiber-taper NOM system is a critical challenge. In this work, an optical microscope was used to measure the nanoscale mechanical motion of the fiber taper by introducing white light interference. The resolution of mechanical motion monitoring achieved 0.356 nm with an optomechanical efficiency of >20 nm/μW. This paper describes an approach to characterize NOM transducers between optical and mechanical signals in both classical and quantum fields.
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    Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults
    (IOP Publishing, 2015) Spacek, Lisa A.; Mudalel, Matthew; Tittel, Frank; Risby, Terence H.; Solga, Steven F.
    Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L(-1) (interquartile range (IQR), 3-18) versus 46 μmol L(-1) (IQR, 23-66) for cirrhotic participants. Median breath ammonia was 379 pmol mL(-1) CO2 (IQR, 265-765) for healthy versus 350 pmol mL(-1) CO2 (IQR, 180-1013) for cirrhotic participants. CV was 17  ±  6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia.
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    Mid-IR Spectral Investigation of Normal and Malignant Breast and Cervical Tissue Samples Using a Quantum Cascade Laser-Based Microscope
    (2017-04-21) Haugen, Paul; Drezek, Rebekah; Tittel, Frank
    Mid-infrared (MIR) spectroscopy has been a tool used to identify specific features of normal and malignant tissue samples by utilizing MIR characteristics, specifically in the “fingerprint” region. The fingerprint region is a biologically significant spectral region typically identified between 1500 and 500 cm-1. MIR spectroscopy can be used to study molecular changes and variations occurring in samples, which can then be used to fingerprint specific spectral characteristics and biomarkers in order to categorize the specimens. The most common instruments currently used in this analysis are Fourier transform infrared (FTIR) spectrometers, although properties inherent in these instruments, such as slow data collection time and an inability to specify sample location for the spectral data collection, have placed a ceiling on the clinical practicality of their use for specimen classification and identification. In this thesis, we use a prototype of an infrared hyperspectral imaging microscopy platform based around tunable quantum cascade laser (QCL) technology that has a spectral coverage from 1800-900 cm-1. The quantum cascade lasers are coupled with a series of MIR refractive objectives and an uncooled microbolometer camera. The speed of spectral imaging improves to 30 frames per second, and the high magnification objective has a 1.34 µm pixel resolution with a 0.70 numerical aperture and 4.3 µm spatial resolution. We are able to specify data collection at specific discrete wavelengths as opposed to the full spectrum, which improves the data collection time and de-clutters the data for analysis expediency. Finally, we perform spectral imaging real-time, which aides in selecting precise regions of interest on the target sample. This thesis demonstrates the advantages of exploiting the capabilities of the QCL microscope to advance MIR spectroscopy in the identification of distinguishing traits of normal and malignant breast and cervical tissue samples.
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    A New Phase Shifting Technique for Deep UV Excimer Laser Based Lithography
    (SPIE, 1995-02-01) Bor, Zsolt; Cavallaro, Joseph R.; Erdelyi, Miklos; Kido, Motoi; Sengupta, Chaitali; Smayling, Michael; Szabo, Gabor; Tittel, Frank; Wilson, William; Center for Multimedia Communication
    This paper reports simulation and experimental details of a novel phase shifting technique based o laser interferometry. Phase shifting is one of the most promising techniques for the fabrication of high density DRAM's. In recent years many kinds of phase shifting methods have been proposed to extend the resolution limit and contrast of image patterns. These techniques however, have several problems that result from the phase shift elements on the mask, especially when applied to UV excimer laser illumination. A new technique will be described that is based on a one-layered reticle which is used as both a reflective and transmissive mask, irradiated from both the front and the back sides. A combination of both off-axis illumination, as well as phase shift are used in this method. Both the relative path length of the two beams as well as their amplitude can be manipulated in such a way that near 100% contrast can be achieved in the final image. Experimental as well as simulation data are used to demonstrate this new method.