Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 13 of 13 for “"Wavelength Modulation"”.
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Wavelength Modulation and Noise Reduction Using a Minicomputer-Controlledultraviolet - Visible - Near-Infrared Recording Spectrophotometer
Made available in DSpace on 2014-12-10T23:01:59Z (GMT). No. of bitstreams: 1 7500450.pdf: 6453592 bytes, checksum: 3613485c98194a2b43d409e8801a2e4e (MD5) Previous issue date: 1974
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Advances in tunable diode laser spectroscopy for aero engine research
… has to be employed where an additional current modulation is applied to the DFB laser, creating an instantaneous intensity modulated output and a delayed wavelength modulation (WM) output. This technique falls under a metrology branch known as wavelength modulation spectroscopy (WMS).The unknown …
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Hybrid laser with CMOS photonics
… allowing for lasing at virtually arbitrary wavelengths, the possibility of multiwavelength operation with a shared gain medium, elimination of closed-loop control of wavelength tuning, ability to control laser output and wavelength on-chip, and the potential for wavelength modulation using …
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Temperature dependent excitonic effects in silicon
… behaviour. In this project, a wavelength modulation spectroscopy (WMS) instrument is developed for the observation of the exciton-assisted absorption in silicon at various temperatures. The technique enhances weak spectral features that are immersed in a signal background that …
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Near infrared tunable diode laser spectroscopy for aero engine related applications
… hardware in the near-infrared, with output wavelengths that coincide with the absorption spectra of several important gas species of interest, providing a versatile platform for gas analysis instrumentation. In this work the challenges associated with the recovery of gas information from …
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Portable spectroscopy system for ultra-sensitive, real-time measurement of breath ethane
… lead-salt laser and uses a second derivative wavelength modulation detection scheme. A thermally-managed closed-loop refrigeration system has eliminated the need for liquid coolants. The instrument has been field-tested to ensure target performance is sustained in a range of environments, both …
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Near-infrared tunable diode laser absorption spectrometer for trace gas detection
… could be achieved using second harmonic wavelength modulation spectroscopy in the 50-100k Hz region. Instrument sensitivity was enhanced through the use of a Herriott multipass cell. A computer model of the behaviour of a paraxial ray passing through such a cell has been developed, …
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Elastic and inelastic X-ray scattering studies of the low dimensional spin-1/2 quantum magnet TiOCl
… can be reproduced by a one dimensional long-wavelength modulation of a locally dimerized structure.
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Design of an Optical Fiber-Coupled Sensor for Ambient Methane Measurement
… switch between the sweep integration (SI) and wavelength modulation spectroscopy (WMS) detection methods, which inferred the methane volume mixing ratio from an absorption or second-harmonic (2f) feature respectively. Signals controlling the laser injection current were optimized to balance …
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Laser Remote Sensing for Environmental Monitoring
… TDLAS can be conventionally improved by applying modulation; while in the thesis, a different idea is proposed and demonstrated by operating the absorption spectroscopy on a zero light background. Proof-of-principle experiments are performed and considerations regarding real-world applications are …
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Diode Laser Spectroscopy for Measurements of Gas Parameters in Harsh Environments
… scientific as well as industrial applications. Wavelength modulation spectroscopy (WMS) is derivative form of DLS that has been increasingly applied for making self-calibrated measurements in harsh environments due to its improved sensitivity and noise rejection capability compared to direct …
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Activity of methanogenic archaea under simulated Mars analog conditions
… conditions could be proven. Through real-time wavelength modulation spectroscopy measurements the increase in the methane concentration at temperatures down to -5 °C could be detected. The results presented in this thesis contribute to the understanding of the activity potential of methanogenic …
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Design and Characterization of a Current Assisted Photo Mixing Demodulator for Tof Based 3d Cmos Image Sensor
… signal synchronous with the light source modulation signal. CMOS image sensors are capable of integrating the image processing circuitry on the same chip as the light sensitive elements. As compared to other imaging technologies, they have the advantages of lower power consumption and …