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dc.contributor.advisorKarunasiri, Gamani
dc.contributor.authorNg, Mun Wai Raymond
dc.dateMar-12
dc.date.accessioned2012-05-14T18:55:59Z
dc.date.available2012-05-14T18:55:59Z
dc.date.issued2012-03
dc.identifier.urihttp://hdl.handle.net/10945/6845
dc.description.abstractVideo rate or real-time imaging in the terahertz (THz) frequency range has become possible in the last few years with the advent of compact and high power THz sources, such as quantum cascade (QC) lasers, and the THz-sensitive vanadium oxide based microbolometer focal plane arrays. A new higher power QCL had been acquired and was characterized using FTIR spectroscopic techniques as part of this thesis. Spectral analysis revealed the center radiation frequency to be about 3.78 THz, which was close to the manufacturers specification. Relative power analysis showed significantly higher magnitude, of at least two orders, than the previous low power QCL. Significant temperature build-up of the cryostat, where the laser was mounted, was noticed in terms of a temperature rise of about 16 Kelvins, but was not detrimental to the laser performance. Active real-time THz imaging was conducted with the laser and a 160 x 120 element microbolometer focal plane array camera, FLIR A20M. The off-axis parabolic (OAP) reflective mirrors were re-configured for the imaging experiment to ensure sufficient THz energy would be focused onto the object. This optical setup could be easily re-configured for either transmission mode, as well as reflective mode imaging experiments. A synchronization circuitry was designed to synchronously modulate the QCL pulses with the focal plane array for differential imaging. This operation would eliminate unwanted signals from the infrared background, obviating the need for dedicated spectral filters that would have significantly attenuated the THz signal as well. Preliminary experiments showed better contrast in the acquired images. Post-processing algorithms such as addition of digital gain, enhanced edges, and integration of multiple images could potentially enhance the quality of the THz images, and extend the research towards reflective and stand-off THz imaging.en_US
dc.description.urihttp://archive.org/details/highpowerquantum109456845
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.titleHigh Power Quantum Cascade Laser for Terahertz Imagingen_US
dc.typeThesisen_US
dc.contributor.secondreaderAlves, Fabio
dc.contributor.departmentElectronic Warfare Systems Engineering
dc.subject.authorTerahertz imagingen_US
dc.subject.authorquantum cascade laseren_US
dc.subject.authormicrobolometeren_US
dc.description.serviceCivilian, DSO National Laboratories, Singaporeen_US
etd.thesisdegree.nameMaster of Science In Electronic Warfare Systems Engineeringen_US
etd.thesisdegree.levelMastersen_US
etd.thesisdegree.disciplineElectronic Warfare Systems Engineeringen_US
etd.thesisdegree.grantorNaval Postgraduate Schoolen_US


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