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Imaging Fourier transform spectroscopy from a space based platform : the Herschel/SPIRE Fourier transform spectrometerSpencer, Locke Dean, University of Lethbridge. Faculty of Arts and Science January 2009 (has links)
The Herschel Space Observatory (Herschel), a
flagship mission of the European
Space Agency (ESA), is comprised of three cryogenically cooled instruments commissioned
to explore the far-infrared/submillimetre universe. Herschel's remote orbit at the second
Lagrangian point (L2) of the Sun-Earth system, and its cryogenic payload, impose a need
for thorough instrument characterization and rigorous testing as there will be no possibility
for any servicing after launch.
The Spectral and Photometric Imaging Receiver (SPIRE) is one of the instrument
payloads aboard Herschel and consists of a three band imaging photometer and a two band
imaging spectrometer. The imaging spectrometer on SPIRE consists of a Mach-Zehnder
(MZ)-Fourier transform spectrometer (FTS) coupled with bolometric detector arrays to
form an imaging FTS (IFTS). This thesis presents experiments conducted to verify the
performance of an IFTS system from a space based platform, i.e. the use of the SPIRE
IFTS within the Herschel space observatory. Prior to launch, the SPIRE instrument has
undergone a series of performance verification tests conducted at the Rutherford Appleton
Laboratory (RAL) near Oxford, UK. Canada is involved in the SPIRE project through
provision of instrument development hardware and software, mission
flight software, and
support personnel. Through this thesis project I have been stationed at RAL for a period
spanning fifteen months to participate in the development, performance verification, and
characterization of both the SPIRE FTS and photometer instruments.
This thesis discusses Fourier transform spectroscopy and related FTS data process
ing (Chapter 2). Detailed discussions are included on the spectral phase related to the FTS
beamsplitter (Chapter 3), the imaging aspects of the SPIRE IFTS instrument (Chapter 4),
and the noise characteristics of the SPIRE bolometer detector arrays as measured using the
SPIRE IFTS (Chapter 5). This thesis presents results from experiments performed both on
site at the RAL Space Science and Technology Department (SSTD) Assembly Integration
Verification (AIV) instrument test facility as well as from the Astronomical Instrumentation
Group (AIG) research laboratories within the Department of Physics & Astronomy at the
University of Lethbridge. / xxiii, 243 leaves : ill. (some col.) ; 29 cm
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SHIFTS : simulator for the Herschel imaging fourier transform spectrometerLindner, John Vyvyan, University of Lethbridge. Faculty of Arts and Science January 2006 (has links)
The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on the European Space Agency's (ESA's) Herschel Space Observatory (HSO). The medium resolution spectroscopic capabilities of SPIRE are provided by an imaging Fourier transform spectrometer (IFTS). A software simulator of the SPIRE IFTS was written to generate realistic data products, making use of available qualification and test data. We present the design and implementation of the simulator. Component and end-to-end simulations were compared to results from the first SPIRE instrument proto-flight model (PFMI) test campaign conducted at the Rutherford Appleton Laboratory (RAL) in Oxford, England in 2005. Final characterization of the simulator involved the determination of astronomical quantities from the synthetic data products of a simple molecular cloud. / xix, 213 leaves : ill. (some col.) ; 29 cm.
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Spectral characterization of the Herschel SPIRE photometerSpencer, Locke Dean, University of Lethbridge. Faculty of Arts and Science January 2005 (has links)
The European Space Agency's Herschel Space Observatory is comprised of three cryogenically cooled instruments commissioned to explore the far infrared/submillimetre universe. The Spectral and Photometric Imaging REceiver (SPIRE) is one of Herschel's instruments and consists of a three band imaging photometer and a two band imaging spectrometer. Canada is involved in the SPIRE project through provision of instrument development hardware and software, mission flight software, and support personnel. This thesis discusses Fourier transform spectroscopy (FTS) and FTS data processing. A detailed discussion is included on FTS phase correction, with results presented from the optimization of an enhanced Forman phase correction routine developed for this work. This thesis discusses the design, verification, and use of the hardware and software provided by Dr. Naylor's group as it relates to SPIRE verification testing. Results of the photometer characterization are presented. The current status of SPIRE and its future schedule is also discussed. / xvii, 239 leaves : ill. (some col.) ; 28 cm.
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Optical MIMO communication systems under illumination constraintsButala, Pankil Mukund 08 April 2016 (has links)
Technology for wireless information access has enabled innovation of 'smart' portable consumer devices. These have been widely adopted and have become an integral part of our daily lives. They need ubiquitous connectivity to the internet to provide value added services, maximize their functionality and create a smarter world to live in. Cisco's visual networking index currently predicts wireless data consumption to increase by 61% per year. This will put additional stress on the already stressed wireless access network infrastructure creating a phenomenon called 'spectrum crunch'.
At the same time, the solid state devices industry has made remarkable advances in energy efficient light-emitting-diodes (LED). The lighting industry is rapidly adopting LEDs to provide illumination in indoor spaces. Lighting fixtures are positioned to support human activities and thus are well located to act as wireless access points. The visible spectrum (380 nm - 780 nm) is yet unregulated and untapped for wireless access. This provides unique opportunity to upgrade existing lighting infrastructure and create a dense grid of small cells by using this additional 'optical' wireless bandwidth. Under the above model, lighting fixtures will service dual missions of illumination and access points for optical wireless communication (OWC).
This dissertation investigates multiple-input multiple-output (MIMO) optical wireless broadcast system under unique constraints imposed by the optical channel and illumination requirements. Sample indexed spatial orthogonal frequency division multiplexing (SIS-OFDM) and metameric modulation (MM) are proposed to achieve higher spectral efficiency by exploiting dimensions of space and color respectively in addition to time and frequency. SIS-OFDM can provide significant additional spectral efficiency of up to (Nsc/2 - 1) x k bits/sym where Nsc is total number of subcarriers and k is number of bits per underlying spatial modulation symbol. MM always generates the true requested illumination color and has the potential to provide better color rendering by incorporating multiple LEDs. A normalization framework is then developed to analyze performance of optical MIMO imaging systems. Performance improvements of up to 45 dB for optical systems have been achieved by decorrelating spatially separate links by incorporating an imaging receiver. The dissertation also studies the impact of visual perception on performance of color shift keying as specified in IEEE 802.15.7 standard. It shows that non-linearity for a practical system can have a performance penalty of up to 15 dB when compared to the simplified linear system abstraction as proposed in the standard. Luminous-signal-to-noise ratio, a novel metric is introduced to compare performance of optical modulation techniques operating at same illumination intensity. The dissertation then introduces singular value decomposition based OWC system architecture to incorporate illumination constraints independent of communication constraints in a MIMO system. It then studies design paradigm for a multi-colored wavelength division multiplexed indoor OWC system.
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