A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, July 14, 2015. / Hyperspectral images nd application in many areas of modern society, we use them for land surveying, core sample analysis, in the conservation and forestry industries and many more. A major problem in hyperspectral images is how to deal with noise. Many methods that analyse hyperspectral images either need clean images or accurate estimations of the noise statistics in the images. The goal of this dissertation is to present and compare methods for statistic estimation and noise removal. We use an arti cial hyperspectral image to study some existing methods and develop some new ones based on existing methods, speci cally the BM3D algorithm. We test methods that estimate the level of the noise present in an image, methods that estimate the structure of the noise and methods that remove noise. We analyse all the methods under an additive noise model and consider spectrally correlated and uncorrelated noise. Within our investigations we investigate di erent types of correlation. We will show the strengths that the various methods have and establish a way to approach treating a hyperspectral image with no information beyond the image itself. Using our observations and insights from the experiments on the arti cial data we analyse some radiance data from the AVIRIS instrument. We show that the additive signal independent part of the noise is small but not negligible. We also show some evidence for the structure of the noise in the AVIRIS instrument.

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This study investigated the use of UV-visible spectral imaging for the location and enhancement of substances of forensic interest using targeted approaches based on the spectrum of the substance. Spectral enhancement procedures were developed for blood with and without chemical enhancement, and for latent fingermarks after chemical enhancement. Focus was on substances whose spectrum exhibited a steep change in absorbance or fluorescence over a small wavelength range. Substances with such spectral features were able to be enhanced using arithmetic combinations of two or three spectral images taken at wavelengths near the steep spectral feature. Some enhancement reagents do not react to produce a product with a steep spectral feature suitable for photographic enhancement. In such cases reagents that compliment spectral imaging can be developed. A tridentate ligand for iron(II), BBIDMAPP, which forms a complex with a narrow intense charge-transfer band, was synthesised and was used to visualise muddy shoemarks. UV-visible spectral imaging systems based on a liquid crystal filter or a filter wheel were constructed to facilitate the acquisition of the spectral images and to perform the enhancement operations. A thorough characterisation of the imaging systems determined their limitations and sources of artefacts which could lead to complications in interpreting the enhanced images. The spectral imaging procedure used to visualise blood was incorporated into a near-real-time, hand-held imaging system for the location of blood staining. This prototype imaging system is capable of acquiring two spectral images simultaneously, perform the enhancement procedure, and display the enhanced image within 5 s, which would make it suitable as a non-chemical presumptive screening test for blood at crime scenes.

This study investigated the use of UV-visible spectral imaging for the location and enhancement of substances of forensic interest using targeted approaches based on the spectrum of the substance. Spectral enhancement procedures were developed for blood with and without chemical enhancement, and for latent fingermarks after chemical enhancement. Focus was on substances whose spectrum exhibited a steep change in absorbance or fluorescence over a small wavelength range. Substances with such spectral features were able to be enhanced using arithmetic combinations of two or three spectral images taken at wavelengths near the steep spectral feature. Some enhancement reagents do not react to produce a product with a steep spectral feature suitable for photographic enhancement. In such cases reagents that compliment spectral imaging can be developed. A tridentate ligand for iron(II), BBIDMAPP, which forms a complex with a narrow intense charge-transfer band, was synthesised and was used to visualise muddy shoemarks. UV-visible spectral imaging systems based on a liquid crystal filter or a filter wheel were constructed to facilitate the acquisition of the spectral images and to perform the enhancement operations. A thorough characterisation of the imaging systems determined their limitations and sources of artefacts which could lead to complications in interpreting the enhanced images. The spectral imaging procedure used to visualise blood was incorporated into a near-real-time, hand-held imaging system for the location of blood staining. This prototype imaging system is capable of acquiring two spectral images simultaneously, perform the enhancement procedure, and display the enhanced image within 5 s, which would make it suitable as a non-chemical presumptive screening test for blood at crime scenes.

This study investigated the use of UV-visible spectral imaging for the location and enhancement of substances of forensic interest using targeted approaches based on the spectrum of the substance. Spectral enhancement procedures were developed for blood with and without chemical enhancement, and for latent fingermarks after chemical enhancement. Focus was on substances whose spectrum exhibited a steep change in absorbance or fluorescence over a small wavelength range. Substances with such spectral features were able to be enhanced using arithmetic combinations of two or three spectral images taken at wavelengths near the steep spectral feature. Some enhancement reagents do not react to produce a product with a steep spectral feature suitable for photographic enhancement. In such cases reagents that compliment spectral imaging can be developed. A tridentate ligand for iron(II), BBIDMAPP, which forms a complex with a narrow intense charge-transfer band, was synthesised and was used to visualise muddy shoemarks. UV-visible spectral imaging systems based on a liquid crystal filter or a filter wheel were constructed to facilitate the acquisition of the spectral images and to perform the enhancement operations. A thorough characterisation of the imaging systems determined their limitations and sources of artefacts which could lead to complications in interpreting the enhanced images. The spectral imaging procedure used to visualise blood was incorporated into a near-real-time, hand-held imaging system for the location of blood staining. This prototype imaging system is capable of acquiring two spectral images simultaneously, perform the enhancement procedure, and display the enhanced image within 5 s, which would make it suitable as a non-chemical presumptive screening test for blood at crime scenes.

This study investigated the use of UV-visible spectral imaging for the location and enhancement of substances of forensic interest using targeted approaches based on the spectrum of the substance. Spectral enhancement procedures were developed for blood with and without chemical enhancement, and for latent fingermarks after chemical enhancement. Focus was on substances whose spectrum exhibited a steep change in absorbance or fluorescence over a small wavelength range. Substances with such spectral features were able to be enhanced using arithmetic combinations of two or three spectral images taken at wavelengths near the steep spectral feature. Some enhancement reagents do not react to produce a product with a steep spectral feature suitable for photographic enhancement. In such cases reagents that compliment spectral imaging can be developed. A tridentate ligand for iron(II), BBIDMAPP, which forms a complex with a narrow intense charge-transfer band, was synthesised and was used to visualise muddy shoemarks. UV-visible spectral imaging systems based on a liquid crystal filter or a filter wheel were constructed to facilitate the acquisition of the spectral images and to perform the enhancement operations. A thorough characterisation of the imaging systems determined their limitations and sources of artefacts which could lead to complications in interpreting the enhanced images. The spectral imaging procedure used to visualise blood was incorporated into a near-real-time, hand-held imaging system for the location of blood staining. This prototype imaging system is capable of acquiring two spectral images simultaneously, perform the enhancement procedure, and display the enhanced image within 5 s, which would make it suitable as a non-chemical presumptive screening test for blood at crime scenes.

The main focus of this dissertation is to develop a multispectral imaging system with spectral zooming capability and also successfully demonstrate its promising medical applications through combining this technique with microscope system. The realization of the multispectral imaging method in this dissertation is based on the 4-f spatial filtering principle. When a collimated light is dispersed by the grating, there exists a clear linear distribution spectral line or spectrum at the Fourier plane of the Fourier transform lens group base on the Abbe imaging theory and optics Fourier Transform principle. The optical images, not the collimated light, are applied into this setup and the spectrum distribution still keeps linear relationship with the spatial positions at Fourier plane, even through there exists additional spectral crosstalk or overlap. The spatial filter or dynamic electrical filters used at the Fourier plane will facilitate randomly access the desired spectral waveband and agilely adjust the passband width. It offers the multispectral imaging functionality with spectral zooming capability. The system is flexible and efficiency. A dual-channel spectral imaging system based on the multispectral imaging method and acousto-optical tunable filter (AOTF) is proposed in the dissertation. The multispectral imaging method and the AOTF will form spate imaging channels and the two spectral channels work together to enhance the system efficiency. The AOTF retro reflection design is explored in the dissertation and experimental results demonstrate this design could effectively improve the spectral resolution of the passband. Moreover, a field lens is introduced into the multispectral imaging system to enhance the field of view of the system detection range. The application of field lens also improves the system spectral resolution, image quality and minimizes the system size. This spectral imaging system can be used for many applications. The compact prototype multispectral imaging system has been built and many outdoor remote spectral imaging tests have been performed. The spectral imaging design has also been successfully applied into microscope imaging. The prototype multispectral microscopy system shows excellent capability for normal optical detection of medical specimen and fluorescent emission imaging/diagnosis. Experiment results have demonstrated this design could realize both spectral zoom and optical zoom at the same time. This design facilitates fast spectral waveband adjustment as well as increasing speed, flexibility, and reduced cost.

<p>Thermal radiation, an omnipresent phenomenon characterized by electromagnetic wave emission from objects above absolute zero, has consistently intrigued scientific exploration throughout history and profoundly influences various technological applications. Traditionally, the primary utilization of thermal radiation has been limited to fields such as lighting, cooling, and energy harvesting. However, the true potential of thermal radiation extends far beyond these energy-oriented applications. Every object imprints a unique signature within its emitted thermal radiation. These signatures, distinguished by their wide-ranging spectral and polarimetric characteristics, represent a rich information source about the emitting objects. The goal of this dissertation is to offer novel prospective and platforms to expand our perception and utilization of the spectral and polarimetric attributes of thermal radiation. It seeks to augment the conventional understanding of thermal radiation as merely an energy source, underlining its immense potential as an information carrier.</p> <p>This dissertation explores the spectral and polarimetric features left within the thermal radiation and how these features can be manipulated. The research uncovers that the macroscopic spectral, spatial, and particularly spin properties of thermal radiation are intimately connected to the underlying symmetry of the microscopic emitters within a nanophotonic system. This close relationship between symmetry and thermal radiation introduces a universal strategy to gain thorough control over the spectral-polarimetric properties of thermal radiation. The control of these properties may spur pioneering developments in encoding information within thermal radiation.</p> <p>Furthermore, platforms to decode these spectral and polarimetric properties in thermal radiation are as pivotal as the encoding platforms. These decoding platforms allow us to uncover hidden messages within this invisible light and enable us to push the boundaries of fully passive and physics-aware machine perception. Nevertheless, contemporary methods for spectrum and polarization resolved detection of thermal radiation, especially in imaging form, are cumbersome, lacking robustness, and prohibitively expensive. Hence, this dissertation explores two fundamentally innovative spectral separation schemes: the nonlocal super-dispersion enabled by optically active crystals and the dispersive dichroism in 2D infrared metasurfaces. These methods present compact, cost-effective, and high-performance solutions for spectral-polarimetric thermal imaging, thereby enhancing its efficacy in diverse applications.</p>

No / The purpose of this research was to correlate in vivo spatial and spectral morphologic changes of short- to long-pulse 532 nm Nd:YAG retinal laser lesions using Fourier-domain optical coherence tomography (FD OCT), autofluorescence (AF), fluorescein angiography (FA), and multispectral imaging. Ten eyes with treatment-naive preproliferative or proliferative diabetic retinopathy were studied. A titration grid of laser burns at 20, 100, and 200 milliseconds was applied to the nasal retina and laser fluence titrated to produce four grades of laser lesion visibility: subvisible (SV), barely visible (BV, light-gray), threshold (TH, gray-white), and suprathreshold (ST, white). The AF, FA, FD-OCT, and multispectral imaging were performed 1 week before laser, and 1 hour, 4 weeks, and 3 and 6 months post-laser. Multispectral imaging measured relative tissue oxygen concentration. Laser burn visibility and lesion size increased in a linear relationship according to fixed fluence levels. At fixed pulse durations, there was a semilogarithmic increase in lesion size over 6 months. At 20 milliseconds, all grades of laser lesion were reduced significantly in size after 6 months: SV, 51%; BV, 54%; TH, 49%; and ST, 50% (P < 0.001), with retinal pigment epithelial proliferation and photoreceptor infilling. At 20 milliseconds, there was healing of photoreceptor inner segment/outer segment junction layers compared with 100- and 200-millisecond lesions. Significant increases in mean tissue oxygenation (range, four to six units) within the laser titration area and in oxygen concentration across the laser lesions (P < 0.01) were detected at 6 months. For patients undergoing therapeutic laser, there may be improved tissue oxygenation, higher predictability of burn morphology, and more spatial localization of healing responses of burns at 20 milliseconds compared with longer pulse durations over time / Optimedica Corp., the Manchester Academic Health Sciences Centre, and the NIHR Manchester Biomedical Research Centre. JD was funded by a College of Optometrists PhD Studentship, United Kingdom.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The Defense Evaluation Support Activity (DESA) is an independent Office of the Secretary of Defense (OSD) activity that provides tailored evaluation support to government organizations. DESA provides quick-response support capabilities and performs activities ranging from studies to large-scale field activities that include deployment, instrumentation, site setup, event execution, analysis and report writing. The National Guard Bureau requested DESA's assistance in the development and field testing of the Light Armored Vehicle (LAV) Sensor Suite (LSS). LSS was integrated by DESA to provide a multi-sensor suite that detects and identifies ground targets on foot or in vehicles with minimal operator workload. The LSS was designed primarily for deployment in high density drug trafficking areas along the northern and southern borders using primarily commercial-off-the-shelf and government-off-the-shelf equipment. Field testing of the system prototype in summer of 1995 indicates that the LSS will provide a significant new data collection and transfer capability to the National Guard in control of illegal drug transfer across the U.S. borders.