Theory of coherent active convolved illumination for superresolution enhancement

Recently an optical amplification process called the plasmon injection scheme was introduced as an effective solution to overcoming losses in metamaterials. Implementations with near-field imaging applications have indicated substantial performance enhancements even in the presence of noise. This powerful and versatile compensation technique, which has since been renamed to a more generalized active convolved illumination, offers new possibilities of improving the performance of many previously conceived metamaterial-based devices and conventional imaging systems. In this work, we present the first comprehensive mathematical breakdown of active convolved illumination for coherent imaging. Our analysis highlights the distinctive features of active convolved illumination, such as selective spectral amplification and correlations, and provides a rigorous understanding of the loss compensation process. These features are achieved by an auxiliary source coherently superimposed with the object field. The auxiliary source is designed to have three important properties. First, it is correlated with the object field. Second, it is defined over a finite spectral bandwidth. Third, it is amplified over that selected bandwidth. We derive the variance for the image spectrum and show that utilizing the auxiliary source with the above properties can significantly improve the spectral signal-to-noise ratio and resolution limit. Besides enhanced superresolution imaging, the theory can be potentially generalized to the compensation of information or photon loss in a wide variety of coherent and incoherent linear systems including those, for example, in atmospheric imaging, time-domain spectroscopy, ${\cal PT}$ symmetric non-Hermitian photonics, and even quantum computing.Comment: revised, more details and references adde

Plasmonic Superlens Imaging Enhanced by Incoherent Active Convolved Illumination

We introduce a loss compensation method to increase the resolution of near-field imaging with a plasmonic superlens that relies on the convolution of a high spatial frequency passband function with the object. Implementation with incoherent light removes the need for phase information. The method is described theoretically and numerical imaging results with artificial noise are presented, which display enhanced resolution of a few tens of nanometers, or around one-fifteenth of the free space wavelength. A physical implementation of the method is designed and simulated to provide a proof-of-principle, and steps toward experimental implementation are discussed

Superresolution Enhancement with Active Convolved Illumination

The first two decades of the 21st century witnessed the emergence of “metamaterials”. The prospect of unrestricted control over light-matter interactions was a major contributing factor leading to the realization of new technologies and advancement of existing ones. While the field certainly does not lack innovative applications, widespread commercial deployment may still be several decades away. Fabrication of sophisticated 3d micro and nano structures, specially for telecommunications and optical frequencies will require a significant advancement of current technologies. More importantly, the effects of absorption and scattering losses will require a robust solution since this renders any conceivable application of metamaterials impracticable. In this dissertation, a new approach, called Active Convolved Illumination (ACI), is formulated to address the problem of optical losses in metamaterials and plasmonics. An active implementation of ACI’s predecessor the Π scheme formulated to provide compensation for arbitrary spatial frequencies. The concept of “selective amplification” of spatial frequencies is introduced as a method of providing signal amplification with suppressed noise amplification. Pendry’s non-ideal negative index flat lens is intentionally chosen as an example of a stringent and conservative test candidate. A physical implementation of ACI is presented with a plasmonic imaging system. The superlens integrated with a tunable near-field spatial filter designed with a layered metal-dielectric system exhibiting hyperbolic dispersion. A study of the physical generation of the auxiliary shows how selective amplification via convolution, is implemented by a lossy metamaterial functioning as a near-field spatial filter. Additionally the preservation of the mathematical formalism of ACI is presented by integrating the hyperbolic metamaterial with the previously used plasmonic imaging system. A comprehensive mathematical exposition of ACI is developed for coherent light. This provides a rigorous understanding of the role of selective spectral amplification and correlations during the loss compensation process. The spectral variance of noise is derived to prove how an auxiliary source, which is firstly correlated with the object field, secondly is defined over a finite spectral bandwidth and thirdly, provides amplification over the selected bandwidth can significantly improve the spectral signal-to-noise ratio and consequently the resolution limit of a generic lossy plasmonic superlens

Light detection system in higher plant chloroplasts: Pigment mediated or overall photon flux density related

Plants adapt to short term changes in irradiance and quality of the light environment by modulating the structure of the thylakoid membranes to make the best use of the available light energy. Shade-acclimated chloroplasts develop more thylakoid surface area as compared to those growing in full sunlight. Conversion of sun-type chloroplasts to shade-types and vice versa on the basis of total thylakoid membrane surface area can occur quickly. However, the response mechanism of chloroplasts to changes in light levels is yet to be understood. This short term light detection mechanism may be mediated by a pigment system other than photosynthetic pigments or it may be regulated by change in overall photon flux density. In order to verify the light detection mechanism, short term shade-acclimated sunflower chloroplasts were exposed for 4h to low irradiance white light supplemented with one part of the visible spectrum (blue, red, or yellow-green) enhanced up to sun irradiance. The main purpose of the treatment was to induce sun response in shade-acclimated chloroplasts. At the end the treatment period, leaf samples were taken for stereological analysis. Percent volume of chloroplasts and starch grains, actual volumes of palisade cells, chloroplasts, starch, and vacuoles, surface to volume ratio and actual surface area of stromal and granal thylakoid membranes were compared between control and treatment groups. The blue and yellow-green light treatment showed the most reduction in granal thylakoid surface area among the three treatment groups. The stromal thylakoid surface area, actual volume of chloroplasts, starch grains, palisade cells and vacuoles apparently did not respond to the treatment. The photosynthetic rate, relative quantum efficiency, and chlorophyll content did not change in response to short term change in light quality. The stereological data suggested that the light detection system in higher plant chloroplasts is probably regulated by a pigment system and the overall photon flux density incident on the chloroplasts is also critical. The presence of a different pigment system other than the photosynthetic pigments is yet to be established

Hyperbolic metamaterial as a tunable near-field spatial filter for the implementation of the active plasmon injection loss compensation scheme

We present how to physically realize the auxiliary source described in the recently introduced active plasmon injection loss compensation scheme for enhanced near-field superlensing. Particularly, we show that the characteristics of the auxiliary source described in the active plasmon injection scheme including tunable narrow-band and selective amplification via convolution can be realized by using a hyperbolic metamaterial functioning as a near-field spatial filter. Besides loss compensation, the proposed near-field spatial filter can be useful for real-time high resolution edge detection.Comment: 8 pages, 8 figure

Active plasmon injection scheme for subdiffraction imaging with imperfect negative index flat lens

We present an active physical implementation of the recently introduced plasmon injection loss compensation scheme for Pendry's non-ideal negative index flat lens in the presence of realistic material losses and signal-dependent noise. In this active implementation, we propose to use a physically convolved external auxiliary source for signal amplification and suppression of the noise in the imaging system. In comparison with the previous passive implementations of the plasmon injection scheme for sub-diffraction limited imaging, where an inverse filter post-processing is used, the active implementation proposed here allows for deeper subwavelength imaging far beyond the passive post-processing scheme by extending the loss compensation to even higher spatial frequencies.Comment: 13 pages, 15 figure

Chilling photoinhibition in Zea mays L and Zea diploperennis Iltis, Doebely and Guzman: The role of oxygen and antioxidants

Light absorbed by photosynthetic pigments must be distributed either for chemical work, reemitted as fluorescence or safely dissipated as heat. Adverse environmental conditions reduce the dissipation capacity of plants and the excess energy leads to damage to the photosynthetic mechanism, termed photoinhibition. Low, non-freezing temperatures cause such photoinhibition, especially in tropical plants grown in the temperate zone. This damage occurs in the photosystem II and is triggered by highly reactive radicals or reactive forms of dioxygen. Numerous studies point to the involvement of oxygen and antioxidant enzymes and substrates in amelioration of these damages. In C\sb3 plants, dioxygen is thought to offer some protection against photoinhibition by functioning as energy sink in the process of photorespiration and Mehler reaction. In C\sb4 plants this has not been previously investigated. The goal of this research was to investigate the role of oxygen and antioxidants in low temperature photoinhibition by comparing two C\sb4 plants: one chilling sensitive corn (Zea mays) and the other its chilling-tolerant relative Z. diploperennis. Attached leaves of these plants were exposed to chilling (5\sp\circC) and ambient (25\sp\circC) temperatures at different concentrations of oxygen and either darkness or varying light intensities, and the extent of photoinhibition and concentration of antioxidants were then measured. The rates of recovery under non-stressful conditions were also monitored. Our results show that oxygen imparted a significant protection to corn, but not Z. diploperennis, at low temperature. Nevertheless, Z. diploperennis sustained less photoinhibitory damage than corn. Photoinhibition in corn was accompanied by lower antioxidant concentrations. Both photosynthesis and antioxidants recovered by 2 days, suggesting that slow recycling of the latter induced photoinhibition at low temperature and retarded recovery. Maximum oxidation of the antioxidants took place in the presence of high light and low temperature. Chilling induced photoinhibition also required the presence of light

Enhanced superlens imaging with loss-compensating hyperbolic near-field spatial filter

Recently a coherent optical process called plasmon injection ($\Pi$) scheme, which employs an auxiliary source, has been introduced as a new technique to compensate losses in metamaterials. In this work, a physical implementation of the $\Pi$ scheme on a thin silver film is proposed for enhanced superlens imaging. The efficacy of the scheme is illustrated by enhancing near-field imaging deeper beyond the diffraction limit in the presence of absorption losses and noise. The auxiliary source is constructed by a high-intensity illumination of the superlens integrated with a near-field spatial filter. The integrated system enables reconstruction of an object previously unresolvable with the superlens alone. This work elevates the viability of the $\Pi$ scheme as a strong candidate for loss compensation in near-field imaging systems without requiring non-linear effects or gain medium.Comment: 5 pages, 5 figure

Relations of Cercospora beticola with Host Plants and Fungal Antagonists

Cerco pora leaf pot (CLS) cau ed by Cercospora beticola Sacc., is sti ll considered to be the mo t important foliar di ease of ugar beel. The di ea e ha been reported wherever ugar beet i grO\\ n (Bieiholder and Weltzien 1972). Since the di ease wa fir t identified. management of CLS of ugar beet has been an ongoing mi ion of plant pathologists. Toda}. everal trategie are available and applied either s ingly or in combination to manage the di ea e. The e management trategie , which were ummarized by Windels et al. (1998), include cultural practice uch a deep tillage, rotation with non-host crops and identification and elimination of econdary weed host . Other include breeding and use of re i.tant cultivars and application of fungicide. The u e of re i tant sugar beet cultivars has long been an integral pan of CLS management; however, problems associated with selection of re i tant cuhivars again t CLS are wel l documented and were recently reviewed by Weiland and Koch (2004). According to the author , resistance to CLS in sugar beet has been de cribed as quantitatively in herited and rate limiting with respect to disease development (Smith and Gaskill 1970, Ro i et a l. 1999). Although resistant cultivars have proven effective in both North America and Europe, they nonetheless exhibit low heritability (Smith and Ruppel 1974), and cultivar bred for Cercospora resistance can still exhibit leaf pots if climatic condition favorable for the disease occur

Controlled Assembly of Rodlike Viruses with Polymers

A practical method to assemble rodlike tobacco mosaic virus and bacteriophage M13 with polymers was developed, which afforded a 3D core–shell composite with morphological control