Chromatic aberration

The purpose of the following experiments and this conclusive report is to obtain an appreciative understanding of the properties of light and how paraxial rays interact with a variety of optical mediums. The first phenomenon to be observed is reflection from a plane, spherical and parabolic mirror with the objective of measuring angles, focal lengths and the radius of curvatures. Secondly is refraction by biconcave and biconvex lenses with the intention of calculating the optical power of a lens. Finally, Snell’s Law shall be used to measure the refractive index of a glass block. Throughout the experiments, problematic effects associated with such optical mediums known as chromatic and spherical aberration will be observed. From acknowledging and understanding these problems, cameras can be designed and used in ways to improve the image taking capability.

Leucism is an aberration of color that may occur in
different groups of organisms as a consequence of genetic mutations. This phenomenon in bats has been reported in various countries in Latin America, where Colombia is the country with more reports for species in the Phyllostomidae family. In this work, we present the first records of leucism in Artibeus planirostris from department of Cordoba (Colombia), whose specimens have atypical coloration in hair and membranes.

A new type of metasurface lens developed by US researchers is far less susceptible to optical dispersion than previous designs-which means that it can focus a wider range of wavelengths more efficiently. Boubacar Kanté of the University of California, Berkeley and colleagues believe their new lens could find a range applications including hi-tech medical imaging, energy harvesting and virtual reality. [35] Susanne Hellmuth and Olaf Stemmann from the chair of genetics at the University of Bayreuth have now discovered a previously unknown mechanism that regulates the activity of the separase. [34] A team of UNSW scientists at the School of Biotechnology and Biomolecular Sciences led by Professor Andrew Brown have shown how a key enzyme that contributes to cholesterol production can be regulated-and destroyed-using a particular molecule. [33] Synthetic proteins have been created that move in response to their environment in predictable and tunable ways. [32] Bioinspired materials mimic their natural counterparts for characteristic functionality in multidisciplinary applications forming a popular theme in biomaterials development. [31] MIT engineers have designed tiny robots that can help drug-delivery nanoparticles push their way out of the bloodstream and into a tumor or another disease site. [30] Researchers have shown that existing optical fibre technology could be used to produce microscopic 3-D images of tissue inside the body, paving the way towards 3-D optical biopsies. [29] Researchers at MIT, working with surgeons and oncologists at Massachusetts General Hospital (MGH), have now developed a way to improve the accuracy of this surgery, called debulking. [28] Scientists at the University of Bristol have invented a new technology that could lead to the development of a new generation of smart surgical glues and dressings for chronic wounds. [27]

ABSTRACT
1. Chromatic disorders in bats are being reported worldwide at an increasing rate. However, there is widespread misunderstanding and misuse of the associated terminology and concepts in the scientific literature. We conducted an extensive assessment and standardisation of published and unpublished cases of chromatic disorders in bats worldwide.
2. Chromatic disorders have been recorded in at least 609 bats belonging to 115 species and 10 families (after correction of misused terms, 152 cases of albinism, 11 of leucism, 269 of piebaldism, 20 of hypomelanism, three of partial melanism and 94 of melanism; a further 60 records remain unclassified).
3. Of the 354 records in which a location was given, 297 bats were found in closed roost sites, mainly caves, buildings, and mines and galleries, while just three were found roosting externally. This difference could be attributed to the greater monitoring effort employed in underground areas than in forests, and to the greater detectability of bats dwelling in caves and buildings than forest-dwelling species.
4. Although reports of chromatic disorders in bats are reasonably well spread around the globe, there are large areas from which no disorders have ever been reported: the Central Amazon, almost all of Africa, northern Europe, and almost all of Asia and Oceania. This is likely to be attributable to either the disregard for information on chromatic disorders (e.g. Central Amazon) or to the low abundance of occurring species (e.g. northern Europe).
5. In all, 40% of the records of leucism and piebaldism were  misclassified as ‘partial albinism’; leucism was also often used to designate pied aberrations.
6. We propose a standardised classification to distinguish between albinism, leucism, piebaldism, hypomelanism, melanism and partial melanism. Due to frequent confusion, we encourage scientists to follow this classification and we highlight the need to employ comprehensive terminology when describing chromatic disorders in scientific publications.

Eyes with refractive error have reduced visual acuity and are rarely found in the wild. Vertebrate eyes possess a visually guided emmetropisation process within the retina which detects the sign of defocus, and regulates eye growth to align the retina at the focal plane of the eye's optical components to avoid the development of refractive error, such as myopia, an increasing problem in humans [1]. However, the vertebrate retina is complex, and it is not known which of the many classes of retinal neurons are involved [2]. We investigated whether the camera-type eye of an invertebrate, the squid, displays visually guided emmetropisation, despite squid eyes having a simple photoreceptor-only retina [3]. We exploited inherent longitudinal chromatic aberration (LCA) to create disparate focal lengths within squid eyes. We found that squid raised under orange light had proportionately longer eyes and more myopic refractions than those raised under blue light, and when switched between...

ARTICLE INFO ABSTRACT In a digital camera, the causes of color artifacts are due to the characteristics of an image sensor or an optical device. Chromatic aberration is one of the color artifacts. Because chromatic aberration is unpleasant to the eye, users are likely to eliminate or correct the color fringed pixels. At present, most users select the regions which contain the color fringed pixels, and correct them using software such as Adobe® PhotoShop. Other applications such as PTLens® use lookup table of precomputed parameters to reduce the artifacts. This study aims to correct the effects of Chromatic Aberration automatically and overcome the limitations of optics manufacturing technology through the use of Almalance's PhotoAcute Studio, which corrects this aberration automatically, minimizing the circle of confusion, with no need of manual adjustments of any parameters. The study thus concluded that, the Almalence PhotoAcute studio was able to achieve high quality images without any annoying chromatic aberration (red and green fringing) and overcame the limitations of the optics manufacturing technology.

Longitudinal chromatic aberration of the eye (LCA) produces "color fringes" at edges that specify focus. Fincham [(1951) British Journal of Ophthalmology, 35, 381-393] concluded that these chromatic effects were important for accommodation, but most investigators disagree. We monitored accommodation in 25 subjects while they viewed a sinusoidally moving target (1.5-2.5 D at 0.2 Hz) in a Badal optometer. The target was monochromatic (590 nm with 10 nm bandwidth), or white (3000 K) with LCA normal, neutralized or reversed. Sensitivity to the effects of LCA is profound and widespread. Gain decreases substantially and phase-lag increases when LCA is eliminated, and reversing the aberration severely disrupts accommodation. The ordered arrangement of spectral foci produced by LCA seems to be a fundamental aspect of the stimulus for "reflex" accommodation.

The performance of absolute polar duty cycle division multiplexing (AP-DCDM) over wavelength division multiplexing (WDM) system is presented based on the simulation results. The AP-DCDM signal has narrower bandwidth than conventional time division multiplexing (TDM) signal, which makes its implementation in WDM system advantageous. In this paper, characteristics of AP-DCDM and TDM signals in WDM system are compared at the speed of 40 Gbit/s per channel, for the minimum allowed channel spacing and the chromatic dispersion tolerance. The results clearly show that AP-DCDM performs significantly better than TDM. By using AP-DCDM, 1.28 Tbit/s (32 x 40 Gbit/s) was successfully transmitted over 320 km standard single mode fiber. Spectral efficiency of 0.64 b/s/Hz was achieved by using 10 Gbit/s transmitters and receivers without polarization multiplexing.