There are many ways to calculate the optical forces acting on scattering particles such as Maxwell's stress tensor, Lorentz forces, gradient and scattering forces, Lorenz-Mie formalism, T-matrix. All these approaches use the electromagnetic field and define the amount of linear momentum transferred to the scattering particles. The resulting momentum transferred is proportional to the intensity of the incident fields, however, the momentum of single photons (hbar k) does not naturally appear in these classical expressions. Here, we discuss an alternative Maxwell's stress tensor based formalism that renders the classical electromagnetic field momentum compatible to the quantum mechanical one. This is achieved through the introduction of the quantum conversion which allows the transformation, including units, of the classical fields to wave-function equivalent fields.

The effect of strong localization of electromagnetic field in colloidal photonic crystals (PCs) is considered in present paper. It is shown theoretically that due to lateral modulation of dielectric permittivity of PC the sharp peaks of light’s intensity arise at the band-gap pumping, and light field decays parametrically with depth. The light itself localises at the near-surface volume of the PC and enhances nonlinear light conversion. Theoretical model to explain generic physical picture is presented for two-dimensional PC, and the analytical results are compared with numerical simulations by finite-difference time-domain method for solving the Maxwell’s equations. The fingerprints of enhanced high harmonic generation, which are observed in our experimental studies with globular quartz PCs, justify the main theoretical predictions.

We developed a web-based instructional and research tool that demonstrates the behavior of electromagnetic waves as they propagate through a homogenous medium and through an interface where the second medium can be characterized by an effective complex permittivity and permeability. Either p- or s-polarization wave components can be chosen and the graphical interface includes 2D wave and 3D component representations. The program enables the study of continuity of electromagnetic components, critical angle, Brewster angle, absorption and amplification, behavior of light in sub-unity and negative-index materials, Poynting vector and phase velocity behavior, and positive and negative Goos- Hänchen shifts.

Corona-discharge CD is just the point at which the air breakdown begins to happen. This phenomenon is usually present when high voltage is applied between a needle and a metallic plate. The air molecules begin to ionizate, separation of their positive and negative charges occur and any minimum voltage increment produces a suddenly discharge between the electrodes. At this critical non-equilibrium point, some of the opposite separated charges are recombined and a light violet-blue emission is produced at the tip of the needle. The released energy can cause some kind of chemical transformation on the materials nearby. In this work we reported the composition of this emission captured from tip of the needle. We show the kind of change that this Corona-discharge produced on fabrics of cotton and linen. CD has been considered as one of the most probably effect that generate the image in the so called Turin Shroud. We present some image produced by controlled CD. Some discussion is given.

Photons are being treated as both particles and wave. From the postulates of special relativity and inverse square law, it is equally likely for all other charges surrounding a charge to register information about its presence with certain strength irrespective of the distance of separation. A new method of apparent position of charges is being proposed using which photon is treated as a spherical shell of information with its radius increasing at a rate of speed of light. With this approach, the presence of photon at many places at the same time in a double slit experiment can be explained which can also be extended to matter waves. Based on the mutual separation between all charges and relative speeds, this paper discusses the strength of information i.e energy of photon to be registered at each charge, generation of new information after registering old information and its strength. This paper also discusses the factors resulting in attenuation of information while it is propagating, concern on single photon detectors, applications for renewable energy devices and an insight into quantum mechanical and general relativistic aspects of the new approach.

The study shows that comet moth cocoon fibers exhibit radiative cooing properties with enhanced solar reflectivity and thermal emissivity. Nanostructured voids inside the cocoon fiber enables the cocoons to exhibit strong scattering in the visible and near-infrared. These structures also allow the fibers to exhibit strong shape birefringence and directional reflectivity. Optical waveguiding due to transverse Anderson localization is observed in these natural fibers, where the invariance and large concentration of the voids in the longitudinal direction allow the fiber to confine light in the transverse direction. To mimic the optical effects generated by these natural silk fibers, nanostructured voids are introduced into regenerated silk fibers through wet spinning to enhance reflectivity in the solar spectrum.

Among the natural white colored photonics structures, a bio-system has become of great interest in the field of disordered optical media: the scale of the white beetle Chyphochilus. Despite its low thickness, on average 7 μm, and low refractive index, this beetle exhibits extreme high brightness and unique whiteness. These properties arise from the interaction of light with a complex network of chitin nano filaments embedded in the interior of the scales. As it’s been recently claimed, this could be a consequence of the peculiar morphology of the filaments network that, by means of high filling fraction (0.61) and structural anisotropy, optimizes the multiple scattering of light. We therefore performed a numerical analysis on the structural properties of the chitin network in order to understand their role in the enhancement of the scale scattering intensity. Modeling the filaments as interconnected rod shaped scattering centers, we numerically generated the spatial coordinates of the network components. Controlling the quantities that are claimed to play a fundamental role in the brightness and whiteness properties of the investigated system (filling fraction and average rods orientation, i.e. the anisotropy of the ensemble of scattering centers), we obtained a set of customized random networks. FDTD simulations of light transport have been performed on these systems, observing high reflectance for all the visible frequencies and proving the implemented algorithm to numerically generate the structures is suitable to investigate the dependence of reflectance by anisotropy.

Butterfly wings are live organs embedded with multiple sensory neurons and, in some species, with pheromoneproducing cells. The proper function of butterfly wings demands a suitable temperature range, but the wings can overheat quickly in the sun due to their small thermal capacity. We developed an infrared technique to map butterfly wing temperatures and discovered that despite the wings’ diverse visible colors, regions of wings that contain live cells are the coolest, resulting from the thickness of the wings and scale nanostructures. We also demonstrated that butterflies use behavioral traits to prevent overheating of their wings.

The Islamic world made important discoveries in the field of color science during the medieval era. These included many fundamental ideas on the nature of color. Some of the first hue scales, though partial were developed by these scholars. They also showed that color was a percept and light and color were ontologically distinct. Other contributions by these scholars include descriptions of the color mixtures, color tops, color theory, etc. A few of these contributions will be discussed in this paper with particular attention to the work of Ibn al-Haytham on color.

The teaching of science is a global problem, general studies have been carried out which take into account the effects of color in the educational environment and have had revealing results, however a study has not been made to measure the effects of color in the learning of the sciences, in this specific case of Physics and mathematics. A study of the effects of color on science teaching was conducted, controlling color of various materials such as slides used in class, markers on blackboard, pens, paper sheets, laboratory materials and teacher's clothing color. In this paper we present results of student academic performance, opinion about the subject, development of logical abilities and a comparison with the teaching of science in a free way, that is to say, without control of color. There is also a study of color effects in science education distinguishing between genders and finally comparing the general results in the educational field with those obtained in this work.

Light exerts non-visual effects on a wide range of biological functions and behavior apart from the visual effect. Light can regulate human circadian rhythms, like the secretion of melatonin and cortisol. Light also has influence on body’s physiological parameters, such as blood pressure, heart rate and body temperature. However, human cognitive performance, alertness and mood under different lighting conditions have not been considered thoroughly especially for the complicated visual task like surgical operating procedure. In this paper, an experiment was conducted to investigate the cognition, alertness and mood of healthy participants in a simulated operating room (OR) in the hospital. A LED surgical lamp was used as the light source, which is mixed by three color LEDs (amber, green and blue). The surgical lamp is flexible on both spectrum and intensity. Exposed to different light settings, which are varied from color temperature and luminance, participants were asked to take psychomotor vigilance task (PVT) for alertness measurement, alphabet test for cognitive performance measurement, positive and negative affect schedule (PANAS) for mood measurement. The result showed the participants’ cognitive performance, alertness and mood are related to the color temperature and luminance of the LED light. This research will have a guidance for the surgical lighting environment, which can not only enhance doctors’ efficiency during the operations, but also create a positive and peaceful surgical lighting environment.

A halo is one of the most frequent and impressive optical phenomena easily observable in the sky. It is also one of the natural optical phenomena most often visible through an airplane window. Halos and related phenomena vary from a single spot of light formed by reflection of the sun from the tops of plate-shaped ice crystals to large rings with splashes of colors, caused by a combination of reflection and refraction in ice crystals. Even with extreme heat at the ground, an airplane quickly rises through sufficient altitude to find ice crystals in the clouds, enabling an alert passenger (or pilot) to see ice-crystal optical phenomena. This paper briefly reviews these phenomena with photographs and diagrams. Photographs include commonly seen halos, as well as Bottlinger’s rings, a rare halo that is still not fully explained. Tips are given for enhancing your chances of seeing and understanding halos.

Blue in nature is often associated with beauty. It can be observed all around us, from captivating blue eyes to iridescent blue butterfly wings. While colours in nature are often the result of pigmentation, the majority of natural blue is produced by structural coloration. The colour of the sky, for example, is primarily caused by Rayleigh scattering. In this paper, we examine a single occurrence of blue in nature, specifically the blue appearance of veins near the surface of human skin. The most comprehensive investigation of this coloration to date showed that it arises from a combination of the scattering properties of skin and the absorptance of venous blood. However, that work only considered broad optical properties of these mediums and did not identify the source of the colour. In this paper, we employ in silico experiments, performed using first-principles light interaction models for skin and blood, to investigate the net effect of skin and vein optical properties on their aggregate reflectance across the visible range. We show that the contribution of skin to the distinct appearance of veins primarily results from Rayleigh scattering occurring within the papillary dermis, a sublayer of the skin. The results of this paper, in addition to addressing an old open scientific question, may have practical implications for performing non-invasive measurements of the physiological properties of skin and blood.

Disorder of color vision in humans is the inability to perceive differences between some or all of the colors that are normally perceived by others. Color blindness is usually a birth defect, a genetically determined. For this reason it is much more common in men than women. This paper presents the results of the test FarnsworthD-15 and Lanthony D-15 on a group of volunteers, both adults and children. The study was conducted to compare the results of both tests.

The present work shows the teaching and motivation of University students to think about optics and color effects. The methodology consists of studying the different optical phenomena that occur through the sunsets and then do a correlation of this information with the phenomena and optical effects of the color of class presentations; to determine the motivation and attention of students.

After a few weeks a newborn baby can recognize high contrasts in colors like black and white. They reach full color vision at the age of circa six months. Matching colors is the next milestone. Most children can do it at the age of two. Good color vision is one of the factors which indicate proper development of a child. Presented research shows the correlation between color vision and visual activity. The color vision of a group of children aged 3-8 was examined with saturated Farnsworth D-15. Fransworth test was performed twice - in a standard version and in a magnetic version. The time of completing standard and magnetic tests was measured. Furthermore, parents of subjects answered questions checking the children’s visual activity in 1 - 10 scale. Parents stated whether the child willingly watched books, colored coloring books, put puzzles or liked to play with blocks etc. The Fransworth D-15 test designed for color vision testing can be used to test younger children from the age of 3 years. These are preliminary studies which may be a useful tool for further, more accurate examination on a larger group of subjects.

The color vision has been described as one to be very sensitive to the intake of several chemicals. The present research reviews the published literature that is concerned with color vision impairment due to alcohol. Most of this research considers people under long-term effects of alcohol. However, there is little information about temporary effects of alcohol on color vision. A group of ten volunteers aged 18-40 was studied. During the study levels of alcohol in the body were tested with a standard breathalyzer while color vision were studied using Farnsworth Munsell 100 Hue Color Vision Tests. Keywords: Col

Detection of vision defects of a child without professional knowledge is not easy. Very often, the parents of a small child does not know that their child sees incorrect. Also the youngster, not knowing any other way of seeing, does not know that it is not the best. While the vision of a small child is not yet fully formed, it is worth checking them very early. Defects detected early gives opportunity for the correction of anomalies, which might give the effect of the normal development of vision. According to the indications, the American Optometric Association (AOA) control eye examination should be performed between the ages of 6 months to 3 years, before going to school and then every two years. Members of SPIE Student Chapter, in cooperation with the Visual Optics Group working on the Department of Optics and Photonics (Faculty of Fundamental Problems, Wroclaw University of Science and Technology) for 6 years offer selected kindergartens of Wroclaw participation in project “Screening vision tests in pre-school children”. Depending on the number of involved members of the student chapter and willing to cooperate students of Ophthalmology and Optometry, vision screening test was carried out in up to eight kindergartens every year. The basic purpose of screening vision test is to detect visual defects to start the correction so early in life as possible, while increasing the efficiency of the child's visual potential. The surrounding community is in fact more than enough examples of late diagnose vision problems, which resulted in lack of opportunity or treatment failure