Total Transmission Of Light Research Articles

Translucency and Strength of Lithium Disilicate for Computer-Aided Design and Manufacturing at Different Thermal Temperatures and Thicknesses: An In Vitro Study.

To manufacture dental restorations composed of lithium disilicate (LD) through the computer-aided design and manufacturing (CAD/CAM) process, thermal refinement is an essential process that can affect the optical and mechanical properties of ceramics. In this study, we aimed to evaluate the translucency and flexural strength of lithium disilicate glass-ceramic for CAD/CAM using different thermal refinement schedules and thicknesses by measuring the total transmission of light through the specimen and calculating the peak load of the specimen until fracture in a piston-on-three-ball test, respectively. The results showed that a lower translucency was exhibited in thicker specimens, and the flexural strength decreased in the order of 1.0, 0.5, and 2.0 mm (p < 0.05). The lithium disilicates thermally refined at a heat of 820 degrees were shown to have the highest biaxial flexural strength (p < 0.05). These findings suggest that it is possible to adjust transparency and strength according to the clinical situation by choosing an appropriate thickness and thermal refinement process.

Transport through Amorphous Photonic Materials with Localization and Bandgap Regimes.

We propose a framework that unifies the description of light transmission through three-dimensional amorphous dielectric materials that exhibit both localization and a photonic bandgap. We argue that direct, coherent reflection near and in the bandgap attenuates the generation of diffuse or localized photons. Using the self-consistent theory of localization and considering the density of states of photons, we can quantitatively describe the total transmission of light for all transport regimes: transparency, light diffusion, localization, and bandgap. Comparison with numerical simulations of light transport through hyperuniform networks supports our theoretical approach.

Modeling quantum light interference on a quantum computer

Modeling of photonic devices traditionally involves solving the equations of light–matter interaction and light propagation. Here, we demonstrate an alternative modeling methodology by reproducing the optical device functionality using a quantum computer. As an illustration, we simulate the quantum interference of light on a thin absorbing film. Such interference can lead to either perfect absorption or total transmission of light through the film, the phenomena attracting attention for data processing applications in classical and quantum information networks. We map the behavior of the photon in the interference experiment to the evolution of a quantum state of transmon, a superconducting charge qubit of the IBM quantum computer. Details of the real optical experiment are flawlessly reproduced on the quantum computer. We argue that the superiority of this methodology shall be apparent in modeling complex multi-photon optical phenomena and devices.

Deterministic and Controllable Photonic Scattering Media via Direct Laser Writing

AbstractPhotonic scattering materials, such as biological tissue and white paper, are made of randomly positioned nanoscale inhomogeneities in refractive index that lead to multiple scattering of light. Typically these materials, both naturally occurring or man‐made, are formed through self assembly of the scattering inhomogeneities, making it extremely challenging to know the exact positions of these inhomogeneities, let alone control those. Here, the nanofabrication of photonic multiple‐scattering media using direct laser writing with a deterministic design is reported on. These deterministic multiple‐scattering media consist of submicron‐thick polymer nanorods that are randomly oriented within a cubic volume. The total transmission of light is studied as a function of the number of rods and of the sample thickness to extract the scattering and transport mean free paths using radiative transfer theory. Such ability to fabricate photonic multiple‐scattering media with deterministic and controllable properties opens up a myriad of opportunities for fundamental studies of light scattering, in particular, in the multiple‐scattering regime and with strong anisotropy and for new applications in solid‐state lighting and photovoltaics.

Measuring distinct regions of grayscale image using pixel values

Grayscale is a series of shades of gray without apparent color. The total absence of transmitted or reflected light, which is the darkest shade, black. The total reflection or transmission of light at all observable wavelengths, which is nothing but lightest possible shade i.e., white. Intermediate shades of gray are characterized by equal brightness levels of the primary colors (red, green and blue) for transmitting light, or equal amounts of the three primary pigments (magenta,cyan, and yellow) for reflected light. This paper focuses mainly on measuring the properties of objects in a grayscale image using Regionprops to calculate the standard Deviation. This is achieved by segmenting a grayscale image to get objects of a binary image. Although, the common problem of including chromatic values to a grayscale image has objective solution,not exact, the present approach tries to provide an approach to help minimize the amount of human labor required for this task. We transfer the source’s whole color “mood” to the target image by matching texture information and luminance between the images rather than selecting RGB colors from a group of colors to an individual color components. We pick out to transfer only chromatic information and retain the target image’s original luminance values. Further, the procedure is improved by permitting the user to match areas of the two images with rectangular swatches. It is essential to develop grayscale image pixel value, resultant to each object in the binary image to inspect the original grayscale image.Based on the original grayscale image pixel values, the pixel value properties in grayscale image are used to do routine calculations.

Enhancing light transmission through a disordered waveguide with inhomogeneous scattering and loss

We enhanced the total transmission of light through a disordered waveguide with spatially inhomogeneous scattering and loss by shaping the incident wavefront of a laser beam. Using an on-chip tapered lead, we were able to access all input modes in the waveguide with a spatial light modulator. The adaptive wavefront shaping resulted in selective coupling of input light to high transmission channels, which bypassed the regions of higher scattering and loss in the waveguide. Spatial inhomogeneity in scattering and loss leads to the modification of the spatial structures of transmission eigenchannels, allowing wavefront shaping to redirect the energy flux to circumvent regions of higher scattering and loss and thereby enhancing the energy transported through the system. This work demonstrates the power of wavefront shaping in coherent control of light transport in inhomogeneous scattering media, which are common in real applications.

Coherent control of total transmission of light through disordered media.

We demonstrate order of magnitude coherent control of total transmission of light through random media by shaping the wave front of the input light. To understand how the finite illumination area on a wide slab affects the maximum values of total transmission, we develop a model based on random matrix theory that reveals the role of long-range correlations. Its predictions are confirmed by numerical simulations and provide physical insight into the experimental results.

Pervasive nanoscale deformation twinning as a catalyst for efficient energy dissipation in a bioceramic armour

Hierarchical composite materials design in biological exoskeletons achieves penetration resistance through a variety of energy-dissipating mechanisms while simultaneously balancing the need for damage localization to avoid compromising the mechanical integrity of the entire structure and to maintain multi-hit capability. Here, we show that the shell of the bivalve Placuna placenta (~99 wt% calcite), which possesses the unique optical property of ~80% total transmission of visible light, simultaneously achieves penetration resistance and deformation localization via increasing energy dissipation density (0.290±0.072 nJ μm(-3)) by approximately an order of magnitude relative to single-crystal geological calcite (0.034±0.013 nJ μm(-3)). P. placenta, which is composed of a layered assembly of elongated diamond-shaped calcite crystals, undergoes pervasive nanoscale deformation twinning (width ~50 nm) surrounding the penetration zone, which catalyses a series of additional inelastic energy dissipating mechanisms such as interfacial and intracrystalline nanocracking, viscoplastic stretching of interfacial organic material, and nanograin formation and reorientation.

Spectral Transmission of the Human Crystalline Lens in Adult and Elderly Persons: Color and Total Transmission of Visible Light

To experimentally measure the spectral transmission of human crystalline lenses belonging to adult and elderly persons, and to determine the color and total transmission of visible light of such crystalline lenses. The spectral transmission curve of 32 human crystalline lenses was measured using a PerkinElmer 800UV/VIS spectrometer. Total transmission of visible light and the chromatic coordinates of these crystalline lenses were determined from these curves for solar illumination. The crystalline lens that filters UV and its transmission in the visible spectrum decreases with age; such a decrease is greater for short wavelengths. The total transmission of visible light decreases, especially after the age of 70 years, and the crystalline color becomes yellower and saturated. The great variability existing in the spectral transmission of the human crystalline lens is lesser between the ages of 40 and 59 years, but greater from the age of 60 and older. The decrement in transmittance between these two age groups varies from 40% for 420 nm to 18% for 580 nm. Nevertheless, it is proven that age is not the only parameter affecting crystalline transmission. In the range of 40 to 59 years, age does not bear an influence on total transmission of light, but from 60 years and older it does. Moreover, the light transmitted decreases with age. This total transmission of light is similar to or lower than the amount that the different intraocular lenses transmit, even with a yellow or orange filter. The color of the human lens becomes yellowish and saturated with age.

Age‐induced change in the color of the human crystalline lens

AbstractPurpose To determine the chromatic coordinates of different human crystalline lenses to analyze the age‐induced change in the color of the crystalline.Methods The spectral transmission of nine human crystalline lenses of different ages were measured by using a Perkin‐Elmer 800 UV/VIS spectrophotometer. Using these data we calculated the chromatic coordinates of each crystalline lens for both solar and incandescent illumination. The study adheres to the tenets of the Declaration of Helsinki for Research Including Human Subjects and was approved by the Institutional Review Board.Results The results show a greater saturation of color with the increase of age. In principle, the change tends towards yellow, although for ages of over 70 years it veers more towards orange colors. All the crystalline lenses were more yellow and saturated under incandescent illumination.Conclusion At the beginning, a young crystalline lens is transparent and its chromatic coordinates practically coincide with those corresponding to solar light. As age increases, the crystalline lens yellows. On the basis of the results obtained, it cannot be claimed that the more yellow a crystalline lens is, the older it is. Our results show that between 40 and 67 years the chromatic coordinates are quite similar, especially under incandescent illumination. However, total transmission of light is more important for vision than the color of the lens and we have found that the age‐induced changes in these two parameters do not always coincide. All this shows that the different factors that influence yellowing of the crystalline lens do not act in the same way on everyone and that crystalline opacification does not depend solely on aging.

The high-transmission photonic crystal heterostructure Y-branch waveguide operating at photonic band region

We design a high-efficiency two-dimensional photonic crystal (PhC) Y-branch waveguide formed as a heterostructure with two different triangular PhCs composed of air holes. At photonic-band frequency regions corresponding to circular equifrequency surfaces, the two PhCs could be taken as effective homogeneous media with effective refractive indices. A triangular coupler composed of the PhC is designed at the input port in order to divide the incident beam into two parts. The two parts finally propagate into different channels. A case demonstrated here shows that the total transmission of light passing through the Y-branch waveguide is about 91.2%. The propagation phenomena can be explained by the mechanism of total internal reflection very well.

Human Lens Transmission of Blue Light: A Comparison of Autofluorescence-Based and Direct Spectral Transmission Determination

Purpose: Direct measurement of the transmission of light through the human lens is not possible in vivo unless invasive techniques are used. In the current study, a reliable in vivo estimate of the transmission of blue light through the lens was assessed by comparing an indirect and noninvasive method based on autofluorescence measurements with a direct method. Methods: Total transmission of blue light was measured in human donor lenses using a direct method applicable only in vitro and compared with transmittance estimates made by an in vivo applicable autofluorescence technique. Results: Human lens transmission of blue light decreases with age by 0.7–0.8% per year at 480 nm. The comparison of methods showed that the autofluorescence-based method correlated significantly with the direct measurements (R = 0.83, p < 0.001) and acceptable agreement between the two methods was found. Discussion: In conclusion, the human lens transmittance of blue light can be measured reliably in vivo. This enables the possibility to correct for retinal light intensities when studying the mechanisms of the circadian rhythm in clinical studies and related disorders and in addition when working with clinical and experimental methods affected by retinal blue light intensities.

Dynamics of temperature dependent optical properties of tissue: dependence on thermally induced alteration.

Thermal damage in heated bovine myocardial tissue is assessed from measured changes in total reflection and transmission of light. Mathematical expressions, based on random walk analysis of light propagation within tissue slabs, are used to relate the diffuse reflection and transmittance to the absorption coefficient, mu a, and effective scattering coefficient, mu's, for samples of myocardial tissue which were subjected to rapid step changes in temperature. Time-dependent changes in mu's, indicate two processes, one with a fast and temperature-dependent rate the other with a slow and apparently temperature-independent rate. For final temperatures above 56.8 degrees C and for the first 500 s after the temperature change, the optical parameters are well fit by exponential forms that exhibit temperature-dependent time constants as predicted by Arrhenius reaction rate theory of thermal damage. The scattering changes are associated with an apparent activation energy, delta E, of 162 kJ/mole and a frequency constant, A, of 3 x 10(23) s-1. This method provides a means for estimating optical coefficients which are needed to assess laser tissue dosimetry.

Resonant rotation of a mirror-reflected wave in a layered structure

Resonant rotation of a mirror-reflected electromagnetic wave through an arbitrary angle by a layered structure with one of the boundary surfaces having a sinusoidal profile is analyzed theoretically. Two angular intervals of effective rotation are shown to exist in the general case. The conditions for structure parameters ensuring the total rotation are obtained. Typical times of relaxation to the steady-state rotation are determined and the case of an incident beam of finite lateral dimensions is considered. The analogy between the total rotation of a mirror-reflected wave and total resonant transmission of light through a metal film is demonstrated.

Localization and Resonance Transmission of Light Waves in a One-Dimensionally Disordered Dielectric. Polarization Effects

Using a diagrammatic self-consistent approach the problem of Anderson localization is treated for photons with different polarizations in a layered random dielectric. The diffusion coefficient and localization length are calculated for photons. Two types of anomalies are found whose manifestation is a divergency of the localization length. One of the anomalies, which originates in the total transmission of light through scatterers, is peculiar to both (s and p) polarizations. Another anomaly associated with the Brewster effect is a feature of p-polarized waves only. [Russian Text Ignored].

Translucency of human dental enamel.

Translucency of human dental enamel was determined by total transmittance of wavelengths from 400 to 700 nm. The transmission coefficient at 525 nm was 0.481 mm-1. Total transmission of light through human dental enamel increased with increasing wavelength. Human tooth enamel is more translucent at higher wavelengths. The translucency of wet human enamel and enamel after dehydration was also measured by total transmittance. The transmission coefficient at 525 nm decreased from 0.482 to 0.313 mm-1 after dehydration and was reversed on rehydration. The decrease in translucency occurred as a result of the replacement of water around the enamel prisms by air during dehydration.

Recording Horizontal Atmospheric Transmission of Light at Night

A photoelectric telephotometer, which measured the illumination produced at a fixed distance from a light source of known candle power, was developed to record directly the total horizontal atmospheric transmission of light at night over a two sea-mile path. The apparatus consisted of a multiplier phototube, a DC amplifier, batteries for operation, and a one-milliampere recorder. It can be set up easily for field use. A 1000-watt projection-type lamp was used as a light source. By means of a standard lamp, the photoelectric telephotometer was calibrated in a laboratory light tunnel to record illumination in sea-mile candles. In the field the photoelectric telephotometer was compared with a visual telephotometer. Transmission measurements showed good agreement between the photoelectric and the visual methods.

The Transmission of Ultraviolet Radiation Through Chinese Window Papers

Both sector photometer and microphotometer analyses were carried out on the Hg spectrum transmitted by papers popularly used as window materials in Chinese homes. The intensity distribution of transmitted radiation, after normal incidence, through samples of twelve different kinds of paper has been studied, and the total transmission calculated for various wavelengths. The total transmission of visible light (4354A) ranges from 38 percent to 72 percent, and of ultraviolet light (2967A) from 16 percent to 41 percent for the papers studied. Oiling the papers with vegetable oil (“tung yu”) increases the transmission by about 50 percent, at the same time narrowing the distribution curve and strengthening the paper against the effects of moisture.