Visible Light Waves Research Articles

Detection and Measurement of magnetic data for short length wireless communication using FT-IR

Infrared (IR) radiation is a type of electromagnetic radiation. Infrared “light” has a longer wavelength than visible light. Red light has a longer wavelength than other colors of light, and infrared has even longer waves than red does; so infrared is sort of “redder-than-red” light or “beyond red” light. Infrared radiation lies between visible light and radio waves on the electromagnetic spectrum. In this paper, the infrared radiation is used for detecting the magnetic data for high speedy short range wireless communication. But infrared radiation may use in various way. This paper contains the performance of the FT-IR technique that is for multiplexing the transmissions of different users are viewed at the same time.

A facile route to prepare ZnO super-hydrophobic surface with hierarchical structure

Zn oxide film with the special hierarchical structure, consisting of microspheres and nano-nets, has been successfully fabricated by a two-step solution approach on a sapphire substrate. The surface chemistry and morphological features were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). X-ray diffraction pattern (XRD) shows that all diffraction peaks can be indexed to those of the hexagonal wurtzite phase of Zn oxide and no other phases were detected. Transmittance measurements show that the optical transmittance of the sample synthesized at 720 °C on the sapphire substrate is about 73% in the visible light wave band. The water repelling characteristics of the film were measured by the snapshots with a Hitachi camera, and the measurement shows the water has a contact angle (CA) of about 151.3° as well as a small sliding angle (SA) of about 6°. The above measurements indicate that the Zn oxide film has the super-hydrophobic property.

Effect of Mild Visible Light on Rapid Aqueous RAFT Polymerization of Water-Soluble Acrylic Monomers at Ambient Temperature: Initiation and Activation

Upon irradiation with mild visible light using a S-1-ethyl-S′-(α,α′-dimethyl-α′′-acetic acid) trithiocarbonate (EDMAT) and a (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) photoinitiator, water-soluble acrylic monomers undergo a rapid and well-controlled RAFT polymerization directly in acidic aqueous solution at 25 °C. The effect of visible light on this aqueous RAFT polymerization was investigated by employing a periodic light-on−off process. The results demonstrated that EDMAT was stable in acidic aqueous solution but liable to hydrolysis in alkali solution; its absorption covers a wide visible light wave range of 388−520 nm. This led to a rapid and well-controlled RAFT polymerization of acrylic monomers in acidic aqueous solution at 25 °C simply upon irradiation with mild visible light. The kinetic character of RAFT polymerization at 7 °C was quite similar to that at 25 °C, which proceeded rapidly and kept living behavior, implying the negligible thermoactivating effect of this aqueous RAFT polymerization. The trithiocarbonate moieties and monomer units did not hydrolyze in such an acidic aqueous solution over the short duration of RAFT polymerization. A periodic light-on−off process leads to a corresponding repeatable periodic polymerization-on−off process. The essentially polymerization-standstill state in the light-off period indicates the negligible concentration of active radicals and the significant slow intermediate fragmentation reaction. Further turning on this visible light leads to another rapid polymerization process with the same kinetic character as that observed in the former light-on process, suggesting that the fragmentation of intermediate radicals in this aqueous RAFT polymerization was significantly activated by this visible light.

Color Switchable Goggle Lens Based on Electrochromic Polymer Devices

AbstractWe have developed a set of new electrochromic devices (ECDs) for special application goggles, whose color can be switched between transparent and a specific color mode, i.e. blue (B). This paper will discuss the design, film deposition, device assembly and characterizations of the color switchable lens. The ECD is composed of a layer of thin film conducting polymer poly (3,4-(2,2-dimethylpropylenedioxy)thiophene) (PProDOT-Me2), a layer of thin film inorganic oxide V2O5-TiO2, and a layer of ionic conductive electrolyte. The thin films are electrochemically deposited on ITO coated flexible plastic substrate. The whole device is packaged with an UV cured flexible film sealant. The goggle lens exhibit tuneable shade in visible light wave length (380-800nm), with a maximum contrast ratio at 580nm. Meanwhile, other unique properties include fast switching speed, low driving voltage, memory function (no power needed after switching, bistable), great durability, high flexibility, light weight, and inexpensiveness.

The promise of plasmonics

Light is a wonderful medium for carrying information. Optical fibers now span the globe, guiding light signals that convey voluminous streams of voice communications and vast amounts of data. This gargantuan capacity has led some researchers to prophesy that photonic devices--which channel and manipulate visible light and other electromagnetic waves--could someday replace electronic circuits in microprocessors and other computer chips. Unfortunately, the size and performance of photonic devices are constrained by the diffraction limit; because of interference between closely spaced light waves, the width of an optical fiber carrying them must be at least half the light's wavelength inside the material. For chip-based optical signals, which will most likely employ near-infrared wavelengths of about 1,500 nanometers (billionths of a meter), the minimum width is much larger than the smallest electronic devices currently in use; some transistors in silicon integrated circuits, for instance, have features smaller than 100 nanometers.

Squeezing Visible Light Waves into a 3-nm-Thick and 55-nm-Long Plasmon Cavity

We demonstrate controlled squeezing of visible light waves into nanometer-sized optical cavities. The light is perpendicularly confined in a few-nanometer-thick SiO2 film sandwiched between Au claddings in the form of surface plasmon polaritons and exhibits Fabry-Perot resonances in a longitudinal direction. As the thickness of the dielectric core is reduced, the plasmon wavelength becomes shorter; then a smaller cavity is realized. A dispersion relation down to a surface plasmon wavelength of 51 nm for a red light, which is less than 8% of the free-space wavelength, was experimentally observed. Any obvious breakdowns of the macroscopic electromagnetics based on continuous dielectric media were not disclosed for 3-nm-thick cores.

Licht-/Laser-/PDT-Therapie bei Akne

In recent years, a number of studies have evaluated the treatment of acne using electromagnetic waves, such as lasers, photodynamic therapy, visible light or radio waves. While the efficacy of laser treatment is still uncertain, photodynamic therapy shows promising results, but with marked side-effects, as destruction of sebaceous glands. Treatment with blue light (405-420 nm wavelength) also appears effective and can be regarded as an treatment option for inflammatory acne.

Sub-femtosecond X-ray pulse generation and measurement

We report the generation and measurement of isolated soft-X-ray pulses (λX= 14 nm) with a duration of τX=650±150 attoseconds (as) by using few-cycle intense visible/near-infrared (λ0= 750 nm) laser pulses. For the temporal characterization of the X-ray pulses, a cross-correlation technique relying on laser field assisted X-ray photoemission from krypton atoms was employed. The experimental results bear direct evidence of the X-ray pulse being synchronized to the field oscillations of the visible-light pulse with attosecond precision and of bound–free electronic transitions from the 4p state of krypton responding to 90-eV excitation on an attosecond time scale. As a first demonstration of attosecond metrology, the synchronized single sub-fs X-ray pulses were used for tracing the electric field oscillations in a visible-light wave with a resolution of better than 150 as.

Long Afterglows Reveal the Secrets of Distant Fireballs

GAMMA-RAY BURSTSHUNTSVILLE, ALABAMA-- The mysterious cosmic blasts that were the focus of the Fourth Huntsville Gamma-Ray Burst Symposium held here last week are followed by in progressively longer, less energetic wavelengths: x-rays, visible light, and radio waves. In the last few months, clues ranging from the rate at which the afterglows fade to the twinkling of the radio signal have supported the idea that GRBs emerge from shocks within gigantic fireballs billions of light-years from Earth.

Calculation of PSDF of scintillation for 7 μm band TDL beam around water vapour line

We derive the temporal PSDFs theoretically by combining Filho's temporal PSDF and parameters of the absorption line stated in the optical line parameter compilation, and explain some interesting phenomena of the experimental temporal PSDFs by using the derived theoretical temporal PSDF, especially enhancement in the lower frequency region. The theoretical PSDFs tell us that the increasing of the absorption causes the lower corner frequency to shift to the higher frequency. Besides, the magnitude shifting of the lower corner frequency depends on the value of the absorption coefficient as well as the concentration of the absorbing medium. On the other hand, under the same atmospheric conditions, the profiles of the theoretical PSDFs for different wavelengths overlap each other in the higher frequency region, and the higher corner frequency has no relationship to the absorption. We show that the absorption affects the lower frequency region of the PSDFs of the infrared light, while the higher frequency regions of the PSDFs are affected by the refraction of the light like visible light waves.

ON‐LINE COLOUR MEASUREMENT

Colour is not a property which is a physical part of things we see, it is simply the effect of visible light waves bouncing off or passing through the numerous objects in its path. The colour of an object is determined by several things, the characteristics of the light source, the way the object reflects, absorbs or transmits the light waves striking it. Sometimes, however, the effect of surroundings on the eye and mind and the physical condition of the observer can affect the perception of colour. Hence the eye is not always the best device to use for controlling colour in industry, where consistency of colour is all important.

Comparison of simultaneous atmospheric attenuation measurements at visible light, mid-infra-red (3–5μm) and millimetre waves (94GHz)

In this paper we give a review of measurements through the atmosphere of 94 GHz attenuation, mid-infra-red (3–μm) and visible wave transmittances. The relationships between these quantities are given as a function of meteorological parameters. In rainshowers the theoretical predictions, based on Mie scattering theory, are in good agreement with the experimental results. During these showers the excess attenuation due to rain is the same for infra-red and visible light. The relationship between infra-red and 94 GHz attenuation depends on the type of shower. Almost the same results are found in snow-and wet snow-showers, except that 94 GHz waves are less affected by snow than infra-red waves and visible light. (Snow: not melting, and air temperature between 0 and 2°C; wet snow: melting snow). During fog, visible light and infra-red are seriously affected, whereas 94 GHz attenuation has been increased only slightly.

Human exposure to nonionizing radiant energy—Potential hazards and safety standards

During the last quarter century there has been a marked development and increased utilization of equipment and devices for military, industrial, consumer-use, entertainment, and medical applications that emit a large variety of nonionizing radiant energies. These include ultraviolet, infrared, visible light, microwaves, and radio-frequency waves, which are all classified as electromagnetic waves. Many of the electro-magnetic waves at certain frequencies, power levels, and exposure durations can produce biological effects or injury depending on multiple physical and biological variables. Although equipment which utilizes or emits electromagnetic waves provides immeasurable benefits to mankind, it may also create potential hazards to the individual through uncontrolled and excessive radiation emissions. Consequently, questions are being raised such as: 1) How serious are these problems, what are their dimensions, and what acute and/or chronic effects on the human body may be involved? 2) How adequate is our present knowledge about personnel hazards of these radiation types? 3) How can exposure be reduced? 4) How can better regulation be obtained to reduce exposure? This paper reviews the pathophysiology of exposure to ultraviolet, infrared, coherent electromagnetic radiation (laser), microwaves, and radio-frequency radiation, and the protection guides which have been established for these energies. It is also pointed out that there is a need to set limits on the amount of exposure individuals can accept with safety; setting standards, however, is a very complicated process. The objectives of protection are to prevent acute effects and to limit the risks of late effects. The second objective, namely, to limit the risk of possible late effects, becomes difficult. Protection standards are the results of empirical approaches to various problems reflecting current qualitative and quantitative knowledge. A numerical value for a standard of implies a knowledge of the produced at a given level of stress, and that both and stress are measurable. One problem is the definition of what an effect is and whether it can ultimately be shown to modify man's way of life or that of his offspring. If there were a clear-cut relationship between exposure level and pathophysiologic effect, the problem of setting standards would be greatly simplified. Not only are there numerous variables to be considered, but it is often difficult or impossible to obtain the necessary data to draw valid conclusions concerning effects of exposure to various radiant energies. It is important to maintain a proper perspective, and assess realistically the biomedical effects of these radiant energies so that the worker or general public will not be unduly exposed nor will research, development, and beneficial utilization of these energies be hampered or restricted by an undue concern for effects which may be nonexistent or minimal in comparison to other environmental hazards. There is a need for scientific competence--research aimed at creating credible knowledge and data which can stand against the pressure of legal challenge as well as the understandable bias of special interest groups.

NEW ASPECTS OF THE OPTICAL STUDY OF LAYER SILICATES

SUMMARYThe structure of multilayer polytype modifications of layer silicates may be regarded as the result of a combination of regularly oriented single layers. Accordingly, the optical constants of a single layer (of a monolayer polytype modification) may be used for the calculation of optical constants of any other multilayer polytype modification of a given type of layers.The formulas connecting the constants of a polytype modification of layer silicates have enabled the establishment of the main parameters (Ng, Nm, Np, 2V) of the muscovites 1M and 2M2 according to the known optical constants of the muscovite 2M1, and the computation of the new constants of kaolinite and nacrite based on the known parameters of dickite. The optical constants established theoretically were confirmed by direct measurements for muscovite 1M, muscovite 2M2 (gämbelite) and kaolinite. The optically positive character of kaolinite with +2V = 25° has been established.The assumption of the optical mixibility of finely dispersed polyminerallic media, in which the dimensions of monotype crystals are smaller than the visible light waves, made it possible to determine the quantitative relations of clay minerals in the mixtures based on optical constants of oriented aggregates.

Seeing in the Ultra-Violet

According to different authors1, 2, under appropriate conditions seeing is possible in the ultra-violet down to a wave-length as small as 3100 A. This fact has been confirmed on 21 persons (age 25–50 years) using as light sources discharge tubes containing (1) high-pressure mercury, (2) low-pressure cadmium and zinc (both in neon). The tubes were of quartz, 15 mm. × 120 mm. Visible light and short waves (<2700) were cut out by a red purple corex filter. Using one or more filters (each 5 mm.) the intensity of the Hg line 4047 relative to 3650 and 3130 could be varied within wide limits. A small monochromator (without second slit) was used to separate the different wave-lengths. As a result, the visibility for =3650 relative to 4047 could be determined. It was also possible to estimate the visibility for 3130.