Showing papers on "Transmittance published in 1993"

Nonlinear absorption study of a C 60 -toluene solution

Abstract: Nonlinear absorption at 532 nm in a C60–toluene solution by using 8-ns and 30-ps laser pulses is reported. The transmittance for both pulse widths is fluence dependent. A five-level model of C60 is described that yields excellent agreement with both pulse-width data sets for incident fluences as high as approximately 1 J/cm2. Additional phenomena observed at higher fluences indicate that other mechanisms may be active and contribute to optical limiting in this regime. The application of C60 as an optical limiter material is discussed.

Vanadium oxide films for optical switching and detection

Abstract: Structural, electrical, and optical properties of the polycrystalline films of VO2, V2O5, and mixtures of these two oxides are presented. Resistivity change by a factor larger than 103 accompanying the semiconductor-metal phase transition in the VO2 films is reported. A significant contrast in optical transmittance for the two phases of VO2 is observed. High temperature resistivity and optical transmittance of the V2O5 films are shown. Values of the temperature coefficient of resistance in some of the VO2 films in their semiconducting phase and in some of the V2O5 films are as high as 5.2 and 4% per degree Celsius, respectively. Phase switching properties of the VO2-V2O5 films are described. Applications of the fabricated films include optical switches and bobmetric-type light detectors.

Electrical and optical characterization of Sb : SnO2

Abstract: Films of Sb : SnO2 have been formed by vacuum e-beam evaporation. The structural, electrical, and optical properties of these films have been investigated with respect to annealing time and temperature. After heat treatment in an oxygen atmosphere, thin films with a peak transmittance of 98% and 4–9 × 10−3 Ωcm resistivity have been obtained. The barrier heights and energy band diagrams of Sb : SnO2/Si n-n and p-n heterojunctions have been determined by C-V measurements.

Dark gray, infrared absorbing glass composition and coated glass for privacy glazing

Abstract: A neutral, dark gray, soda-lime-silica glass having luminous transmittance less than 35 percent, infrared transmittance less than 20 percent, and total solar energy transmittance less than 22 percent (all at 3.9 millimeter thickness) is produced with colorants consisting essentially of 1.0 to 2.2 percent by weight total iron, at least 0.20 percent FeO, 0.01 to 0.03 percent CoO, and 0.0005 to 0.005 percent Se. The flat glass product having such a composition is particularly suitable for use as privacy glazing. The use of the glass as a substrate for a reflectively coated product is also disclosed. A low transmittance, reflective coated article is disclosed comprising a soda-lime-silica glass substrate having luminous transmittance less than 35 percent, infrared transmittance less than 20 percent, and total solar energy transmittance less than 22 percent (all at 3.9 millimeter thickness) and a metal oxide coating having a luminous reflectance not more than 25 percent from the coated surface, and not more than 8 percent from the uncoated surface. The low transmittance coated glass product is particularly suitable for use as privacy glazing.

Stand-alone photovoltaic (pv) powered electrochromic window

Abstract: A variable transmittance double pane window includes an electrochromic material (16) that has been deposited on one pane of the window (12) in conjunction with an array of photovoltaic cells (60) deposited along an edge of the pane to produce the required electric power necessary to vary the effective transmittance of the window. A battery is placed in a parallel fashion to the array of photovoltaic cells to allow the user the ability to manually override the system when a transmittance is desired.

Optical coatings deposited by reactive ion plating.

Abstract: The effect of different reactive ion-plating process parameters on the transmittance and the reflectance of single layers of HfO2, Ta2O5, and SiO2 are investigated. The optical constants obtained for these three as-deposited materials are presented. Laser-damage threshold trends are examined on single- and double-layer coatings at 1064 nm and on high-reflectance coatings for 248 nm. Single- and double-cavity filters are constructed for the UV (<1-nm bandwidth) and near-infrared (50-nm bandwidth) regions, respectively. After the filters are postannealed in air at 375 °C for several hours, a shift in the peak wavelengths is observed along with a substantial increase in the peak transmittance. As expected, no significant wavelength shifts result from changes in the humidity of the ambient atmosphere.

High visible, low UV and low IR transmittance green glass composition

Abstract: A soda-lime-silica green glass favoring the yellow side, rather than the bluish side of the spectrum, is produced having high visible transmittance, low infrared energy transmittance, low ultraviolet radiation transmittance, and low total solar energy transmittance by manipulating the reduction of iron (as Fe₂0₃) to Fe0 and the percent of these two oxides to achieve these characteristics without the use of Ce0₂ or other UV absorbing additives and by using conventional glass melting and refining apparatus.

Analytical determination of the optical performance of practical parabolic trough collectors from design data

Abstract: A semifinite analytical formulation is presented to facilitate the efficient numerical computation of the concentrated radiant flux on receiver surfaces in the parabolic trough concentrator. The concentrated flux density is integrated to yield the interceptance ratio for the collector. By including models for the incident-angle dependent envelope transmittance and receiver absorptance, the concentration ratio for absorbed radiation is also calculated and integrated to yield the optical efficiency. Flux distribution results from this detailed analysis are compared with a point source model, and the optical efficiency results are compared with a first-order model. Since this model includes both a realistic nonuniform solar modeling as well as models for imperfect reflection, transmission, and absorption, it is capable of estimating the optical efficiency of practical collectors.

Plastic container sorting system and method

Abstract: A plastic container sorter (10) moves labeled plastic containers (14, 20, 48, 54, 58) of various colors and transparencies through an inspection zone (18). A pair of line-scanning color cameras (22, 24) capture respective transmittance and reflectance images of the containers and generate raw transmittance and reflectance image data. The raw container data are digitized, normalized, and binarized to provide accurate transmittance and reflectance container RGB image data and binarized image data for differentiating container image data from background data. Container sorting entails eroding (120) the binarized transmittance image and merging (122) the eroded image with the transmittance image data to yield a transmittance image. The eroded transmittance image is analyzed (124, 126) to determine whether the container is opaque. If the container is opaque, color analysis proceeds by analyzing the reflectance image data. If, however, the container is not opaque, transmittance image data are used to classify the container as green transparent (140), translucent (142), or clear transparent (142). Classified containers are transferred to an ejection conveyor (46). Side discharge of a classified container is effected by an air ejector (64) blast that is timed in response to sensing a particular container adjacent to an appropriate side discharge station (60).

Analysis of spatial scanning with thick optically nonlinear media

Abstract: The refractive and absorptive response of a nonlinear material can be assessed by the use of a spatial scanning technique to characterize the material. This technique generally involves monitoring the normalized trans-mittance of an optical beam focused into a sample of the material. In this paper an analytic solution of the beam propagation equation correct to the first nonlinear order has been obtained for the situation in which the sample has a thickness greater than the depth of focus. In this context simple exact formulas have been obtained for the cumulative phase and the normalized transmittance of a focused beam at any position along the optic axis, and the expressions have been used to investigate the various possible scanning techniques.

Simulation of fan-beam-type optical computed-tomography imaging of strongly scattering and weakly absorbing media.

Abstract: Numerical simulations of the transmission of a light impulse through strongly scattering and weakly absorbing slab media and of fan-beam-type optical computed-tomography imaging for cylindrical media are presented. A hybrid calculation scheme of scattering by the Monte Carlo method is employed to obtain the temporal variation of transmittance of the light impulse through the media. A set of projection data is provided by temporally extrapolating the difference in the optical density between the absorbing object and the nonabsorbing reference to the shortest time of flight. For the case of identical scattering between the object and reference, the reconstructed image of the difference in the absorption coefficient has better accuracy and spatial resolution than those images by the time-gating method.

Light attenuation length of barium fluoride crystals

Abstract: This report presents a deduction of a formula which can be used to calculate the light attenuation length of barium fluoride crystals based on the transmittance (or absorbance) data measured by a spectrophotometer

Neutral gray-green low transmittance heat absorbing glass

Abstract: A heat absorbing, neutral gray to green, soda-lime-silica glass having at 4 mm. control thickness a light transmittance using illuminant A of 10.0% to 60.0%, ultra violet transmittance less than 25.0%, infra red transmittance is less than about 50.0%, and the purity of excitation is less than 6.0% which is produced from colorants consisting of 0.90 to 1.90 percent by weight total iron oxide as Fe 2 O 3 , 0,002 to 0.025 percent Co, 0.0010 to 0.0060 percent Se, and 0.1 to 2.0 percent TiO 2 . The flat glass products having such a composition is particularly suitable for use as a privacy glass or sun roof product in trucks and automobiles.

Nonlinear optical properties of the fullerenes C60 and C70 at 1.064 microm.

Abstract: Time-resolved degenerate-four-wave-mixing experiments were conducted on films of pure C 60 and C 70 using a 35-ps laser at 1.064 μm. The fullerenes exhibit a two-photon resonantly enhanced third-order optical response that is primarily laser-pulse-limited. At high laser intensities, a fifth-order component to the nonlinear optical signal is observed and is attributed to a two-photon excited-state transient grating. The large two-photon absorption coefficients measured for C 60 and C 70 at 1.064 μm by nonlinear transmittance are consistent with this assignment

Analysis and design of transparent conductive coatings and filters

Abstract: Four types of transparent electrically conductive filters commonly used for a variety of applications are (1) a free-standing conducting inductive mesh, (2) a substrate coated with a conducting inductive mesh, (3) a conducting substrate, and (4) a substrate coated with a continuous conducting coating. Each can be designed to provide high visible, near infrared, and/or far infrared transmittance and high radio frequency (rf) and/or microwave attenuation. Theoretical models developed at Itek to predict the optical, rf, and electrical properties of each type of filter as a function of conductivity, relaxation time, electronic mobility, thickness, mesh period, and mesh line width are described. The temperature and angle of incidence dependence are also discussed. Simple expressions for predicting the performance of these four types of filters at both optical and rf frequencies provide both insight and useful starting designs.

Polysilicon pixel electrode

Abstract: A liquid crystal display wherein each pixel has a thin film transistor with a silicon pixel electrode. A doping and recrystallization of the silicon is effected to increase the electrical conductivity and light transmittance of the silicon adequately for the pixel electrode.

Variable reflectance mirror

Abstract: The present invention provides variable reflectance mirrors wherein the component of variable transmittance is a single-compartment, self-erasing, solution-phase electrochromic device.

Liquid crystal devices comprising a multitude of domains having different threshold voltages for switching liquid crystals

Abstract: A liquid crystal device comprises a pair of substrates and a liquid crystal provided between the paired substrates wherein domains whose threshold voltages are different from one another are finely distributed throughout the liquid crystal. In particular, the respective substrates each has a transparent electrode and an alignment film formed thereon in this order and the substrates are assembled to establish a given space therebetween, and a ferroelectric liquid crystal being injected into the given space wherein domains are finely distributed as set out above, thereby providing a a liquid crystal display device. The fine distribution is such that when a transmittance through inverted domains is 25%, the number of domains (microdomains) having a size of larger than 2 μmφ in a field of 1 mm2 is not smaller than 300, preferably not smaller than 600, and the width of the threshold voltage within the domains is not smaller than 2 volts within a transmittance range of from 10 to 90%. The liquid crystal device, particularly the display device, keeps a high contrast and can easily, reliably realize an analog gray-scale display at low costs.

Method of manufacturing liquid crystal display device

Abstract: In a method of manufacturing a liquid crystal display device of this invention, a light transmittance of an overcoating layer of the liquid crystal display device is partially reduced to form a part of a light-shielding portion. Therefore, a color filter can be easily formed, and hence the device can be manufactured at high productivity and low cost.

Color liquid crystal display device

Abstract: PURPOSE:To make it possible to increase transmittance and to sufficiently enhance the brightness of display by diagonally shifting the transmission axes of a pair of polarizing plates at a prescribed angle from the optical axis of a phase plate, thereby coloring the transmitted light without using color filters. CONSTITUTION:This color liquid crystal display device consists of a liquid crystal cell 30 which is constituted by sealing a liquid crystal 38 between a pair of transparent substrates 31 and 32 formed with transparent electrodes 33, 34 and in which the molecules of the liquid crystal are twist oriented at 180 to 270 deg. twist angle between both substrates 31 and 32, a pair of the polarizing plates 42 which are arranged on both sides of the liquid crystal cell 30 held therebetween and the phase plate 40 which is arranged between the liquid crystal cell 30 and one of the polarizing plates 41, 42. The transmission axes 41a, 42a of a pair of the polarizing plates 41, 42 are shifted diagonally at the prescribed angle with the optical axis of the phase plate 40. Then, the transmitted light is colored without using the color filters and the quantity of the light is substantially the same as the quantity of the light of a wavelength where the coloring light is formed among the incident light rays on the display device. The transmittance of the light is thus increased and the sufficiently high brightness of the display is obtd.

Refractive index and scattering effects on radiative behavior of a semitransparent layer

Abstract: Heat transfer characteristics are analyzed for a plane layer of semitransparent material with refractive index not less than 1. Energy transfer in the material is by conduction, emission, absorption, and isotropic scattering. Each side of the layer is heated by radiation and convection. For a refractive index larger than unity, there is internal reflection of some of the energy within the layer. This, coupled with scattering, has a substantial effect on distributing energy across the layer and altering the temperature distribution from when the refractive index is unity. The effect of scattering is examined by comparisons with results from an earlier paper for an absorbing layer. Results are given for a gray medium with a scattering albedo up to 0.999, and for a two-band spectral variation of the albedo with one band having low absorption. Radiant energy leaving the surface as a result of emission and scattering was examined to determine if it could be used to accurately indicate the surface temperature.

Light transmittance of ocular media in living rabbit eyes

Abstract: Purpose The purpose of this study was to measure the transmittance of electromagnetic radiation, particularly visible light, through the ocular media of living and whole rabbit eyes. Previous determinations have been carried out on excised cadaver eyes. Methods A specially designed fiberoptic probe (outer diameter, 0.9 mm) was placed in the vitreous in front of the retina using a microsurgical technique. In eight living albino rabbits (under general anesthesia), ocular transmittance was determined in the wavelength range 350 to 1100 nm using a reversed beam path (from vitreous to cornea). Results A maximum optical transmittance of 94% to 96% (standard deviation, 2%-3%) was found between 630 and 730 nm (reflection losses in the cornea-air interface excluded). In the blue portion of the spectrum, transmittance decreased rapidly for shorter wavelengths, and was 50% at 400 nm and less than 1% at 380 nm. In the infrared part of the spectrum, transmittance was close to 90% up to 900 nm but declined at longer wavelengths, coinciding with the absorption in pure water. Calibration recordings showed a 1% to 2% accuracy of the method. Conclusions This experimental technique using an intraocular fiberoptic probe yields a high accuracy and indicates that light transmittance is very high in vivo and superior to that reported from cadaver eyes.

High endurance near-infrared optical window

Abstract: Multilayers of low refractive index amorphous silicon nitride and high refractive index amorphous silicon are interleaved to construct a near-infrared optical filter. For an edge filter, the structure is transparent to near-infrared light and opaque to visible light. For a band-pass filter, the low-pass filter is superimposed with a high-pass filter. Anti-reflection coating can be added to improve the transmittance. These multilayers are deposited with Plasma Enhanced Chemical Vapor Deposition technique.

A novel switchable glazing formed by electrically induced chains of suspensions

Abstract: Chains of submicron size rodlike TiO x N y particles, formed along an electric field by the so‐called electrorheological effect, were softly fixed in a silicone elastomer film interposed between a pair of indium–tin oxide glasses. It has been found that the transmittance of the device was remarkably changed by displacing one substrate relatively to the other. This transmittance variation was linear with the relative displacement between substrates. For a displacement of about 35 μm, a solar transmittance change of 40.7% was obtained, while it was below 6.9% for a cell containing TiO2 particles. The excellent optical properties of the cell using TiO x N y particles as switchable glazing was imputable to the large absorption coefficient of the particles over the wavelength of the solar spectrum (∼105 cm−1) and to a drastic variation in the cross‐sectional area of the particle chain for the light when submitting the substrates to shear stress. This new type of the switchable glazing was referred to as ‘‘shear stress‐type dipole particle chain in elastomer.’’

Filters for the International Solar Terrestrial Physics Mission far-ultraviolet imager

Abstract: The far ultraviolet (FUV) imager for the International Solar Terrestrial Physics (ISTP) mission is designed to image four features of the aurora: O I lines at 130.4 nm and 135.6 nm and the N2 Lyman-Birge-Hopfield (LBH) bands between 140 nm - 160 nm (LBH long) and 160 nm - 180 nm (LBH long). In this paper we report the design and fabrication of narrow-band and broadband filters for the ISTP FUV imager. Narrow-band filters designed and fabricated for the O I lines have a bandwidth of less than 5 nm and a peak transmittance of 23.9 percent and 38.3 percent at 130.4 nm and 135.6 nm, respectively. Broadband filters designed and fabricated for LBH bands have the transmittance close to 60 percent. Blocking of out-of-band wavelengths for all filters is better than 5x10(exp -3) percent with the transmittance at 121.6 nm of less than 10(exp -6) percent.