Lamp Intensity Research Articles

Light-Scattering Method in Particle Size Analysis of Parenteral Emulsions

The use of a light-scattering particle size distribution analyzer has been shown to be a convenient method for characterizing the particle size distribution of parenteral emulsions. However, the concentrations of the samples used were found to have a major impact on the particle size distribution results, particularly for samples with a mean particle size smaller than 0.2 µm. An increase in sample concentration caused a shift to smaller particle sizes as a result of multiple scattering. The blue-light (tungsten lamp) intensity, instead of the He-Ne laser integrity, should be used to control sample concentration within the optimal range for measurement.

Optical studies of anisotropic networks in polymer‐stabilized liquid crystals

Abstract— Polymer‐stabilized liquid crystals form a class of unique materials in advanced flat‐panel‐display technology. We have synthesized azo‐containing diacrylate monomers and have used their dichroic nature to study the anisotropic nature of the polymer network formed upon photopolymerization in a nematic solvent in 5‐ and 10‐μm cells. The effects of monomer structure, concentration, and UV dose on the order parameter have been studied. While order parameter does not appear to be dependent upon the intensity of the UV light used in the polymerization, SEM photos and electro‐optic studies of the cells indicate a dependence of the network morphology and cell response on UV lamp intensity.

The photoreduction of acetylene by band-gap irradiation of TiO 2 using Mo 2O 4 (diethyldithiocarbamate) 2 as a catalyst

The photoreduction of acetylene is catalyzed by Mo 2O 4(dedtc) 2 (dedtc, diethyldithiocarbamate) in the presence of 5–8 nm diameter colloidal TiO 2. This photocatalytic process exhibits optimum activity at pH 6 and a loading of 30 catalyst molecules per TiO 2 particle. The same catalytic site(s) are responsible for C 2H 2 reduction to C 2H 4 and C 2H 6 and H + reduction to H 2. The overall photonic efficiency is 1.3% for the transfer of reducing equivalents to products at full lamp intensity, and increases with decreasing intensity. The effects of pH, temperature, intensity and loading on the catalytic process are consistent with a mechanism in which the catalytic site associated with the TiO 2 surface promotes the transfer of H atoms or electrons to the bound substrate. The photocatalytic properties of this neutral molecular complex are compared with those observed for other Mo-containing catalysts.

Influence of lamp intensity and water transmittance on the UV disinfection of water

The efficiency of UV disinfection devices depends on flow, lamp intensity and water transmittance. In practice the flow is controlled by suitable methods, whereas the other two parameters, to date, have not been taken into consideration sufficiently. The surveillance of the function of UV disinfection plants is routinely based on a sensor placed on the irradiation chamber wall. This measures changes of UV irradiance without differentiating if the effect is caused by transmittance or lamp intensity so that two different conditions of disinfection may occur at the same sensor readings. We investigated the influence of transmittance vs intensity on disinfection at the same sensor readings in a specially designed laboratory flow through UV irradiation system with one single UV lamp as well as in commercially available UV disinfection plants with multiple UV lamps. All devices were equipped with a calibrated selective UV detector connected to a UV radiometer. Lamp intensity was decreased by diminishing the supply voltage. UV transmittance was reduced by pumping aqueous sodium thiosulphate solution into the water inflow. The disinfection capacity was determined by measuring the reduction equivalent doses (RED) using a standardised biodosimetric method. We showed that equal sensor readings, either achieved by reducing the lamp intensity or by lowering the UV transmittance of the water, resulted in different REDs in one-lamp systems. The diminishing of UV intensity caused a greater decrease of REDs than reducing the water transmittance. However, in the multiple-lamp systems tested, equal sensor readings yielded equal REDs.

A small-scale outdoor plant growth chamber with modulated enhancement of solar UV-B radiation.

An outdoor, solar illuminated growth chamber with modulated UV-B enhancement, is described and its performance characterized. The chamber was clad with Teflon film that transmitted both UV-A and UV-B with little absorption and whose transmission did not change significantly over 1 yr. An array of UV-B emitting fluorescent tubes with cellulose diacetate filters provided additional UV-B radiation inside the chamber with little additional UV-A, while a similar chamber with unenergized tubes provided an ambient control. Ambient and enhanced UV-B levels were measured using a pair of integrating broad band radiometers, and it was found that frequency modulation allowed control of lamp intensity over a range in excess of 100:1. Within the UV-B chamber, enhanced levels of integrated UV-B could be maintained at a constant ratio over ambient throughout the day. However, it was not sufficient simply to maintain a constant ratio of radiometer output voltages: the angular responses of the two radiometers had to be well matched. The shape of the UV-B portion of the enhanced spectrum closely followed that expected under ozone depleted skies, while the enhancement of UV-A was insignificant. The spectral profile obtained in the UV-B depended on the thickness of the cellulose diacetate filters used to block short wavelength UV radiation emitted by the fluorescent tubes. The number (thickness) of cellulose diacetate filters required to achieve this match varied with season. Although the filters did degrade with exposure to UV-B it was not necessary to replace them for several months. This was due to: (i) low rate of filter degradation because the lamps were rarely required to be run at full brilliance except at midsummer midday; and (ii) increased tube intensity compensated for reduced filter transmission.

UV intensity measurement for a novel 222 nm excimer lamp using chemical actinometer

Photohydrate of uridine in neutral aqueous solution is used for the determination of the ultraviolet (UV) intensity of a novel excimer lamp, employing a dielectric barrier discharge in krypton chloride to provide intense narrow band radiation at λ=222 nm (KrCl*). The intensity measurement is based on UV spectral absorption data. A photokinetic model is presented for the reaction which is generally applicable for any photochemical system. The electrical power dependence of the UV intensity generated as well as the efficiency of the lamps was investigated.

Photoinitiated cationic ring-opening polymerization of a cyclosiloxane

Hexamethylcyclotrisiloxane was found to undergo photoinitiated cationic ring-opening polymerization in solution and bulk, upon exposure to UV radiation, in the presence of either sulfonium or iodonium salts or an iminosulfonate derivative. Glass transition temperatures were below −100 °C. Molecular weights, determined by size exclusion chromatography relative to polystyrene standards, increased with photolysis lamp intensity. Use of an iodonium photoinitiator afforded poly(dimethylsiloxane) with Mn=172,000. Polymerization of hexamethylcyclotrisiloxane was accompanied by a small increase in volume (3–4%).

Influence of lamp intensity and water transmittance on the UV disinfection of water

The efficiency of UV disinfection devices depends on flow, lamp intensity and water transmittance. In practice the flow is controlled by suitable methods, whereas the other two parameters, to date, have not been taken into consideration sufficiently. The surveillance of the function of UV disinfection plants is routinely based on a sensor placed on the irradiation chamber wall. This measures changes of UV irradiance without differentiating if the effect is caused by transmittance or lamp intensity so that two different conditions of disinfection may occur at the same sensor readings. We investigated the influence of transmittance vs intensity on disinfection at the same sensor readings in a specially designed laboratory flow through UV irradiation system with one single UV lamp as well as in commercially available UV disinfection plants with multiple UV lamps. All devices were equipped with a calibrated selective UV detector connected to a UV radiometer. Lamp intensity was decreased by diminishing the supply voltage. UV transmittance was reduced by pumping aqueous sodium thiosulphate solution into the water inflow. The disinfection capacity was determined by measuring the reduction equivalent doses (RED) using a standardised biodosimetric method. We showed that equal sensor readings, either achieved by reducing the lamp intensity or by lowering the UV transmittance of the water, resulted in different REDs in one-lamp systems. The diminishing of UV intensity caused a greater decrease of REDs than reducing the water transmittance. However, in the multiple-lamp systems tested, equal sensor readings yielded equal REDs.

Characterization of photocurable coatings using fluorescence probes

AbstractIn this paper, we describe a novel method for monitoring the degree of cure and coating thickness of photocurable resins using intramolecular charge transfer (ICT) fluorescence probes such as 5‐dimethylaminonaphthalene‐1‐sulfonyl‐n‐butylamide (DASB) and 6‐propionyl‐2‐(dimethylamino)‐naphthalene (PRODAN). As the curing reaction proceeded, the fluorescence emission spectra of the ICT probes were found to exhibit hypsochromic spectral shifts because of the increase in matrix microviscosity, which made it more difficult for the excited molecule to relax to its twisted charge transfer state. The spectral changes of the probes as a function of the degree of the cure were monitored using a fluorescence intensity ratio method, which enabled an internal calibration of fluctuations in lamp intensity and sample thickness. It was found that the ratios of the fluorescence emission intensities at two different wavelengths were correlated linearly with the degree of polymerization for different types of acrylic or unsaturated polyester resins using either UV or visible (VIS) initiators. The coating thickness of photopolymers was measured based upon the nascent fluorescence from the coating substrate by virtue of an emission (from the substrate) and adsorption (by the coating) mechanism. The thicker the coating, the less the nascent fluorescence emission that can be observed. So the intensity of the nascent fluorescence from the substrate can be correlated to the coating thickness.

Analysis of Factors on Discernment of Auxiliary Lamps of Motorcycles.

Mounting auxiliary lamps similar to the front position lamps is an effective means of improving the visibility of motorcycles. Among possible factors which may influence discernment of the auxiliary lamps, the authors have examined factors such as the surface area, luminous intensity and luminance of the auxiliary lamps conducting outdoor experiments. The auxiliary lamp is made up of amber-colored light emitting diodes (LED) with 32 LEDs in the horizontal direction and 16 LEDs in the vertical direction. The experiments consist of two parts, a static experiment in which the observers observed a stationary motorcycle and a dynamic experiment in which they observed a moving motorcycle. The observers were instructed to evaluate the following three items:(1) Conspicuousness of the motorcycle(2) Brightness of the auxiliary lamps(3) Appropriateness of the auxiliary lamps.Experimental results and discriminant analysis of the data show that the luminous intensity of the auxiliary lamps strongly influences how the lamps are discerned.

Photometric Requirements for Arrow Panel Visibility

Laboratory and field studies were conducted using older drivers to identify the minimum lamp intensity needed for legibility of arrows and chevrons on Type C arrow panels (APs). A field study was also conducted to determine the maximum intensity required to control disability and discomfort glare at night. Ninety-fifth-percentile data were used to represent worst-case conditions. These data were combined with the results of an analytic study to identify the angularity required for the APs to perform in all geometric situations that conform to accepted standards. The results of the research provide a specification for AP lamps that will result in the proper identification of the AP message by drivers of all ages under most conditions, at distances of up to 467 m (1,500 ft) or greater at all angles that may be anticipated, and at distances of more than 1/2 mi on-axis. Further, the specification developed sets of minimum and maximum intensity levels for nighttime operations.

Photometric Requirements for Arrow Panel Visibility

Laboratory and field studies were conducted using older drivers to identify the minimum lamp intensity needed for legibility of arrows and chevrons on Type C arrow panels (APs). A field study was also conducted to determine the maximum intensity required to control disability and discomfort glare at night. Ninety-fifth-percentile data were used to represent worst-case conditions. These data were combined with the results of an analytic study to identify the angularity required for the APs to perform in all geometric situations that conform to accepted standards. The results of the research provide a specification for AP lamps that will result in the proper identification of the AP message by drivers of all ages under most conditions, at distances of up to 467 m (1,500 ft) or greater at all angles that may be anticipated, and at distances of more than ½ mi on-axis. Further, the specification developed sets of minimum and maximum intensity levels for nighttime operations.

Multiple wavelength aerosol photoemission by excimer lamps

Submicron aerosol particles of carbon, different metals and exhaust particles from a diesel engine are characterized via the charge p they obtain by photoelectron emission when irradiated by specially designed excimer lamps. The high intensity of these monochromatic lamps makes it possible to charge all particles to the limit defined by Coulomb recapture of the electron. This maximum charge p max( R, ( Φ) depends only on the particle radius R and photothreshold Φ ∞ and can therefore be used for identification and separation of different materials as well as detection of small changes in the state of the surface in terms of the outermost atomic layer. The latter effect is demonstrated on C, Cu and diesel particle coated with Zn or surface oxidized with O 3. The function p max( R, Φ) for spherical particles holds well for agglomerated structures, if particle size is defined by the electric mobility of the particles. As long as less than 10% of p max are reached at short radiation time or small intensity, the photoemission probability μ linearly depends on a photoemission parameter c related to the absorption behaviour of the particles. The charge distribution under these conditions is explained by Poisson statistics. The parameters Φ ∞, c and R can all be determined using excimer lamp photoelectric sensors containing lamps of different wavelengths. Excimer lamps represent an interesting alternative to conventional charging principles in electrostatic precipitators for gas cleaning.

Sensing oxygen through skin using a red diode laser and fluorescence lifetimes

The most difficult impediments to transcutaneous optical sensing are the absorbance and scatter of light caused by skin and the lack of fluorescent sensing probes which can be excited at wavelengths over 600 nm. Furthermore, current optical sensing techniques rely on absorbance or fluorescence intensity measurements, both of which are sensitive to drifts in lamp intensity, changes in probe concentration and inner filter effects. We demonstrate oxygen sensing through a layer of skin by using red light which readily penetrates skin as diffusely scattered light. The oxygen sensitive osmium-ligand complex used in this study can be excited at 635–680 nm. In addition, we measure fluorescence lifetimes, which are inherently unaffected by factors that limit absorbance and fluorescence intensity measurements. By using phase fluorimetry and long lived fluorophores, we are able to demonstrate the potential for subdermal oxygen sensing with simple and inexpensive instrumentation. This work describes a paradigm for future non-invasive measurements of other analytes.

Monte Carlo Simulation of Optical Temperature Sensors in RTP Systems

AbstractWe present simulation and experimental results for determining the distribution of radiation throughout an RTP system and evaluating the design of optical temperature sensors. The simulations are performed with a general purpose, three dimensional Monte Carlo method. The simulation models internal reflection, absorption, and transmission within participating media explicitly, and includes wavelength, temperature, and material dependent properties. Simulation results are compared to measurements of the lamp intensity profile within the lamphouse and at possible sensor locations. Simulations are used to examine the effect of several optical probe designs. The predicted responses of potential sensor designs resulting from these studies are presented.

Optical sensing of oxygen using phosphorescence quenching

Optical measurements that exploit the ability of oxygen to quench the photoexcited states of other molecules provide an alternative to the standard electrochemical and paramagnetic methods of measuring molecular oxygen concentration. In the present work we have re-examined the phosphorescence quenching technique as a means of monitoring oxygen concentrations in a gas stream at room temperature. Camphorquinone (CQ) is selected because it has strong absorption and emission bands in the visible region, enabling the use of inexpensive silica fibre-optic light guides. Determination of oxygen in the range 0.1–25% is easily achievable and, for a 10 μm thick PVC film containing CQ, the time to attain 90% response is of the order of 10 s. Photooxidation and photoreduction account for a significant loss of material under certain conditions of illumination and film composition. The use of triplet lifetime as a measure of oxygen concentration offers several advantages. In particular, by using an intrinsic property of the sensing molecule, variations in lamp intensity and photomultiplier sensitivity are avoided and the effects of photobleaching reactions are minimized.

A 3-Dimensional Temperature Uniformity Model for a Rapid Thermal Processing Furnace

ABSTRACTA fully three dimensional model has been developed for simulating the thermal behaviour of a RTP furnace. This model consists of two components to achieve the whole analysis. The first component models the radiation heat flux density at the wafer surface as a function of the system geometry, the lamp position and intensity, and the wall reflectivities. The second component solves the heat conduction equation at each point within the wafer using appropriate boundary conditions, including convective cooling which effect depends on the process conditions. A particular attempt is made upon the achievement of a flat temperature profile over the wafer by investigating the system parameters in order to improve the RTP equipement.

Determination of lead at low concentrations in food samples by electrothermal atomic absorption spectrometry

A method for the determination of Pb in biological materials by electrothermal atomic absorption spectrometry was tested at a wavelength of 217.0 nm and with 0.1% Pd as the chemical modifier. A Varian SpectrAA 400 Zeeman spectrometer equipped with a Photron Pb Superlamp was employed. As the contents of Pb in most biological materials are near the limit of detection, peak height measurement and the method of standard additions were used. The validity of the method was tested using the following ARC/CL-coded reference materials: wheat flour, potato powder, milk powder and animal muscle, in addition to various other commercial reference materials. Recovery tests were made on some reference materials. The accuracy of the method was satisfactory for the tested materials. High lamp intensity and the most sensitive Pb wavelength resulted in better characteristic masses; the characteristic mass in peak height mode at 283.3 nm with a hollow cathode lamp was usually 5–8 pg and at 217.0 nm with the Superlamp, 3–5 pg, depending on the sample matrix. Low backgrounds were measured in the sample materials. Ammonium phosphate cannot be employed as the chemical modifier when using the 217 nm line, as phosphate species cause spectral interferences at that wavelength.

Use of reflectance spectra to predict heat buildup of pigmented PVC panels

AbstractWe present a method for predicting the heat buildup of pigmented PVC panels. Vinyl panels prepared for use in the ASTM D4803‐89 heat buildup test are scanned for percent reflectance from 200 to 2500 nm. For each sample an intensity factor is calculated according to: where IF = intensity factor, Rλ = fractional reflectance of the sample at 20 nm intervals, and Lλ = relative intensity of the heat lamp at 20 nm intervals. A plot of the IF for each sample vs. its measured heat buildup (ASTM D4803‐89) for more than 50 sample panels containing a wide variety of pigments shows a linear relationship. Thus, the result in the ASTM D4803‐89 heat buildup test can be predicted based on the sample's reflectance spectrum and the intensity factor calculation. This method makes running the heat buildup test unnecessary and is very useful in evaluating pigments and pigmented systems for relative coolness.

Electric lamps, past and present

The article traces the story of the electric lamp, which began when, in 1810, Davy demonstrated the now legendary ‘bright carbon arc’ that led, in 1850, to the production of practical arc lamps. Because of the ‘powerful’ intensity of the arc lamp, there was a demand for ‘the subdivision of light’ and this culminated, in 1879, in the invention of the incandescent filament lamp. Gaseous and vapour discharge lamp research began around 1850 and practical lamps were available in the early 1900s. There were carbon dioxide, nitrogen and neon filled tubes giving ‘daylight’, ‘sunlight’ and red light emissions, respectively. Also, and still available, there were high-voltage, mercury vapour, cold-cathode fluorescent tubes. Following research in the early 1930s mains voltage, high- and low-pressure mercury and sodium vapour lamps have been under constant development and they are widely used today. Fluorescent lamps, introduced in 1938, are regularly being improved in design and among the latest are compact energy saving types that are ideally suited, as direct replacements, for GLS lamps. The recent announcement of the QL induction lighting system is the latest milestone in ‘electric light’ invention.