We have observed three kinds of Raman scattering spectra for the following materials: (1) the bamboo-based carbon filaments inside historical incandescent lamps fabricated by Ichisuke Fujioka and Thomas A. Edison, whose results were compared with those of a bamboo-based carbon filament annealed in our laboratory and a broken filament extracted from the incandescent lamp, which has been preserved for over a hundred years by our company; (2) iodine deposited inside a Hg-free high-intensity discharge (HID) lamp after arc discharge in a xenon (Xe) atmosphere, and (3) the variation in the spectra for PEDOT (poly(3,4-ethylenedioxythiophene)) doped with PSS (polystyrene sulfonate) and the PEDOT:PSS electrochemically dedoped. A shift in the D-band owing to defects was found to be 52 cm-1/eV for the bamboo-based carbon filament extracted from the incandescent lamp. The spectrum of iodine deposited inside the Hg-free HID lamp exhibited an erratic intensity progression with an overtone of more than 20, and this behavior was considered to be due to the resonance fluorescence of the gaseous iodine sublimated after the irradiation of laser light.
Systems containing mixtures of alkali metal halides and lanthanide halides are widely used in metal halide discharge lamps. This work describes the derivation of thermochemical data for the gaseous and condensed phases of the (NaI–CeI3) and (CsI–CeI3) systems thus enabling the calculation of partial pressures above a liquid mixture at temperatures found in such lamps. Information on the thermodynamic data and phase diagrams for binary CeI3-containing systems are limited. Similarities in behaviour between various alkali metal halides with different halides across the lanthanide (Ln) series have been exploited to estimate missing parameters for the condensed phases. This has been augmented by ab-initio quantum mechanics to derive thermodynamic properties for gas phase species.
Atomic and excitation temperatures were determined in medium-pressure (0.14 atm) mercury lamp working on square-wave current from radiance measurements of the red wing of the resonance mercury line 254 nm. The results were compared with these obtained using time resolved measurements at the maximum- and minimum current phase in a high-pressure (6 atm) mercury lamp operating with typical conventional electromagnetic ballast, and show that strong nonequilibrium phenomena occur in particular in the medium-pressure lamp. The excitation temperature was determined from the peak radiance using a non-LTE version of the Bartels method. The atomic temperature as well as the plasma pressure was then deduced from a non-LTE simulation of the line shape.
An innovative high efficiency xenon excimer lamp radiating at 172 nm has been built inside a section of a commercial compact fluorescent light (CFL) tube and has demonstrated the feasibility of a high efficiency mercury free white light source. Such lamps can be fabricated in various geometries and sizes and can operate with equal efficiency over wide temperature and power ranges. The excitation mechanism used is similar to that employed in mercury lamps, but without the power and geometry constraints of radiation trapping. This new system is highly compatible with phosphors as it operates at modest temperature in an inert gas and the 172 nm primary radiation is narrow band. A prototype fluorescent white light lamp achieved an efficacy of 90 lm/W. Higher values are projected. The lamp is rapidly switchable, is compatible with dimmers, and is expected to have long operating life.
The characteristics of the emission spectra of coaxial KrBr* excilamps are investigated with high electric power density ranging from 557 to 803 W/m driven by sinusoidal electronic control gear (ECG) as well as 367 to 546 W/m by pulsed ECG, based on the dielectric barrier discharge. The radiant power of intense narrow band ultraviolet radiation at 207 nm is derived from the irradiance according to Keitz formula while the input power is measured and compared by Lissajous figure and integration of voltage and current. It is shown that the measurement power of integration of voltage and current achieves more accuracy. And the radiant efficiency of 207 nm varies with the gas parameters, demonstrating an optimum 4.1% of energy converted to 207 nm band radiation at pressure 300 mbar and bromine percentage 0.25%.
Flickering is a phenomenon associated to light sources. This flicker is at 100 Hz in Europe and although at this frequency, people don't perceive it consciously, there could be some health impact. We examined the limits of visual perception so that we can determine whether flickering can be used to our benefit. The parameters of frequency and duty cycle were explored as well as the impact of the background color on the perception.
Even when not directly visible, flicker from light sources at frequencies exceeding 100 Hz can influence perception through stroboscopic effects. Three experiments were conducted to evaluate the impacts of flicker varying in frequency and modulation depth on visual performance, comfort and preference. In one experiment, subjects performed a numerical verification task under flickering illumination from 100 to 1000 Hz and from 25% to 100% flicker. Error rates were lower under higher frequency and lower flicker modulation and visual comfort was slightly higher. In the second experiment, subjects preferred higher frequency and lower modulation than 100 Hz, 100% flicker. In the third experiment, subjects equated perceived quality from illumination with higher frequency or lower modulation flicker when the illuminance was reduced by about half, relative to 100 Hz, 100% flicker. The results were consistent with a recently published model of the perception of stroboscopic effects.
Nocturnal outdoor illumination is mainly designed aiming at human needs. However, side effects on other organisms and ecosystems have to be expected, for example for fish populations. Basic knowledge about biological action of light on fish could be gained from laboratory experiments. This work presents an experimental strategy to study the biological action of light on fish. It is found that the melatonin expression of European perch (Perca fluviatilis) is significantly suppressed at an illuminance level of 100 lx throughout the night. The experimental approach is described in detail including biological methods, experimental illumination design and mathematical modeling for reconstruction of melatonin release rates from water melatonin concentrations.
The LED lighting fixture has the versatile advantages including energy saving, long life time, compact size, wide color range and easy dimming comparing with fluorescent lamp. Adjusting the color temperature of LED dynamic lighting fixture becomes an interesting application in interior lighting or sun light simulation. In this paper, the different types of LED (AC, HV, DC) for the dynamic lighting fixture are evaluated.