Incandescent Light Sources Research Articles

Analysis of photon recycling using metallic photonic crystal

We investigate a photon recycling scheme using two-dimensional metallic photonic crystals made of silver to improve the energy efficiency of an incandescent light source. A theoretical framework is presented to analyze the resultant photon-recycled lighting system. Calculation results show that the system can reach a maximum luminous efficiency of 125 lm/W, which is 8 times higher than that of a bare blackbody radiation at 2800 K. The color temperature of the system is calculated to be around 3500 K or below, while the color rendering index is between 68 and 90. These results suggest that a photon-recycled incandescent light source using metallic photonic crystals can be a viable alternative future lighting solution.

Relation between the illuminance responsivity of a photometer and the spectral power distribution of a source

The illuminance responsivity dependencies on spectral power distributions (SPDs) of different types of light sources are studied. In this work we used three types of calibrated photometers, one of which was home-made and two were commercial photometers. A monochromator-based facility was used to scan SPDs of light sources. The dependencies of spectral mismatch correction factors F(S t ,S s ) and the illuminance responsivities of photometers versus the SPDs of tungsten-filament incandescent, fluorescent, high-pressure sodium, and metal-halide light sources and white/colored light-emitting diodes are presented throughout this work.

Electrical characterisation of phosphorus-doped ZnO thin films grown by pulsed laser deposition

Abstract Phosphorus-doped ZnO films were grown by pulsed laser deposition using a ZnO:P 2 O 5 -doped target as the phosphorus source with the aim of producing p-type ZnO material. ZnO:P layers (with phosphorus concentrations of between 0.01 to 1 wt%) were grown on a pure ZnO buffer layer. The electrical properties of the films were characterised from temperature dependent Hall-effect measurements. The samples typically showed weak n-type conduction in the dark, with a resistivity of 70 Ω cm, a Hall mobility of μ n ∼0.5 cm 2 V −1 s −1 and a carrier concentration of n∼3×10 17 cm −3 at room temperature. After exposure to an incandescent light source, the samples underwent a change in conduction from n- to p-type, with an increase in mobility and decrease in concentration for temperatures below 300 K.

34th Annual Scientific Meeting of the Association of Paediatric Anaesthetists of Great Britain and Ireland, 8?10 March 2007, Manchester. Runner up for trainee prize Optimal spectral irradiance for laryngoscopy

Introduction: Changing the colour of light produced by laryngoscopes may improve the view at laryngoscopy and facilitate intubation. This could be crucial in children with anatomically difficult airways and in acute airway emergencies. Infra red light has been shown to be detrimental to optimal laryngoscopy (1). Anaesthetists have expressed a preference for blue/white light output to facilitate intubation (2). Blue light corresponds to peak haemoglobin absorption (415 nm) and therefore enhances the view of capillary vessels within the surface mucosa.(3) Green light defines deeper structures more clearly (3). Specific combinations of blue and green light spectra may provide the best conditions for intubation. Light Emitting Diodes (LEDs) have the advantage of producing light in a more appropriate part of the spectrum. LEDs are not currently used in laryngoscopes available in the UK. The aim of this study was to compare the spectral irradiance of the ProAct Miller 1 Paediatric blade laryngoscope (containing an incandescent bulb) with a custom-made laryngoscope containing an LED. Methods: The light spectral irradiance from the laryngoscope blades was measured under standardised conditions using the Bentham spectroradiometer. Blackout conditions were applied to eliminate background light. The tip of each laryngoscope blade was placed in contact with the sample port of the spectroradiometer. A mains voltage supply was set at 3 V for the Miller 1 blade (A) and 3.6 V for the blade with the LED (B), as specified by the manufacturers. Results: The Miller 1 paediatric blade produced spectral irradiance mainly in the infrared region (>660 nm) in contrast with the LED which produced most irradiance in the blue/green region of the spectrum (400–550 nm). (1) [ Spectral irradiance from the Miller 1 blade (A) and the blade with the LED (B). ] Discussion and conclusions: Paediatric laryngoscopes with LEDs may provide superior intubating conditions than that currently available with incandescent light sources. LEDs can be further modified to emit the optimal spectral irradiance required for laryngoscopy. This may prove invaluable when presented with a difficult airway. References 1 Crosby E, Cleland M. An assessment of the luminance and light field characteristics of used direct laryngoscopes. CanJ Anesth 1999; 46: 792–796. 2 Scholz A, Farnum N, Wilkes AR et al. Minimum and optimum light output of Mackintosh size 3 laryngoscopy blades: a manikin study. Anaesthesia 2007; 62: 163–168. 3 Watanabe A, Tsujie H, Taniguchi M, Hosokawa M, Fujita M, Sasaki S. Laryngoscopic detection of pharyngeal carcinoma in situ with narrow band imaging. Laryngoscope 2006; 116: 650–654.

Spectrophotometric Measurements of pH in-Situ: Laboratory and Field Evaluations of Instrumental Performance

Automated in-situ instrumentation has been developed for precise and accurate measurements of a variety of analytes in natural waters. In this work we describe the use of 'SEAS' (spectrophotometric elemental analysis system) instrumentation for measurements of solution pH. SEAS-pH incorporates a CCD-based spectrophotometer, an incandescent light source, and dual pumps for mixing natural water samples with a sulfonephthalein indicator. The SEAS-pH optical cell consists of either a liquid core waveguide (LCW, Teflon AF-2400) or a custom-made PEEK cell. Long optical path lengths allow use of indicators at low concentrations, thereby precluding large indicator-induced pH perturbations. Laboratory experiments show that pH measurements obtained using LCW and PEEK optical cells are indistinguishable from measurements obtained using conventional spectrophotometric cells and high-performance spectrophotometers. Deployments in the Equatorial Pacific and the Gulf of Mexico demonstrate that SEAS-pH instruments are capable of obtaining vertical pH profiles with high spatial resolution. SEAS-pH deployments at a fixed river-site (Hillsborough River, FL) demonstrate the capability of SEAS for observations of diel pH cycles with high temporal resolution. The in-situ precision of SEAS-pH is assessed as 0.0014 pH units, and the system's measurement frequency is approximately 0.5 Hz. This work indicates that in-situ instrumentation can be used to provide accurate, precise, and highly resolved observations of carbon-system transformations in the natural environment.

Visual investigations on radial solid holdup in vapor–liquid–solid fluidized bed evaporator with a CCD measuring system

In previous visual investigations on the hydrodynamic and heat-transfer characteristics in an external natural circulating evaporator with vapor–liquid–solid (V–L–S) boiling flow, a charge-coupled device (CCD) measuring system with a white light source was developed (Liu et al., 2004, studies on the hydrodynamic and heat transfer in a vapor–liquid–solid flow boiling system with a CCD measuring technique. Chemical Engineering Science 59(4), 889). In this approach, a three-dimensional flow field was transformed into a two-dimensional (2D) image and was recorded, and the holdup and the axial linear velocity distributions of solid particles in an axial location in a heated tube were estimated. However, the radial distribution of solid holdup has not been evaluated because the space position of each particle in a 2D image measured under an incandescent lamp light source is difficult to determine even though the particle overlapping does not appear. Hence, a CCD measuring system combined with a laser sheeting technique was chosen and developed to examine the solid holdup profile in the radial direction in a V–L–S fluidized bed evaporator by taking images of 2D flow fields in this work. The principles and steps are briefly elucidated and typical results are given. It is shown that the solid holdups in the radial direction in a heated tube are not uniform and the profiles vary with the flow regimes under the present experimental conditions. The solid holdups in the axis center are higher than those near the wall of the heated tube with the V–L–S boiling flow regime, while the opposite is true for the L-S flow regime. Asymmetric distributions of solid holdups in the radial direction are also obtained. Some likely qualitative explanations and demonstrations on experimental facts observed are given. This work may provide some valuable references for academic descriptions and industrial applications of such an installation.

Temperature-Controlled 830-nm Low-Level Laser Therapy of Experimental Pressure Ulcers

This study was performed to evaluate the effectiveness of near-infrared low-level laser therapy (LLLT) treatment of pressure ulcers under temperature-controlled conditions. Little information is available regarding the potential thermal effects of near-infrared photo-radiation during LLLT. Pressure ulcers were created in C57BL mice by placing the dorsal skin between two round ceramic magnetic plates (12.0 x 5.0 mm, 2.4 g, 1 K Gauss) for three 12-h cycles. Animals were divided into three groups (n = 9) for daily light therapy (830 nm, CW, 5.0 J/cm(2)) on days 3-13 post ulceration in both groups A and B. A special heat-exchange device was applied in Group B to maintain a constant temperature at the skin surface (30 degrees C). Group C served as controls, with irradiation at 5.0 J/cm(2) using an incandescent light source. Temperature of the skin surface, and temperature alterations during treatment were monitored. The wound area was measured and the rate and time to complete healing were noted. The maximum temperature change during therapy was 2.0 +/- 0.64 degrees C in Group A, 0.2 +/- 0.2 degrees C in Group B and 3.54 degrees C +/- 0.72 in Group C. Complete wound closure occurred at 18 +/- 4 days in Groups A and B and 25 +/- 6 days in Group C (p </= 0.05). The percentage of the wound closure at 14 days was 75. 4 +/- 7.2% and 77.7 +/- 5.6% for Groups A and B, respectively (NS differences). However, animals in Group C demonstrated a wound closure of 36.3 +/- 4.8% (p < 0.05). These results demonstrate that the salutary effects of LLLT on wound healing are temperature independent in this model.

Frankfurters — acceptability under different retail lights

Dark, medium, and light colour frankfurters (no-fat, low-fat, and regular fat level) were evaluated by panellists under incandescent (INC), fluorescent (FL), and metal halide (MH) light sources. INC illumination resulted in a higher colour preference (P &lt; 0.05) for the medium and light products over that of the FL and MH illuminations; no significant difference was seen between FL and MH lighting. The panellists described the medium coloured frankfurters as pink under INC lighting, but more brown under FL and MH illumination. Relative luminance data, collected via a fibre optic probe connected to a photo diode array, demonstrated the reason to be the low red colour seen by the panellists under FL and MH light sources. For the dark colour frankfurters, there was no difference in colour preference scores among the three illumination sources. Key words: Colour, fat, frankfurters, light, meat, sausage, sensory, spectra

Effect of three commercial light sources on acceptability of Salmon, Snapper and Sea Bass fillets

The effects of incandescent (INC), fluorescent (FL), and metal halide (MH) light sources on the acceptance of Salmon, Snapper and Sea Bass fillets were investigated. The color of the Salmon and Snapper was most preferred ( P<0.05) under INC light, as compared to FL and MH. Positive buying response was also significantly higher under INC as compared to FL and MH. Under INC light, salmon was described as dark and medium orange, but mainly light and medium orange under FL and MH. Relative luminance data, collected with a fiber optic probe connected to a photo diode array, showed that there was a low red and orange reflection from the fillets placed under FL and MH light sources. The Sea Bass was equally preferred under the three light sources due to its white/cream color.

DISPLAY LIGHT AND ACCEPTABILITY OF GREEN, RED AND YELLOW PEPPERS

The effects of incandescent (INC), fluorescent (FL), and metal halide (MH) light sources on the appearance of red, green, and yellow sweet bell peppers were investigated. The color of the red pepper was significantly preferred when presented under INC than under FL and MH lights. The term used by the panelists to describe the color of peppers under INC light was mainly bright red, but dark red under FL and MH. Relative luminance data, collected with a fiber optic probe connected to a photo diode array, demonstrated the reason to be the low red light output from the FL and MH sources, which resulted in a low visible red color. The color of the green pepper was more acceptable under INC than under MH. For the yellow pepper, there was no significant effect of the light source because all three light bulbs emit a strong yellow component.

Photodegradation and Laser Desorption Mass Spectrometry for the Characterization of Dyes Used in Red Pen Inks

Photodegradation and laser desorption mass spectrometry (LDMS) is a powerful combination of methods capable of characterizing dyes found in pen inks. Rhodamine dyes in pens that contain red ink were analyzed directly from paper (no extraction step is necessary). Inks exposed to incandescent light form photodegradation products (compounds with lower molecular weights than that of the intact dye) and in some instances, photoproducts (compounds with higher molecular weights than that of the intact dye). The degradation products and photoproducts can be detected with LDMS, and the results can be used for dye identification. Advantages include: (1) the instrumental analysis takes less than a minute; (2) sample preparation is minimal; (3) LDMS is a minimally destructive technique; (4) incandescent light sources are inexpensive, safe to use, and readily available; and (5) isomeric dyes can be distinguished.

Experimental characterization of rate-adaptive transmission and angle diversity reception techniques

Ambient light is the main impairment in indoor wireless optical communication systems for data rates up to several megabits per second. Its wide dynamic range, associated with the strong directivity of wireless optical signals, produce large variations on the received signal-to-noise ratio. This article discusses experimental results obtained from a testbed developed to compare different techniques for SNR improvement. The two techniques analyzed are rate-adaptive transmission, which introduces adaptive levels of redundancy in the transmitted signal to improve connectivity, and angle diversity reception, which exploits the inherent directionality of both signal and noise to improve the SNR at the receiver. Furthermore, systems employing both techniques simultaneously were also considered. The testbed replicated a typical indoor environment with both natural and artificial light, containing incandescent and fluorescent light sources. Both the SNR and the associated coverage areas were determined for all considered techniques. Our results show that the combined use of angle diversity based on maximal ratio combining and rate adaptation through the use of repetition coding achieves very good performance with only moderate complexity, allowing connectivity at all locations with data rates close to the maximum possible. In particular, with incandescent illumination and without angle diversity, the data rate had to be decreased down to 2 and 1 Mb/s in 25.9 and 7.7 percent of the room, area, respectively, whereas with maximal ratio combining a decrease to 2 Mb/s was only needed in 0.7 percent of the room area.

Polarized incandescent light emission from carbon nanotubes

Polarized light emission from multiwalled carbon nanotube (MWNT) bundles due to current heating is observed. The spectra of the emitted light fit well with the blackbody radiation distribution. And the emitted light is partially polarized with a degree of 0.33 along the axis of MWNT bundle, which is qualitatively explained in terms of one-dimensional structure of carbon nanotubes (CNTs). Negative temperature-dependent resistance is also observed, which is different from normal metal filaments. The MWNT bundles are very stable at high temperature in vacuum during light emitting, indicating that CNTs can be a good candidate as polarized incandescent light sources.

Effect of lighting on ground beef acceptability

The effects of incandescent (INC), cool-white fluorescent (FL), and metal halide (MH) light sources on the appearance of medium, lean, and extra lean ground beef meat were investigated. Meat color with INC illumination was preferred (P &lt; 0.05) over that with MH illumination for all meat types, and over FL illumination for extra-lean and medium meats. The majority of the panelists described the meat as red under INC lighting, but brown or dark red under FL and MH lighting. Relative luminance data, collected with a fiber optic probe connected to a photo diode array, demonstrated the reason to be a lack of redness in the FL and MH light sources. Key words: Acceptability, beef, color, hamburger, meat, spectra, sensory

Readers Illuminate Issues of Solid-State Lighting

Readers Illuminate Issues of Solid-State Lighting

THE RELATIONSHIP OF ILLUMINATION TO THE COLOR AND ACCEPTABILITY OF FERMENTED SAUSAGE

ABSTRACT The effects of incandescent (INC), fluorescent (FL), and metal halide (MH) light sources on the acceptance of Genoa salami, summer sausage and Cappola salami were investigated. The color of the Genoa salami was most preferred (P &lt; 0.05) under INC light, as compared to FL and MH. Positive buying response was also significantly higher (P &lt; 0.01) for this light product presented under INC. The major color used to describe the Genoa under INC light was pink, but brown under FL and MH. Relative luminance data, collected with a fiber optic probe connected to a photo diode array, demonstrated the reason to be a low red emission from the FL and MH light sources. The acceptability of the darker summer sausage and Cappola were not as affected by light source as the Genoa salami. The summer sausage was more preferred under INC compared to MH, but not under FL. The Cappola's color preference was not affected by any of the lights.

Effect of retail light sources on the appearance of processed turkey products

1. The effect of using incandescent (INC), fluorescent (FL) and metal halide (MH) light sources on panel preference of three turkey products was investigated. 2. For the bologna, smoked turkey and turkey breast, INC was the preferred light source. There was no significant difference in preference between the FL and MH light sources. 3. Relative luminance data, collected with a fibre optic probe connected to a photodiode array, demonstrated that the reason was a minimal red light output in the commercially used FL and MH light sources, which resulted in a lack of redness in the products.

Effect of illumination source on the appearance of fresh meat cuts

The effects of incandescent (INC), fluorescent (FL), and metal halide (MH) light sources on the appearance of fresh beef, pork and chicken meat were investigated. The color of all meats was more desired ( P<0.05) when presented under an INC light source. The color used to describe beef meat presented under INC light was red, but dark brown or dark red under FL and MH. Relative luminance data, collected with a fiber optic probe connected to a photo diode array, demonstrated the reason to be a lack of redness in the commonly used FL and MH light sources. This difference was more pronounced in dark red beef cuts than in lighter pork and chicken cuts.

Interaction of Color and Photointensity on Preening Behavior and Ingestion of Spray-Applied Biologics

Previous research has demonstrated that increased photointensity near the time of spray application can increase preening activity and ingestion of spray-applied material and can enhance establishment of a competitive exclusion culture. In the present study, inclusion of selected colors had a marked effect on preening activity, with fluorescein or forest green combined with fluorescein causing the greatest increase in preening under conditions of constant lighting (92 FC before, during and after spray). Minimal effects of constant incandescent (80 FC) vs. fluorescent light (80 FC) source were observed, regardless of the color used. While addition of color improved preening activity under constant lighting, no additional increase in preening activity was observed when coloring was added to the spray applied under conditions of increasing photointensity. These data indicate that coloring of spray solutions for application to neonatal chicks can improve preening activity under conditions of constant lighting. However, optimization of photointensity near the time of spray application negates the need for addition of coloring and, in fact, increases preening activity to levels not observed due to color addition to the spray solution under conditions of constant lighting.

Photodegradation of FeDTPA in Nutrient Solutions. I. Effects of Irradiance, Wavelength, and Temperature

Irradiation of FeDTPA-containing nutrient solutions by a fluorescent plus incandescent light source resulted in the loss of both Fe-chelate and soluble Fe, the formation of a precipitate that was composed mostly of Fe, and a rise in pH. The rate of Fe-chelate photodegradation in solution increased with irradiance intensity and with solution temperature under irradiation, but irradiance had the greater effect. Fe-chelates absorb in the blue and UV regions of the spectrum. Removal of these wavelengths with a spectral filter eliminated photodegradation. Chemical name used: ferric diethylenetriaminepentaacetic acid (FeDTPA).