Small Light Source Research Articles

Determining appropriate ambient lighting levels in Radiology reporting rooms

Determining appropriate ambient lighting levels in Radiology reporting rooms

The Analysis of Institutional Factors for Gain of EDFA

Small signal gain of fiber amplifier has been measurement using a small signal broadband light source of simple and more accurate. And through the numerical simulation for test condition and experimental results of this method are discussed. The factors influencing of the erbium-doped fiber amplifier gain has been simulation and analysis, and effect of fiber length on the gain of the test. A new method is proposed for measuring optical fiber amplifier gain spectrum.

Illumination for Process Observation in Laser Material Processing

Abstract Process control for laser-material-processing requires access to characteristic features which qualify the operating-point of the process. For laser-based manufacturing-processes, this can either be achieved by detecting the emission of the process or by detecting geometric properties of the process-workpiece interaction. Such illumination is usually provided by lasers emitting in the near-infrared. Inherent properties like coherence of these sources and complex optical systems prohibit a wide adoption. The technological advance in sources such as led's has the potential to deploy small light sources directly to the processing heads but bears new problems in light-ray-delivery, emitter-protection against secondary radiation and cooling. From a scientific point of view, the properties of illumination sources are compared with a special focus on the specific requirements of process observation.

Bothering Myself

Bothering Myself

WEEE and portable batteries in residual household waste: Quantification and characterisation of misplaced waste

A total of 26.1Mg of residual waste from 3129 households in 12 Danish municipalities was analysed and revealed that 89.6kg of Waste Electrical and Electronic Equipment (WEEE), 11kg of batteries, 2.2kg of toners and 16kg of cables had been wrongfully discarded. This corresponds to a Danish household discarding 29g of WEEE (7 items per year), 4g of batteries (9 batteries per year), 1g of toners and 7g of unidentifiable cables on average per week, constituting 0.34% (w/w), 0.04% (w/w), 0.01% (w/w) and 0.09% (w/w), respectively, of residual waste. The study also found that misplaced WEEE and batteries in the residual waste constituted 16% and 39%, respectively, of what is being collected properly through the dedicated special waste collection schemes. This shows that a large amount of batteries are being discarded with the residual waste, whereas WEEE seems to be collected relatively successfully through the dedicated special waste collection schemes. Characterisation of the misplaced batteries showed that 20% (w/w) of the discarded batteries were discarded as part of WEEE (built-in). Primarily alkaline batteries, carbon zinc batteries and alkaline button cell batteries were found to be discarded with the residual household waste. Characterisation of WEEE showed that primarily small WEEE (WEEE directive categories 2, 5a, 6, 7 and 9) and light sources (WEEE directive category 5b) were misplaced. Electric tooth brushes, watches, clocks, headphones, flashlights, bicycle lights, and cables were items most frequently found. It is recommended that these findings are taken into account when designing new or improving existing special waste collection schemes. Improving the collection of WEEE is also recommended as one way to also improve the collection of batteries due to the large fraction of batteries found as built-in. The findings in this study were comparable to other western European studies, suggesting that the recommendations made in this study could apply to other western European countries as well.

47.2: Novel Measurement Method of Bright‐Light Contrast Ratio Based on Binocular Vision

AbstractIt is well known that ambient light reduces the contrast ratio. However binocular human perception is often better than expected by monocular measurements. We evaluated this by subjects and adapted the measurement set‐up to binocular vision. Typical mobile displays were examined and we verified the binocular visual perception of small specular light sources.

Home Noninvasive Ventilation

During the first 5-month period of this 10-month study, arterial cannulations were performed using the standard technique based on palpation of pulsation or anatomic landmarks in 38 children. During the second 5 months, cannulations were performed with a NIRVIS in 29 children. The NIRVIS has a small NIR light source to transilluminate the puncture site. The light is projected on a display located above the puncture site, with blood vessels then visible as dark lines on a white background of the tissue. Patients were under general inhalation anesthesia with sevoflurane. The radial or ulnar artery at the wrist was the preferred site for the cannulations, performed with an over-the-needle technique (Abbocath 22-gauge or 24-gauge; Abbott, Chicago, Ill). If cannulation did not succeed at the wrist, the brachial or femoral artery was cannulated without the use of the NIRVIS, which is unable to visualize either of those arteries. The primary outcome measure was the total time to successful cannulation. Secondary outcomes were the time to the first flashback of blood, indicating that the artery was penetrated, and success at first attempt and number of punctures. Patient characteristics were comparable between the 2 groups. In 32 of the 39 patients in the NIRVIS group, the arteries were seen with the device. The median time to successful cannulation was 547 seconds without, and 464 seconds with, the use of the NIRVIS, not a statistically significant difference. The median times to the first flashback of blood were 171 and 219 seconds, respectively. Adjusting for confounders (weight for age, age, complicating factors, gender, anesthesiologist, mean arterial pressure, use of catecholamines) did not alter the results but did show that age and weight for age were predictors for a shorter time to successful cannulation and shorter time to first flashback of blood. The first attempt was successful in 7 of 38 patients without the NIRVIS and in 12 of 39 with the NIRVIS. This was not a statistically significant difference, however, after adjusting for confounders. Age was a predictor of success at first attempt with an odds ratio of 1.12. Three punctures were needed with the NIRVIS compared with 6 without the device. The success rate for cannulations in the wrist was 62% for the NIRVIS group compared with 50% for the non-NIRVIS group. This meant that the other 15 and 19 patients, respectively, required femoral or brachial lines. Although the use of NIRVIS did not substantially improve time and success rate of arterial cannulation in young children, it did offer advantages for success at first attempt and number of punctures. The results indicate that the insertion of the cannula, not localizing the artery, is the primary difficulty in performing arterial cannulation in small children.

Photometric characterisation of small sources with high dynamic range illuminance mapping

In this paper a system for obtaining the luminous intensity distribution of a small light source, based on high dynamic range imaging, is described. The system uses a dark room, a lambertian screen and a video-luminance-meter mounted on a workbench. The luminous intensity distribution of the light source is derived from the illuminance map on the screen by applying the photometric inverse law. The geometry of the system is presented and the measurements’ uncertainties are estimated. Finally, an application to a LED source is presented.

Simulation of virtual natural lighting solutions with a simplified view

Daylight is limited in time and space. In situations where daylight is insufficiently available, virtual natural lighting solutions (VNLS), which are systems that artificially provide lighting and view comparable to those of real windows and skylights, can be promising. VNLS can turn currently unused floor space into space with daylight qualities. The space-gaining potential of VNLS in buildings can be predicted using computational building performance simulation. This paper describes the approach of modelling VNLS with a simplified view, using the Radiance tool to evaluate the lighting performance in a reference office. The VNLS are modelled as arrays of small light sources resembling the sky, the horizon and the ground. The simulation results show that VNLS with wide beam angles generally offer a better uniformity and a larger percentage of sufficiently lit workplane area compared to those obtained with real windows under overcast sky conditions, while the discomfort glare remains comparable to that received from real windows.

Validation of a novel high‐intensity LED light source for skin phototesting at 365 nm

The gold standard for investigation of patients with suspected photosensitivity involves phototesting on non-exposed skin with an irradiation monochromator (IM). However, this device is bulky, expensive and only available at a small number of specialised photodermatology units. We have developed a small handheld high output monochromatic light source for phototesting to UVA at 365 nm using light-emitting diodes (LEDs). A UNO light engine (Enfis, Swansea, UK) at 365 nm was used to develop a handheld intense source. Seventy-seven normal healthy volunteers were phototested on the lower back with the LED source and with an IM at 365 nm. Minimal erythema dose (MED) at 24 h was assessed visually and by a diffuse reflectance erythemameter. In 77 volunteers, MED levels for the two sources agreed in 66 out of 77 cases (85.7%). In a further 10 out of 77 patients, the measured MED elicited by the LED source was 1 dose level higher than the monochromator MED. A high-intensity portable and low cost LED phototesting device was developed. The results confirm that phototesting to UVA at 365 nm using this LED light source compares favourably to monochromator light testing at this wavelength.

THE INSTALLATION AND EVALUATION OF LOW ILLUMINANCE STREET LIGHTING WHICH DISTRIBUTES SMALL INTENSITY LIGHT SOURCES

This paper reports the outline of a new street lighting environment which distributed small intensity light sources. The amounts of luminous flux and consumption energy have got smaller than the previous street lighting, and the illuminance level on the street has also become low. The visibility around the street has improved by having installed lights in the vacant lots contiguous to the street. However, the possibility of danger and sense of insecurity originating in darkness were pointed out by the pedestrian. It was considered to be necessary to examine the negative factors about the darkness from different directions in the long term.

Maxillary midline diastema among Saudi schoolchildren in Riyadh: prevalence and some related etiological factors

The aim of this study is to investigate the maxillary midline diastema in Saudi schoolchildren in Riyadh; particularly prevalence and some likely related etiological factors with regard to gender and age. The present epidemiologic study was undertaken in intermediate schools of Riyadh City. A total of 1,825 Saudi schoolchildren (1007 boys and 818 girls) aged 12 to 16 years were randomly selected. Clinical examination was carried out in the schools within the students’ classrooms by two experienced examiners using simple plain mouth mirror, small light source and stainless steel ruler. Students with a history of orthodontic treatment or prosthodontic restorations in the upper anterior teeth and periodontal disease were not included in the sample. An especially composed chart was used to record demographic dataand inter arch parameters. All data were analyzed using SPSS program and simple descriptive statistics with regard to boys and girls. Results revealed the prevalence of maxillary midline diastema was 394 (22%) out of 1825 students examined. A similar figure, though slightly greater prevalence of maxillary midline diastema in boys (22%) than in girls (21%). The highest prevalence was observed in 13 years age group (7.7%). The width of maxillary midline diastema ranged between 1-2 millimeters demonstrated (79.2%) of total sample, greater in boys (91%) than girls (64.4%), and (100%) in 16 years age group. The maxillary midline diastema width of 3-4 millimeters occurred more in girls (35%) than boys (9%), and in 12 years age group (35.5%) than other age groups with decrease up to 16 years of age. Among the observed etiological factors in both sexes and different age groups, spacing in anterior region (35.5%) was the most frequent etiological factor associated with maxillary midline diastema. Followed by increased ovejet (15.7%), missing tooth (11%), while the frequency of deep bite and anterior open bite was 6.3% and 5.8% respectively. It was concluded that maxillary midline diastema is a common occurrence in Saudi children associated with multifactorial etiology. Consideration of etiological factors and individual treatment planning are essential in the proper management of maxillary midline diastema.

Electrical injection, continuous wave operation of subwavelength-metallic-cavity lasers at 260 K

We report continuous wave lasing operation at T=260 K of subwavelength-metallic-cavities with semiconductor core encapsulated in silver under electric injection. The physical cavity volumes of the two lasers presented are 0.96λ3 (λ=1563.4 nm) and 0.78λ3 (λ=1488.7 nm), respectively. Longitudinal modes observed in one of lasers correspond to the Fabry–Perot cavity in the length direction. Such record high temperature operation of a subwavelength laser is of great importance for the development of small light sources in future integrated photonic circuits and other on-chip applications.

Monitoring the microcirculation in the critically ill patient: reflectance spectroscopy

Dear Editor, I read with great interest and pleasure the excellent overview of the most common methods currently used to monitor the microcirculation by De Backer and colleagues [1]. The expertise of this group of authors with most of the methods described in their review of innumerable original publications was clearly evident. However, the section on reflectance spectroscopy is rather short, suggesting that they may lack in-depth practical experience with that specific method. In particular, the last sentence on recent developments in the technique is incorrect and needs to be explained more specifically. The first device using reflectance spectroscopy (EMPHO) was limited to perpendicular probes for mucosa measurements and was based on spectrophotometry only. Nevertheless, it has been used in numerous experimental and clinical studies performed by our group for assessing the effects of various factors and agents, such as positive airway pressure, intraabdominal pressure, hypercapnia, cardiopulmonary bypass, vasoactive drugs and anaesthetics, on the splanchnic microcirculation [for references, see the Electronic Supplementary Material (ESM)]. The latest development using reflectance spectroscopy is incorporated in the O2C (oxygen to see) device (Lea, Giessen, Germany). The technology of the O2C device is based on two physical principles: reflection spectroscopy and the laser Doppler technique. Compared to the EMPHO device, the O2C instrument integrates both techniques in a much smaller device because the rotating filter wheel has been replaced by a CCD-spectrometer and the xenon high-pressure lamp by a small light source optimised for fibre optics. Specific probes are used to introduce white light (wavelengths 500–800 nm) and laser light (wavelength 830 nm) simultaneously into the tissue. A part of the light spectrum is absorbed when the white light interacts with the erythrocytes, and this absorbed portion assumes the colour of the haemoglobin as a measure of its oxygen saturation. The laser light experiences a frequency displacement due to the moving erythrocytes (the so-called Doppler Shift), and this displacement is a measure of their velocity. The sum of all erythrocytes and their velocity is a measure of blood flow (volume flow) in the complex network of capillaries. With this device the following parameters can be measured simultaneously in tissue: the oxygen saturation of haemoglobin (μHbO2) at the venous end of the capillaries (the so-called “last meadow”); the regional amount of haemoglobin (rHb) in the micro-blood vessels as a measure of its blood volume and for capillary density; the velocity of the blood in microcirculation; the flow of blood in the microcirculation. The main advantage of this technology when assessing microvascular blood flow is that this combination of parameters allows the determination of regional oxygen consumption (rVO2) in the tissue as a direct measure of tissue viability. The metabolism may be a more important parameter than the heterogeneity of perfusion, which is considered to be a key to monitor sepsis (for details, see ESM). The method has been used clinically to assess the microvascular response in patients with septic shock [2], to monitor the effects of extreme anaemia [3] or flap viability [4] and to predict wound healing in burn injury [5]. In conclusion, the combination of reflection spectroscopy and laser Doppler (O2C) may offer a useful enlargement of the diagnostic tools available to the clinician for assessing microvascular blood flow and tissue oxygen consumption.

Testing the performance of a novel spectral reflectance sensor, built with light emitting diodes (LEDs), to monitor ecosystem metabolism, structure and function

We developed and tested the use of light emitting diodes (LEDs) to monitor vegetation reflectance in narrow spectral bands as a tool suitable for quantifying and monitoring ecosystem structure, function and metabolism. LEDs are appealing because they are inexpensive, small and reliable light sources that, when used in reverse mode, can measure spectrally selective radiation. We selected LEDs in red and near-infrared wavebands as they are used to calculate the normalized difference vegetation index (NDVI). The lab experiments revealed that the LEDs showed linear relation with a hyper-spectral spectroradiometer ( R 2 > 0.94 and 0.99 for red and NIR, respectively) and marginal sensitivity to temperature. To test the efficacy of this novel sensor, we measured spectral reflectance with LEDs over an annual grassland in California over 3.5 years. The LED-sensor captured daily to interannual variation of the spectral reflectance at the two bands with reliable and stable performance. The spectral reflectance in the two bands and NDVI proved to be useful to identify the leaf-on and leaf-off dates (mean bias errors of 5.3 and 4.2 days, respectively) and to estimate canopy photosynthesis ( R 2 = 0.91). We suggest that this novel instrument can monitor other structural and functional (e.g. leaf area index, leaf nitrogen) variables by employing LEDs that have other specific wavelengths bands. Considering that off-the-shelf LEDs cover a wide range of wavebands from the ultraviolet to near-infrared regions, we believe that the research community could explore a range of similar instruments across a range of bands for a variety of ecological applications.

Cosine lobes for interactive direct lighting in dynamic scenes

Cosine functions have been widely used for representing Bidirectional Reflection Distribution Functions (BRDF) such as Lambert, Phong and Lafortune models. They are well suited to represent both high and low frequency signals. However, they are difficult to use with visibility and incident radiance. In most systems, the rendering equation terms are thus estimated using various methods. Several interactive rendering systems rather rely on the projection of each term onto orthonormal basis functions such as spherical harmonics or wavelets. These methods are easier to handle since the integration becomes a dot product. However, these functions are also subject to several drawbacks. For instance the number of coefficients is high for the representation of high frequency phenomena; the pre-computation time required for projecting each term of the rendering equation cannot be neglected. This paper demonstrates that cosine lobes can be generalized to visibility and incoming radiance with several advantages. First, cosine lobes do not form an orthonormal basis of functions and the number of parameters remains naturally adapted to the signal. This is very interesting for complex and high frequency functions: glossy BRDF or small light sources for instance. We also use this property for reducing the number of parameters as the computation goes along. Second, Lambert, Phong and Lafortune BRDF models are already used in many rendering systems. Since they already rely on this representation, no transformation into other types of model is necessary. This paper shows how it is possible to rapidly integrate the product of cosine lobes. As a demonstration of our methodology, we propose an interactive rendering system for direct lighting, including soft shadows and spatially varying materials.

Diffractive phase-shift lithography photomask operating in proximity printing mode

A phase shift proximity printing lithographic mask is designed, manufactured and tested. Its design is based on a Fresnel computer-generated hologram, employing the scalar diffraction theory. The obtained amplitude and phase distributions were mapped into discrete levels. In addition, a coding scheme using sub-cells structure was employed in order to increase the number of discrete levels, thus increasing the degree of freedom in the resulting mask. The mask is fabricated on a fused silica substrate and an amorphous hydrogenated carbon (a:C-H) thin film which act as amplitude modulation agent. The lithographic image is projected onto a resist coated silicon wafer, placed at a distance of 50 microm behind the mask. The results show a improvement of the achieved resolution--linewidth as good as 1.5 microm--what is impossible to obtain with traditional binary masks in proximity printing mode. Such achieved dimensions can be used in the fabrication of MEMS and MOEMS devices. These results are obtained with a UV laser but also with a small arc lamp light source exploring the partial coherence of this source.

Near-Field Scanning Nanophotonic Microscopy—Breaking the Diffraction Limit Using Integrated Nano Light-Emitting Probe Tip

We introduce a novel scanning ldquonanophotonicrdquo microscope through monolithic integration of a nanoscale LED (Nano-LED) on a silicon cantilever. We review two recent trends of incorporating miniature light sources on the scanning probes for near-field scanning optical microscopy: one is to attach fluorephores at the tip to define a small light source, while the other is to integrate an LED and a nanometer aperture into scanning probes, based on silicon microfabrication techniques. The creation of Nano-LED combines the advantages of previous two approaches: no external sources are required and the reduction of the light source size directly leads to resolution improvement. Two types of Nano-LEDs have been successfully demonstrated utilizing nanofabrication and microelectromechanical systems technologies: 1) formation of thin silicon dioxide light-emitting layer between heavily doped p + and n+ silicon layers created by a focused ion beam and 2) electrostatic trapping and excitation of CdSe/ZnS core-shell nanoparticles in a nanogap. We employed these probes into a standard near-field scanning and excitation setup. The probe successfully measured optical as well as topographic images of chromium test patterns with imaging resolutions of 400 and 50 nm, respectively. In addition, the directional resolution dependence of the acquired images suggests the size and shape of the light source. To our knowledge, these results are probably the first successful near-field images directly measured by such tip-embedded light sources. With the potential emission capability from near UV to IR and additional mass producibility, the nanophotonic microscope presents exciting opportunities in near-field optics, integrated circuit technology, nanomanufacturing and molecular imaging, and sensing in biomedicine.

LED-FISH: Fluorescence microscopy based on light emitting diodes for the molecular analysis of Her-2/neu oncogene amplification

Light emitting diodes (LED), which are available as small monochromatic light sources with characteristic features such as maximum illumination power combined with minimum energy consumption and extremely long lifespan have already proved as a highly potential low-cost alternative for specific diagnostic applications in clinical medicine such as tuberculosis fluorescence microscopy. Likewise, the most reliable evaluation of Her-2/neu (c-erbB2) gene amplification, which has been established in the last few years for routine diagnosis in clinical pathology as determinant towards Herceptin-based treatment of patients with breast cancer, is based on fluorescence in situ hybridization (FISH) and corresponding high priced fluorescence equipment. In order to test the possibility to utilize the advantages of low-cost LED technology on FISH analysis of c-erbB2 gene expression for routine diagnostic purposes, the applicability of a standard bright field Carl Zeiss Axiostar Plus microscope equipped with a Fraen AFTER* LED Fluorescence Microscope Kit for the detection of Her-2/neu gene signals was compared to an advanced Nikon Eclipse 80i fluorescence microscope in combination with a conventional 100W mercury vapor lamp. Both microscopes were fitted with the same Quicam FAST CCD digital camera to unequivocally compare the quality of the captured images. C-erbB2 gene expression was analyzed in 30 different human tissue samples of primary invasive breast cancer, following formalin fixation and subsequent paraffin-embedding. The Her2/neu gene signals (green) were identifiable in the tumor cells in all cases and images of equal quality were captured under almost identical conditions by 480 nm (blue) LED module equipped standard Axiostar microscope as compared to conventional fluorescence microscopy. In this first attempt, these monochromatic LED elements proved in principle to be suitable for the detection of Her-2/neu gene expression by FISH. Thus, our own experiences emphasize the high potential of this technology to provide a serious alternative to conventional fluorescence microscopy in routine pathology; representing a sustainable technological progress, this low-cost technology will clearly give direction also to the growing field of molecular pathology.* AFTER = Amplified Fluorescence by transmitted Excitation of Radiation

Directional blue light irradiation triggers epidermal cell elongation of abaxial side resulting in inhibition of leaf epinasty in geranium under red light condition

Plant morphogenesis is strongly affected by light quality. We evaluated the effects of localized blue light irradiation from light-emitting diodes (LED) on the leaf shape of geranium plants, which show epinasty under red light conditions. Geranium ( Pelargonium zonale Ait.) plants with five or six true leaves were transplanted into a growth chamber containing a metal halide lamp (MH) or a red LED panel (R-LED) that irradiated light at an intensity of 100 μmol m −2 s −1. The fifth true leaves were then subjected to localized irradiation from small LED light sources. Under localized irradiation of blue light at a 50 μmol m −2 s −1 intensity level, the leaf epinasty index, was 20% lower than under localized red irradiation. The extent of the inhibition of leaf epinasty by blue LED irradiation depended on the light intensity. Blue light irradiation to the abaxial sides of leaves did not inhibit leaf epinasty under red irradiation. In response to blue light irradiation to the adaxial side of the fifth true leaf, the leaf angle reached 225° by the end of the experiment, which was larger than the angle reached under red irradiation. In fifth true leaves treated with localized blue irradiation for 6 h during the daytime, the leaf epinasty level was higher than with blue light irradiation for 12 h. The length of epidermal cells of the abaxial sides irradiated with blue light was 7–13% longer than under red irradiation in the absence of blue irradiation. These results suggest that in geranium, leaf epinasty is controlled by cell elongation in the abaxial epidermis triggered by blue light irradiation of the adaxial side of the leaf.