ABSTRACT
Cr3+-doped Sr3Ga2Ge4O14:0.03Cr3+ (SGGO:0.03Cr3+) phosphor was synthesized via a high-temperature solid-phase method. Considering the tunable structure of SGGO, Ga3+ ions in the matrix were substituted with In3+ ions at a certain concentration. The tuned phosphor produced a red-shifted emission spectrum, with its luminescence intensity at 423 K maintained at 63% of that at room temperature; moreover, the internal quantum efficiency increased to 65.60%, and the external quantum efficiency correspondingly increased to 21.94%. On this basis, SGIGO:0.03Cr3+ was encapsulated into a pc-LED, which was applied in non-destructive testing (NDT) experiments, successfully realizing the recognition of water and anhydrous ethanol, proving its potential application in the field of NDT.
ABSTRACT
This report outlines a proposed method of packaging wide-angle (WA) mini-light-emitting diode (mini-LED) devices without optical lenses to create a highly efficient, ultrathin, flexible planar backlight for portable quantum dot light-emitting diode (QLED) displays. Since the luminous intensity curve for mini-LEDs generally recommends a beam angle of 120°, numerous LEDs are necessary to achieve a uniform surface light source for a QLED backlight. The light-guide layer and diffusion layer were packaged together on a chip surface to create WA mini-LEDs with a viewing angle of 180°. These chips were then combined with a quantum dot (QD) film and an optical film to create a high-efficiency, ultrathin, flexible planar light source with excellent color purity that can be used as a QLED display backlight. A 6 in (14.4 cm) light source was used as an experimental sample. When 1.44 W was supplied to the sample, the 3200-piece WA mini-LED with a flexible planar QLED display had a beam angle of 180° on the luminous intensity curve, a planar backlight thickness of 0.98 mm, a luminance of 10,322 nits, and a luminance uniformity of 92%.
ABSTRACT
A luminous intensity variation fluorescent probe (Probe 1) for the detection of ferric ion was developed. The quantitative range of Fe3+ content detected was 0-600 µM with the limit of detection at 0.76 µM. Furthermore, after 20 min of Fe3+ addition, the intensity of the luminescence of Probe 1 solution gradually decreased with increase in Fe3+ concentration. In addition, the B and G values of these images showed a linear relationship with Fe3+ concentration (0-500 µM). Probe 1 was successfully used for the rapid determination of Fe3+ concentration in real samples. This study demonstrates that Probe 1 is an excellent tool for the rapid determination of Fe3+ content in real samples using a smart phone without professional equipment.
Subject(s)
Fluorescent Dyes , Iron , Ferric Compounds , Ions , LuminescenceABSTRACT
Resumen: La señal de la amplitud en análisis de Potenciales Evocados Visuales (PEVs) es una variable que depende del tipo y posición de los electrodos, de la fuente, del estímulo y por consecuente, de la intensidad luminosa por lo que es fundamental reportarla para cada diseño experimental y así, garantizar su reproducibilidad. El objetivo de este trabajo es caracterizar una lámpara con 96 LEDs para la adquisición de PEVs en ratas. Se midió la iluminancia y la intensidad luminosa promedio en un sistema espacial XYZ de 8 cm3 aplicable a un sistema estereotáxico para la fijación de ratas. Se realizaron desplazamientos cada 2 cm en cada plano. Se observó que debido a la distribución geométrica de los LEDs la distribución de la iluminancia no sigue la ley del inverso cuadrado, ya que aumenta conforme la lámpara se aleja. Finalmente, se seleccionó una coordenada para la colocación del ojo de la rata empleando una intensidad luminosa promedio para la adquisición del PEV de 1.043 cd e iluminancia de 128.77 luxes a una distancia ojo-lámpara de 9 cm. Una vez caracterizada la intensidad luminosa y de acuerdo con los PEVs obtenidos, esta lámpara puede utilizarse para estudios PEV en ratas en investigaciones posteriores.
Abstract: Signal amplitude for recordings of Visual Evoked Potentials (VEPs) is a variable dependent on the type and position of the electrodes, the source, the stimulus and consequently the luminous intensity; therefore, it is relevant to report it to assure experimental reproducibility. The objective of this work is to characterize flash lamp with 96 LEDs in order to perform the acquisition of VEPs in rats. We measure the illuminance and mean light intensity on space system XYZ of 8 cm3 corresponding to a stereotaxic frame for rodents. Displacements were performed every 2 cm in each plane. Because of the geometric distribution of the LEDs in the EBNeuro lamp the spatial distribution of illuminance does not follow the law of the inverse square, because the illuminance increases as the lamp goes away. Finally a spatial coordinate was selected for the rat eye positioning were the mean luminous intensity was 1.043 cd and 128.77 luxes of illuminance at an eye-lamp distance of 9 cm. According to the obtained VEPs and spatial characterization this lamp can be used for acquire of recordings PEV in rats for further investigations.
ABSTRACT
Purpose: This study was designed to investigate the present conditions of illumination techniques in dental clinics in order to contribute improvement of operating environment. This study also aimed exploring qualitative and quantitative luminous intensity required for color temperature in dental clinic illumination, which was a critical part of esthetic dentistry. Materials and methods: A total of forty-eight local dental clinics were selected for sampling a) luminous intensity, and b) color temperature. The author measured the luminous intensity and the color temperature with lux meter and color meter respectively between 12pm and 2pm. The dental unit chair placed in the general operation positions were kept the distance 60 cm, then all dental units were measured three times and averaged. The author measured the luminous intensity and color temperature with both common dental operating light and then without operating light in different office environments. The study was conducted under three conditions: 1. artificial illumination in clear day light 2. artificial illumination in cloudy day light, and 3. artificial illumination alone. Results: The results obtained were as follows. 1. The average luminous intensity in dental clinic lighting was 425 lux which was not sufficient to produce the optimal shade of the patient's teeth. Furthermore, the average luminous intensity even in full operating lighting was 9532 lux which fell short of the required level of 10,000 lux. 2. The average color temperature of all dental clinics surveyed was 5169 K which met the optimal range. However, only 33.3% fell in the correct region between 5,000-5,500 K as 25% were over 5,500 K and 41.6% were below 5,000 K. As a result, 66.7% were under insufficient color temperature conditions. 3. The dental unit chair placed next to a window, hence exposure to natural lighting, had significantly higher luminous intensity and color temperature compared to the dental unit chair which didn't have a window or natural lighting. 4. The data analysis revealed that only 6.3% of the dental clinic were met the standard of the average luminous intensity and color temperature.
Subject(s)
Dental Clinics , Dentistry , Lighting , Statistics as Topic , ToothABSTRACT
NIST has recently established a detector-based luminous intensity unit (candela, cd), which is derived from the NIST absolute cryogenic radiometer. Subsequently, the luminous flux unit (lumen, lm) and the luminance unit (cd/m2) have been established based on the detector-based candela, and now all the NIST photometric units are tied to the cryogenic radiometer. The illuminance unit is realized and maintained on five standard photometers. The large dynamic range of the standard photometers eliminates the need for maintaining many working standard lamps of various wattages. The luminous intensities of lamps are determined from the illuminances measured with these photometers and the distances measured with a linear encoder system. Transfer photometers and illuminance meters are calibrated by direct comparison with the standard photometers with no distance measurements involved. The luminous flux unit is realized using an absolute integrating sphere method newly developed at NIST. The luminance unit is realized on an integrating sphere source, which is used for calibration of other luminance sources and luminance meters. These detector-based methods have made it possible to reduce the uncertainties of photometric calibrations and to provide more varieties of photometric calibration services at NIST.
ABSTRACT
The Système International des Unités (SI) base unit for photometry, the candela, has been realized by using absolute detectors rather than absolute sources. This change in method permits luminous intensity calibrations of standard lamps to be carried out with a relative expanded uncertainty (coverage factor k = 2, and thus a 2 standard deviation estimate) of 0.46 %, almost a factor-of-two improvement. A group of eight reference photometers has been constructed with silicon photodiodes, matched with filters to mimic the spectral luminous efficiency function for photopic vision. The wide dynamic range of the photometers aid in their calibration. The components of the photometers were carefully measured and selected to reduce the sources of error and to provide baseline data for aging studies. Periodic remeasurement of the photometers indicate that a yearly recalibration is required. The design, characterization, calibration, evaluation, and application of the photometers are discussed.
ABSTRACT
A bilateral intercomparison of photometric units between NIST, USA and PTB, Germany has been conducted to update the knowledge of the relationship between the photometric units disseminated in each country. The luminous intensity unit (cd) and the luminous flux unit (lm) maintained at both laboratories are compared by circulating transfer standard lamps. Also, the photometric responsivity sv is compared by circulating a V(λ)-corrected detector with a built-in current-to-voltage converter. The results show that the difference of luminous intensity unit between NIST and PTB, (PTB-NIST)/NIST, is 0.2 % with a relative expanded uncertainty (coverage factor k = 2) of 0.24 %. The difference is reduced significantly from that at the 1985 CCPR intercomparison (0.9 %). The difference in luminous flux unit, (PTB - NIST)/NIST, is found to be 1.5 % with a relative expanded uncertainty (coverage factor k =2) of 0.15 %. The difference remained nearly the same as that at the 1985 intercomparison (1.6 %). These results agree with what is predicted from the history of maintaining the units at each laboratory.
