scholarly journals Characteristic parameters of photonic nanojets of single dielectric microspheres illuminated by focused broadband radiation

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Amartya Mandal ◽  
Pragya Tiwari ◽  
Paul K. Upputuri ◽  
Venkata R. Dantham
Keyword(s):  
Light Emitting Diode ◽  
Surrounding Medium ◽  
Incident Beam ◽  
Monochromatic Radiation ◽  
Interference Microscopy ◽  
Halogen Lamp ◽  
Characteristic Parameters ◽  
Broadband Radiation ◽  
Photonic Nanojets ◽  
Polychromatic Radiation

AbstractHerein, we report the theoretical investigation on the photonic nanojets (PNJs) of single dielectric microspheres illuminated by focused broadband radiation (polychromatic light) from a Halogen lamp, supercontinuum source, light-emitting diode, and Hg arc lamp. The role of incident beam waist, refractive index of the surrounding medium, and radius of the microsphere on the characteristic parameters such as the electric field intensity enhancement, effective width, and length of the PNJ is studied. Interestingly, the characteristic parameters of the PNJs of solid microspheres obtained for the above-mentioned broadband radiation sources are found close to those observed for the focused monochromatic radiation of wavelengths which are near to the central wavelengths of the sources. Moreover, the characteristic parameters of PNJs of the core–shell microspheres of different thicknesses (t) illuminated by polychromatic radiation from most commonly used sources such as Halogen and Hg arc lamps are studied. For each t value, a suitable wavelength of monochromatic radiation has been found to generate the PNJ with characteristic parameters which are close to those obtained in the case of polychromatic radiation. We believe that the analytical theory and the theoretical simulations reported here would be useful for researchers who work in the fields such as PNJ assisted photoacoustic spectroscopy, white light nanoscopy, low-coherence phase-shifting interference microscopy, and Mirau interferometry.

scholarly journals Clinical Evaluation of Bracket Bonding Using Two Different Polymerization Sources

2008 ◽  
Vol 78 (5) ◽  
pp. 922-925 ◽  
Author(s):  
Nikolaos S. Koupis ◽  
Theodore Eliades ◽  
Athanasios E. Athanasiou
Keyword(s):  
Failure Rate ◽  
Orthodontic Treatment ◽  
Light Emitting Diode ◽  
Rank Test ◽  
Dental Arch ◽  
Halogen Lamp ◽  
Failure Rates ◽  
Bond Failure ◽  
Significant Difference ◽  
The Right

Abstract Objective: To comparatively assess clinical failure rate of brackets cured with two different photopolymerization sources after nine months of orthodontic treatment. Materials and Methods: The sample of this study comprised 30 patients who received comprehensive orthodontic treatment by means of fixed appliances. Using the same adhesive, 600 stainless steel brackets were directly bonded and light cured for 10 seconds with the light-emitting diode (LED) lamp or for 20 seconds with the conventional halogen lamp. A split-mouth design randomly alternated from patient to patient was applied. Failure rates were recorded for nine months and analyzed with Pearson χ2 test, and log-rank test at α = .05 level of significance. Results: The overall failure rate recorded with the halogen unit (3.33%) was not significantly different from the failure rate for the LED lamp (5.00%). Significantly more failures were found in boys compared with girls, in the mandibular dental arch compared with the maxillary arch, and in posterior segments compared with anterior segments. However, no significant difference was found between the right and left segments. Conclusion: Both light-curing units showed sufficiently low bond failure rates. LED curing units are an advantageous alternative to conventional halogen sources in orthodontics because they enable a reduced chair-time bonding procedure without significantly affecting bond failure rate.

scholarly journals Design of Elliptic Reflective LED Surgical Shadowless Lamps Using Mathematical Optical Tracing Algorithms

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Cheng-Tang Pan ◽  
Yi-Chian Chen ◽  
Tsung-Lin Yang ◽  
Po-Hsun Lin ◽  
Po-Hung Lin ◽  
...  
Keyword(s):  
Elliptic Curves ◽  
Light Field ◽  
Light Emitting Diode ◽  
Heat Radiation ◽  
Halogen Lamp ◽  
Optical Efficiency ◽  
Light Emitting ◽  
Light Rays ◽  
Mathematical Algorithms ◽  
Freeform Lens

Traditional surgical shadowless halogen lamps are generally designed as projection type with many light bulbs, which can produce not only mercury pollution but also heat radiation that are serious problems to patient. The study utilized Runge-Kutta methods and mathematical algorithms to design and optimize the freeform lens. The LED (light-emitting diode) was adopted to replace the traditional halogen lamp. A uniform lens was designed and fabricated based on the energy conservation. At first, the light field of LED is concentrated through the freeform lens to improve the optical efficiency. Second, the three-shell elliptic curves are applied to the reflective surgical shadowless lamps, where only few LED chips are needed. Light rays emitting from different directions to the target plane can achieve the goal of shadowless. In this study, the LED’s luminance flux is 1,895 lm. The shadow dilution on the target plane is 54%.Ec(central illuminance) is 114,900 lux, and thed50/d10is 57% which is higher than the regulation by 7%, whereas the power consumption is only 20 W. The energy of reflective surgical shadowless lamps can save more than 50%, compared with the traditional projective one.

scholarly journals Artifact removal in the contour areas of SAXS-CT images by Tikhonov-L1 minimization

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Hiroki Ogawa ◽  
Shunsuke Ono ◽  
Yuki Watanabe ◽  
Yukihiro Nishikawa ◽  
Shotaro Nishitsuji ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Incident Beam ◽  
Ct Image ◽  
Characteristic Parameters ◽  
Artifact Removal ◽  
L1 Minimization ◽  
X Ray ◽  
Nanoscale Structures ◽  
X Ray Scattering ◽  
Surface Length

Small-angle X-ray scattering (SAXS) coupled with computed tomography (CT), denoted SAXS-CT, has enabled the spatial distribution of the characteristic parameters (e.g. size, shape, surface, length) of nanoscale structures inside samples to be visualized. In this work, a new scheme with Tikhonov regularization was developed to remove the effects of artifacts caused by streak scattering originating from the reflection of the incident beam in the contour regions of the sample. The noise due to streak scattering was successfully removed from the sinogram image and hence the CT image could be reconstructed free from artifacts in the contour regions.

scholarly journals Microhardness of resin-based materials polymerized with LED and halogen curing units

2005 ◽  
Vol 16 (2) ◽  
pp. 98-102 ◽  
Author(s):  
Daniela Francisca Gigo Cefaly ◽  
Giovano Augusto de Oliveira Ferrarezi ◽  
Celiane Mary Carneiro Tapety ◽  
José Roberto Pereira Lauris ◽  
Maria Fidela de Lima Navarro
Keyword(s):  
Statistical Analysis ◽  
Light Emitting Diode ◽  
Surface Hardness ◽  
Bottom Surface ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Led Light ◽  
Significant Difference ◽  
Light Curing ◽  
Curing Light

The purpose of this study was to evaluate the microhardness of resin-based materials polymerized with a LED (light-emitting diode) light-curing unit (LCU) and a halogen LCU. Twenty cylindrical specimens (3.0 mm in diameter and 2.0 mm high) were prepared for each tested material (Z100, Definite and Dyract). Specimens were light-cured with two LCUs (Ultraled and Curing Light 2500) for either 40 or 60 s on their top surfaces. Hardness was measured on top and bottom surfaces of each specimen. Statistical analysis was done by ANOVA and Tukey's test (p<0.05). There was no significant difference in hardness between LED LCU and halogen LCU for Z100 and Dyract on top surface. Conversely, lower hardness was recorded when Definite was light-cured with the LED LCU than with the halogen lamp. On bottom surface, hardness was significantly lower for all materials light-cured with LED LCU. Z100 was harder than Dyract and Definite regardless of the light curing unit. There was no significant difference in hardness between the exposure times on top surface. Higher hardness was obtained when the materials were light-cured for 60 s on bottom surface. The tested LED was not able to produce the same microhardness of resin-based materials as the halogen LCU.

scholarly journals Evaluation of Different Light-Curing Units—Light-Emitting Diodes and Quartz–Tungsten–Halogen-Based Light-Curing Units in Polymerization of Posterior Composite: An In Vitro Study

2018 ◽  
Vol 6 (02/03) ◽  
pp. 060-064
Author(s):  
R. Bansal ◽  
M. Bansal ◽  
S. Walia ◽  
C. Gupta ◽  
L. Bansal ◽  
...  
Keyword(s):  
Composite Resin ◽  
Light Emitting Diode ◽  
In Vitro Study ◽  
Hardness Test ◽  
Acrylic Resin ◽  
Halogen Lamp ◽  
Light Emitting ◽  
Quartz Tungsten Halogen ◽  
Light Curing

Abstract Objective To assess the adequacy of various light-curing units to polymerize the posterior composite resin. Materials and Methods Specimens were prepared by placing a single increment of posterior composite resin in split cylindrical metallic mold of dimension (6.0 mm in diameter and 5 mm in depth). Polymerization was done by utilizing one quartz-tungsten-halogen and three light-emitting diode light-curing units of different powers. The specimens of composite resin were then mounted on metallic molds utilizing autopolymerizing acrylic resin. After polishing, the complete setting of composite resin material was analyzed using Vickers hardness test. Results Showed in each group, hardness reduced as we moved from upper to lower surface of composite resin. Furthermore, hardness increased as intensity of light was increased. The maximum hardness was detected when light-emitting diode light-curing unit having intensity of 1,250 mW/cm2 was utilized and least hardness was detected when halogen lamp having intensity 418 mW/cm2 was utilized and results were found to be highly significant (p < 0.01). Conclusion It was concluded that increased top and bottom hardness can be accomplished by utilizing the light-curing unit of high intensity.

scholarly journals A Multi-Analytical Approach for Studying the Effect of New LED Lighting Systems on Modern Paints: Chemical Stability Investigations

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4441
Author(s):  
Valentina Pintus ◽  
Ferenc Szabó ◽  
Dávid Noel Tóth ◽  
Karin Wieland ◽  
Péter Csuti ◽  
...  
Keyword(s):  
Chemical Stability ◽  
Light Emitting Diode ◽  
Linseed Oil ◽  
Principal Component ◽  
Gas Chromatography Mass Spectrometry ◽  
Halogen Lamp ◽  
Lighting System ◽  
Pyrolysis Gas ◽  
Led Lighting ◽  
Lighting Systems

This study aims to investigate the chemical stability of some modern paint samples exposed to a new Light Emitting Diode (LED)-lighting system and a halogen lamp by using micro-attenuated total reflectance of Fourier transform infrared spectroscopy (µ-ATR-FTIR), µ-Raman, pyrolysis—gas chromatography/mass spectrometry (Py-GC/MS), and thermally assisted hydrolysis and methylation of GC/MS (THM-GC/MS). Those investigations were performed before and after the exposure of the samples to lightings for 1250, 2400, 3300, and 5000 h. The results obtained with µ-Raman spectroscopy show the high stability of the selected inorganic pigments after the exposure to the lighting systems; while similar to the UV/Vis/NIR results reported in a previous study, µ-ATR-FTIR and THM-GC/MS results evidence greater chemical changes occurring principally on the linseed oil binder-based mock-ups among the acrylic and alkyd-based samples. Moreover, principal component analyses (PCA) and hierarchical cluster analyses (HCA) of THM-GC/MS results highlight that those changes were mostly dependent on the exposure time and on the type of pigment, while being independent of the lighting system used. Finally, semi-quantitative µ-ATR-FTIR results show slight pigment enrichment at the paint surface due to the auto and photo-oxidative degradation of the linseed oil binder.

scholarly journals Feasibility Study on Measuring the Particulate Matter Level in the Atmosphere by Means of Yagi–Uda-Like Antennas

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3225 ◽  
Author(s):  
Aarón A. Salas-Sánchez ◽  
Julian Rauch ◽  
M. Elena López-Martín ◽  
J. Antonio Rodríguez-González ◽  
Giorgio Franceschetti ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Simulated Annealing ◽  
Method Of Moments ◽  
Surrounding Medium ◽  
Measurement Procedure ◽  
Characteristic Parameters ◽  
Trade Off ◽  
Promising Solution ◽  
Moderate Length ◽  
Concentration Levels

In this work, the application of a technique for monitoring changes of the dielectric constant of the atmosphere caused by the presence of pollution is discussed. The method is based on changes in the reflection coefficient of the device induced by these dielectric constant variations of the surrounding medium. To that end, several Yagi–Uda-like antenna designs with different size limitations were simulated by using a Method-of-Moments software and optimized by means of a simulated annealing strategy. It has been found that the larger the optimal elements of the array are allowed to be, the higher the sensitivity reached. Thus, in a trade-off between sensitivity and moderate length (regarding flexibility purposes), the most promising solution has been built. This prototype has been experimentally tested in presence of an artificial aerosol made of PAO (polyalphaolefin) oil and black carbon inclusions of a size of 0.2 μm. As a result, potentials for developing a measurement procedure by means of changes in the characteristic parameters of the antenna led by different concentration levels of suspended particles in the surrounding medium are shown. In this manner, a local mapping of polluted levels could be developed in an easy, real-time, and flexible procedure.

scholarly journals An assessment study of absorption effect: LED vs tungsten halogen lamp for noninvasive glucose detection

2015 ◽  
Vol 08 (02) ◽  
pp. 1550013
Author(s):  
Nur Ain Mohd Aziz ◽  
Norhana Arsad ◽  
P. Susthitha Menon ◽  
Sahbudin Shaari ◽  
Zalhan Md Yusof ◽  
...  
Keyword(s):  
Light Source ◽  
Glucose Concentration ◽  
Light Emitting Diode ◽  
Linear Trend ◽  
Glucose Monitoring ◽  
Glucose Detection ◽  
Halogen Lamp ◽  
Noninvasive Methods ◽  
Noninvasive Technique ◽  
Halogen Lamps

Noninvasive glucose monitoring development is critical for diabetic patient continuous monitoring. However, almost all the available devices are invasive and painful. Noninvasive methods such as using spectroscopy have shown some good results. Unfortunately, the drawback was that the tungsten halogen lamps usage that is impractical if applied on human skin. This paper compared the light emitting diode (LED) to traditional tungsten halogen lamps as light source for glucose detection where the type of light source plays an important role in achieving a good spectrum quality. Glucose concentration measurement has been developed as part of noninvasive technique using optical spectroscopy. Small change and overlapping in tungsten halogen results need to replace it with a more convenient light source such as LED. Based on the result obtained, the performance of LED for absorbance spectrum gives a significantly different and is directly proportional to the glucose concentration. The result shows a linear trend and successfully detects lowest at 60 to 160 mg/dL glucose concentration.

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