Light Source Device Research Articles

Development and comparison of two devices for treatment of onychomycosis by photodynamic therapy

Onychomycosis is the most common nail disorder. The treatment for this type of infection is one of the main difficult ones in clinical practice, due to the fact that the nails are nonvascularized structures, which compromise the penetration of drugs delivered systemically and favor slow nail growth. We present two devices based on light-emitting diode arrays as light sources for the treatment of onychomycosis by photodynamic therapy (PDT). PDT is an emerging technique that uses a photosensitizer (PS) activated by light in the presence of oxygen. The PS absorbs energy from light and transfers it to oxygen, producing reactive oxygen species such as hydroxyl radicals, superoxide, and singlet oxygen which inactivate fungi and bacteria. Our proposal is the use of a portable and secure light source device in patients with onychomycosis. Additional advantages are the low cost involved, the possibility of topical treatment rather than systemic and the simplicity of operation. These advantages are important to ensure the implementation of this technology for the treatment of an impacting health problem.

Performance of a routing and wavelength assignment scheme for an optical‐carrier‐reusable ring network

This study investigates a heuristic routing and wavelength assignment (RWA) scheme for an optical-carrier-reusable ring network. This network has two unique features. First, only one light source, called the multi-carrier light source, is required which eases the difficulty of controlling many light source devices. Second, optical carriers are reused in order to improve the efficiency of wavelength usage. Given the target of wavelength-resource-efficient channel establishment, performance of the heuristic RWA scheme is evaluated. To realise efficient wavelength usage, the authors formulate the RWA problem as an integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths for given requests. With the ILP approach, the calculation process is not tractable in practical time. The heuristic RWA scheme introduced in this study solves the RWA problem. This scheme consists of two algorithms. Channel routes are obtained by the routing algorithm, and the wavelength assignment algorithm is then performed to assign a wavelength to each route. Moreover, two candidates, considering the shortest path and considering the avoidance of wavelength conversion, for the routing algorithm are examined. Numerical results show that the first candidate is more suitable in terms of reducing the number of required wavelengths than the second candidate.

Plannar light source using a phosphor screen with single-walled carbon nanotubes as field emitters.

We developed and successfully fabricated a plannar light source device using a phosphor screen with single-walled carbon nanotubes (SWCNTs) as field emitters in a simple diode structure composed of the cathode containing the highly purified and crystalline SWCNTs dispersed into an organic In2O3-SnO2 precursor solution and a non-ionic surfactant. The cathode was activated by scratching process with sandpaper to obtain a large field emission current with low power consumption. The nicks by scratching were treated with Fourier analysis to determine the periodicity of the surface morphology and designed with controlling the count number of sandpapers. The anode, on the other hand, was made with phosphor deliberately optimized by coverage of ITO nanoparticles and assembled together with the cathode by the new stable assembling process resulting to stand-alone flat plane-emission panel. The device in a diode structure has a low driving voltage and good brightness homogeneity in that plane. Furthermore, field emission current fluctuation, which is an important factor in comparing luminance devices too, has a good stability in a simple diode panel. The flat plane-emission device employing the highly purified and crystalline SWCNTs has the potential to provide a new approach to lighting in our life style.

White Light Emission of Polystyrene (PS) Thin Films Deposited by Spray Pyrolysis

The optical, structural and luminescent characteristics of polystyrene PS films doped with luminescent organic pigments (LOP) and deposited by spray pyrolysis technique are reported. The films are deposited on glass, quartz and GaN at low temperatures, using chemical solutions of recycled PS (from stayfoam) and LOPs as precursors, and N.N-dimethylformamide, as solvent.The thickness of the films was around 2.5 μm films showed at deposition rates between 100 and 200 Å/s. Doped films have roughness between 100 and 2500 Å depending on the kind of pigment used and the surface morphology shows that the organic pigments incorporate into the polystyrene host forming globular particles of about 2 µm in diameter. The organic pigments used have luminescent emissions peaked at 445, 510 and 590 nm.Non-doped films are very transparent and smooth; on the other hand, doped films are opaque and rough. The LOPs luminescent emission wavelengths were preserved when they were incorporated in the PS films. Using an appropriate mix of OPs it was possible to obtain films that have white light emission. These multi doped films were deposited on violet and blue light emitting LED chips, achieving a complete white light source device. It was determined that the exposure to the violet light from the LED degrades the luminescent characteristics, however, the blue light has is not energetic enough to cause a degradation of the luminescent layer over similar period of time.Emissions intensity behavior of photoluminescence depends of doping concentration and deposition temperature. The luminescence intensity had a maximum when the films were deposited at 240 0C in every case, save for the use of different concentrations of LOPs (~0.025 to 4%) in solution.The surface morphology and the root mean square surface roughness for PS thin films were determined by Atomic Force Microscopy, By UV-Vis technique, %T was measured. In addition, infrared spectra, Scanning Electron Microscopy images and EDS chemical composition results are also shown.Acknowledgments:The authors would like to thank SECITI (before ICyTDF) project PICSO12-119, and CONACyT México because of financial support.[1] S. Carmona-Téllez et.al., White light emitting transparent double layer stack of Al2O3 :Eu3+, Tb3+, and Ce3+ films deposited by spray pyrolysis, ECS Journal of Solid State Science and Technology, 2 (6) (2013)[2] A. E. Esperanza-García et. al. Luminescent and Morphological characteristics of Al2O3:Tb films deposited by spray pyrolysis using acetylacetonates as precursors. Journal of the electrochemical society, 150 (2) H53-h56 (2003)

A routing and wavelength assignment scheme in multi-carrier-distributed optical mesh networks with wavelength reuse

This paper proposes a routing and wavelength assignment (RWA) scheme that minimizes the number of required wavelengths for wavelength-reusable multi-carrier-distributed (WRMD) mesh networks. These networks have two unique features. First, only one light source, called the multi-carrier light source (MCLS), is required, which eases the difficulty of controlling many light source devices. Second, optical carriers are reused to improve the efficiency of wavelength usage. Since there are differences between the WRMD network and the conventional network, an efficient RWA scheme for the WRMD network is needed for wavelength-resource-efficient lightpath establishment. To realize efficient wavelength usage, we first formulate the RWA problem as an integer linear programming (ILP) problem of obtaining the minimum number of required wavelengths to satisfy the given requests. For large-scale networks, the ILP approach is not practical solution times. A heuristic RWA scheme is introduced in this paper to solve the RWA problem. Simulation results show that the proposed heuristic scheme with two carrier regenerations for the WRMD network approaches the near-optimum number of wavelengths. In addition, the optimum placement of the MCLS node is shown to reduce the number of required wavelengths for lightpath establishment, and achieve the optimum number of wavelengths.

Intraoperative Fluorescence Vascular Imaging Using Indocyanine Green for Assessment of Transplanted Kidney Perfusion

Introduction and ObjectiveIndocyanine green (ICG) emits infrared light with exposure to laser light. When intravenously injected, it binds to plasma proteins and predominantly persists in the vasculature, which is very useful for definition of the vascular network. The HyperEye Medical System (HEMS; Mizuho Ikakogyo Co., LTD, Tokyo, Japan) is a new device able to identify both near-infrared and visible rays “in situ” without needing to dim the operation room lighting. We speculated that intraoperative ICG imaging would be applicable for kidney transplantation, by providing “in situ” determination of successful vascular anastomosis. Materials and MethodsFour patients underwent intraoperative ICG imaging following intravenous administration of 1 mL of a solution containing 0.25% ICG. After performing vascular anastomosis, the allograft was examined using the HEMS light source device. Fluorescent signals were transmitted to a digital video processor connected to a television monitor and evaluated in real time. ResultsIn all 4 patients, intraoperative ICG imaging provided excellent resolution of blood flow at each step in real time, namely, coming from the recipient's artery to the allograft renal artery, circulating throughout the whole grafted kidney, and draining through the allograft renal vein to the recipient's vein. HEMS provides ICG fluorescence image in color, allowing surgeons to clearly discriminate the positional relationship between the target tissue and the surrounding tissue. No complications associated with ICG injection were noted. ConclusionOur preliminary results indicate that HEMS is a feasible and safe ICG imaging system that helps prevent technical failure during vascular anastomosis, and also demonstrates blood supply to the grafted kidney.

Tight Bounds on Channel Capacity for Dimmable Visible Light Communications

In this paper, the upper and lower bounds for the channel capacity of dimmable visible light communications(VLC) systems are investigated. Because the information is modulated into the instantaneous optical intensity, the transmitted optical intensity is represented by a nonnegative input that is corrupted by an additive white Gaussian noise. Considering the illumination support in a VLC system, the transmitted optical intensity signal must satisfy the illumination constraint, i.e., the average transmitted optical intensity is constrained by a target illumination intensity, which is determined by the nominal optical intensity of the light source devices and dimming target. An upper bound on the channel capacity is derived based on the signal space geometry via a sphere packing argument. A lower bound on the channel capacity is derived by maximizing the mutual information between the channel input and output. Both the upper and lower bounds are presented in closed forms. Furthermore, a closed-form optimal intensity distribution of the transmitted optical signal is obtained. The numerical results show that the presented bounds are very tight at the application zone of dimmable VLC links.

Radiative parameters for multi-channel visible and near-infrared emission transitions of Sm3+ in heavy-metal-silicate glasses

Multi-channel visible and near-infrared (NIR) emission transitions originating from 4G5/2 emitting state of Sm3+ in cadmium-aluminum-silicate (CAS) glasses with maximum-phonon-energy of ∼980cm−1 have been investigated. Based on the measured absorption spectrum, the Judd–Ofelt parameters Ωt (t=2, 4, 6) are derived to be 2.87×10−20, 3.34×10−20 and 1.86×10−20cm2, respectively. From the evaluated Judd–Ofelt parameters, the radiative parameters such as spontaneous emission probabilities (Arad), branching ratios (β), and radiative lifetime (τrad) are obtained from the 4G5/2 excited level to different lower energy levels. The efficient visible and NIR transition emissions have been observed in the Sm3+ doped CAS glasses, and the maximum stimulated emission cross-sections (σe-max) corresponding to emission peaks are calculated and demonstrated to lay in the same order of magnitude. The quantum efficiency of 4G5/2 level of Sm3+ has been derived to be 60%. Investigations on multi-channel radiative transition emissions originated from 4G5/2 level of Sm3+ in CAS glasses expose its potential applications in tunable laser, medical light source and NIR optoelectronic devices.

Localization properties at band edge of local density of states in two-dimensional Thue–Morse photonic systems

The spatial distribution of the local density of states (LDOS) at band edges on large-sized two-dimensional Thue–Morse dielectric systems has been investigated by means of a parallel implementation of the multipole expansion method. From the study of the LDOS participation number, the optical modes have been classified as critical, namely as intermediate between uniformly extended and exponentially localized. The exponent of power-law decay of their envelopes has been determined. Furthermore, multifractal analysis by a standard box-counting method has been performed. Almost all of the investigated modes exhibit a strong multifractal character. These results can be exploited for the designing of novel light source devices based on aperiodic order.

Cross-Polarisation, Making it Practical

The author investigated the use of cross-polarisation for day-to-day practice after a request from a clinician to remove specular highlights from intra-oral photographs. The paper evaluates camera and light source devices for image capture using cross-polarisation. Following this it defines ways to calibrate the camera to the correct white balance. It then develops by carrying out a series of tests to define the point of influence in regard to signal-to-noise ratio. These tests showed that the anti-aliasing filters of some cameras are more prominent than others and therefore can have a significant affect. In conclusion, when the appropriate equipment is employed, cross-polarisation is a viable and practical technique that has application within the medical, scientific, and forensic fields.

Efficacy of a Near-Infrared Light Device in Pediatric Intravenous Cannulation

To determine whether the use of a near-infrared light venipuncture aid (VeinViewer; Luminetx Corporation, Memphis, Tenn) would improve the rate of successful first-attempt placement of intravenous (IV) catheters in a high-volume pediatric emergency department (ED). Patients younger than 20 years with standard clinical indications for IV access were randomized to have IV placement by ED nurses (in 3 groups stratified by 5-year blocks of nursing experience) using traditional methods (standard group) or with the aid of the near-infrared light source (device group). If a vein could not be cannulated after 3 attempts, patients crossed over from one study arm to the other, and study nurses attempted placement with the alternative technique. The primary end point was first-attempt success rate for IV catheter placement. After completion of patient enrollment, a questionnaire was completed by study nurses as a qualitative assessment of the device. A total of 123 patients (median age, 3 years) were included in the study: 62 in the standard group and 61 in the device group. There was no significant difference in first-attempt success rate between the standard (79.0%, 95% confidence interval [CI], 66.8%-88.3%) and device (72.1%, 95% CI, 59.2%-82.9%) groups. Of the 19 study nurses, 14 completed the questionnaire of whom 70% expressed neutral or unfavorable assessments of the device in nondehydrated patients without chronic underlying medical conditions and 90% found the device a helpful tool for patients in whom IV access was difficult. First-attempt success rate for IV placement was nonsignificantly higher without than with the assistance of a near-infrared light device in a high-volume pediatric ED. Nurses placing IVs did report several benefits to use of the device with specific patient groups, and future research should be conducted to demonstrate the role of the device in these patients.

Photometric calibration for quantitative spectral microscopy under transmitted illumination

Over the past decade, there have been significant developments in the mechanisms for examination of biological and material samples. These developments exploit techniques in light microscopy to elucidate specific parts of cells and tissues, as well as inorganic particles. In recent years, spectral microscopy has become more prevalent for characterization of samples. Simultaneously, sensor technology has progressed as well and modern charge-coupled devices (CCD) cameras are now capable of achieving high spatial resolution and high sensitivity measurements of signals in the optical microscope. One major impediment in obtaining absolute quantitative information of imaged samples is the lack of automated photometric calibration mechanisms for spectral microscopes. In this paper, we present a methodology for achieving photometric calibration of an automated spectral imaging system targeted towards examination of biological samples. By acquiring spatial and spectral data simultaneously, spectral imaging allows one to exploit physical connections between a particle's morphology and its characteristic response to the optical spectrum. In composite biological material, the interpretation of the spectra is a complicated problem. This is because any light source and charge-coupled device camera used for data acquisition does not have a uniform illumination spectra and quantum efficiency, respectively, across the emitted light spectra. To balance the spectral response across individual wavelengths, our method modulates the exposure duration for the charge-coupled device camera during image acquisition. We present an image similarity based method to calibrate the system. Experiments to test the effectiveness of the calibration method under the various image similarity metrics are presented along with results to show the calibrated system's ability to accurately measure spectra based on the measured transmission profiles of optical filters.

GaN‐Si‐MEMS structure fabricated from nano‐column GaN quantum well crystal grown on Si substrate

AbstractNanocolumn‐crystallized InGaN/GaN quantum well crystals were deposited on Si (111) substrate. Photoluminescence measurement demonstrated a wide emission wavelength from about 400 nm to 700 nm. We propose a new light source device combined with Micro‐Electro‐Mechanical Systems (MEMS). The proposed device is monolithically composed of the GaN light source structures and Si MEMS. The direction of the light beam emitted from an array of the light source can be changed by a MEMS beam steering mechanism. A micro‐stage with comb actuators was fabricated from the Si substrate. The InGaN/GaN quantum well film is patterned on the micro‐stage. Basic researches on the growth of GaN crystals on Si substrate were also carried out. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Integration of optical waveguides with micro-incandescent light

In this work, we propose the integration of optical waveguides with a simple light source device. Light is emitted from an incandescent chromium micro-resistor embedded in a self-supported region of silicon oxynitride (SiOxNy) film. The waveguide structure is fabricated on a (100) silicon substrate using silicon oxynitride as the core and cladding layers. Bulk micromachining of the silicon substrate in KOH solution is used to free from the substrate the embedded micro-resistor, reducing the thermal dissipation of that region, allowing the resistor to heat up to incandescent temperatures. A comparison between a theoretical calculation and the experimental data indicate that the microlamp reaches 1160K before failure. After a microannealing process realized on the microlamp structure, it is possible to couple light into the waveguide and control the output power by adjusting the current that flows through the microlamp.

Reproduction of a computer-generated hologram with a white light source and liquid crystal device

The reproduction of computer-generated hologram (CGH) with white light source was realized using a liquid crystal panel instead of holographic film. The Burch-coding CGH was achieved by simulating the interference of a digital image and virtual reference light, displayed on liquid crystal displays and illuminated by a white light-emitting diode. The system is compact and the reconstructed images include full parallax. The full-parallax images of the Fresnel hologram computed with our algorithm were compared with the reproduced images by the rainbow hologram. The results implied this method was ready for the development of real-time three-dimensional color digital holography.

Video Presentations

The extended lymphadenectomy on esophagectomy for esophageal cancer contributed the improvement of late result but the operative invasion is very high, and the strict management was required postoperatively. Recently endoscopical surgeries are tried as the minimum invasive method in esophagectomy in Japan. Though, there are many problems in the accuracy of thoracoscopic lymphadenectomy and training period for stable technology. Then we have started a clinical trial of mini-thoraco-laparotomy (small incision) for the improvement of patient’s postoperative QOL without loosing any radicality since 1996. In mini-thoraco-laparotomy, thoracotomy was performed with small skin incision about 12–3 cm, and only the 5th intercostal muscle incision was necessary with other muscles preserved. In mini-laparotomy, intra-abdominal approach was made with 12–3 cm small skin incision in upper abdomen. Esophagectomy and lymphadenectomy was performed using super-long forceps and scissors over the gross view with the special light source device. Concerning to operation time, bleeding volume and quantity of lymphadenectomy, these were no difference between in Mini-type and Conventional-type operation. This mini-thoraco-laparotomy could have a certain advantage for early extubation, decrease of plumonal complication, shortening of SURS duration, and prevention of the wound infection. We believe our mini-thoraco-laparotomy could contribute for reduction of invasion of esophagectomy and improves the postoperative QOL with early recovery of postoperative pulmonal function. We will show these techniques of our mini-thoraco-laparotomy by video of middle thoracic advanced cancer case.

Optical Simulation of Light Source Devices Composed of Blue LEDs and YAG Phosphor

The optical structures and luminous properties of light source devices composed of blue LEDs and YAG phosphor were examined using optical simulation. Results showed that the reflection-type light source device had a high luminous flux over 1.5 times greater than the transmission-type light source device. This suggests that using light reflected from the phosphor is an effective way of obtaining high output from light sources composed of LEDs and phosphor.

カーボンナノチューブを電子源としたランプ型光源

カーボンナノチューブを電子源としたランプ型光源

Field emission of carbon nanotubes and its application as electron sources of ultra-high luminance light-source devices

Field ion microscopy (FIM) as well as field emission microscopy (FEM) of multiwall nanotubes (MWNTs) have been carried out to study the structure of their tips and the effect of adsorption of gas molecules on the electron emission. FIM images exhibited carbon pentagons at a nanotube tip in an atomic resolution, and also revealed changes in the tip structures under high electric field. In FEM experiments under various gas atmospheres (hydrogen, carbon monoxide, nitrogen and oxygen), adsorbates were recognized as bright spots in electron emission patterns, indicating enhanced emission of electrons through the adsorbates. Heating the MWNT emitter at about 1300 K allowed adsorbates to desorb. Hydrogen and nitrogen left the intact clean caps after their desorption, while carbon monoxide damaged partially the cap structure and oxygen destroyed significantly. Finally, our recent fabrication of nanotube-based ultra-high luminance light sources which provide intense light of 10 6 cd/m 2 for green at 30 kV DC-driving is reported.

青色LEDにYAG蛍光体を組み合わせた光源デバイスの光学シミュレーションによる検討

青色LEDにYAG蛍光体を組み合わせた光源デバイスの光学シミュレーションによる検討