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In this study, we developed a new method for designing progressive addition-multifocus defocused freeform lenses. We used two independent meridians and achieved a smooth gradient transition of additional optical power from the center to the peripheral area of the lens, along with an asymmetric distribution of additional optical power on the nasal-temporal side of the lens. To improve the optical performance of the lenses, we developed three different designs based on the distribution of the additional optical power on the meridians. We conducted simulations and processing on the three different designs. The lenses designed using improved logistic regression and sine functions for meridian optical power distribution exhibited stable optical performance in the central focus area. They also met the design requirements for additional optical power. However, significant distortion was still observed in the peripheral region, which required further optimization. Lenses designed using piecewise linear functions for meridian optical power distribution exhibited relatively poor optical performance with significant optimization potential. Thus, combining the optical power distribution and surface-type factors for optimization is necessary. The proposed method enabled designing of defocus-free curved mirror lenses that satisfy the optical performance requirements. Thus, this method provides a new approach for the design of progressive addition lenses. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusions To investigate the potential improvement in visual acuity and subjective perception of image quality in patients with keratoconus using non‐orthogonal correction (NOC) cylinder trial lenses where the steep and flat power meridians are set at angles less or greater than 90°.A set of NOC plano/cylindrical trial lenses, where the axes between the power meridians were set at a range of non‐orthogonal angles, were used to refract 18 participants with keratoconus in whom 23 eyes were used for testing. Corneal elevation data were processed by bespoke MATLAB code from Pentacam Scheimpflug tomographer scans. Each participant first underwent subjective refraction using standard orthogonal cylinder trial lenses, and the monocular best‐corrected visual acuity (BCVA, logMAR) was recorded for each eye. They then underwent a second subjective refraction using NOC cylinder trial lenses created for the study and completed a questionnaire to elicit their subjective appraisal of letter clarity and ghosting.Fourteen (61%) eyes demonstrated an increase in objective BCVA with the NOC versus the orthogonal correction; seven (30%) eyes showed no change and in two (9%) eyes, the BCVA was slightly worse. Further, 87% and 79% experienced an increase in letter clarity and a reduction in ghosting, respectively, independent of changes in BCVA. The majority of non‐orthogonal angles were in the range of 80°–85°, and it was possible to refine the cylinder and axis of the NOC further compared with the orthogonal correction. All but one of the participants said they would be interested in trying non‐orthogonal spectacles if the opportunity arose.Correcting irregular astigmatism in keratoconic individuals with non‐orthogonal spectacle correction may provide benefit in terms of increased visual acuity, improvements in letter clarity and a reduction of ghosting effects. This type of correction has the potential to improve the overall quality of life for patients with keratoconus. [ABSTRACT FROM AUTHOR]

Abstract The deep ultraviolet (DUV) micro-light emitting diode (μLED) has serious electron leakage and low hole injection efficiency. Meanwhile, with the decrease in the size of the LED chip, the plasma-assisted dry etching process will cause damage to the side wall of the mesa, which will form a carrier leakage channel and produce non-radiative recombination. All of these will reduce the photoelectric performance of μLED. To this end, this study introduces polarized bulk charges into the hole supply layer (p-HSL) and the electron supply layer (n-ESL) respectively (dual-polarized structure) of the DUV μLED at an emission wavelength of 279 nm to enhance the binding of carriers and increase the injection efficiency of carriers. This is because the polarization-induced bulk charge can shield the polarized sheet charge on the interface and reduce the polarization electric field. The reduced polarization electric field in p-HSL can increase the effective barrier height of the conduction band in the p-type region and reduce the effective barrier height of the valence band. The decrease in the polarized electric field of n-HSL can reduce the thermal velocity of electrons, thereby enhancing the electron injection efficiency, reducing the Shockley–Read–Hall (SRH) recombination, and increasing the effective barrier height of the valence band. The study results indicate that the electron concentration and hole concentration of a μLED with dual polarization were increased by 77.93% and 93.6%, respectively. The optical power and maximum external quantum efficiency of μLED reached 31.04 W/cm2 and 2.91% respectively, and the efficiency droop is only 2.06% at 120 A/cm2. These results provide a new approach to solving the problem of insufficient carrier injection and SRH recombination in high-performance DUV μLEDs.

The deep ultraviolet (DUV) micro-light emitting diode (μLED) has serious electron leakage and low hole injection efficiency. Meanwhile, with the decrease in the size of the LED chip, the plasma-assisted dry etching process will cause damage to the side wall of the mesa, which will form a carrier leakage channel and produce non-radiative recombination. All of these will reduce the photoelectric performance of μLED. To this end, this study introduces polarized bulk charges into the hole supply layer (p-HSL) and the electron supply layer (n-ESL) respectively (dual-polarized structure) of the DUV μLED at an emission wavelength of 279 nm to enhance the binding of carriers and increase the injection efficiency of carriers. This is because the polarization-induced bulk charge can shield the polarized sheet charge on the interface and reduce the polarization electric field. The reduced polarization electric field in p-HSL can increase the effective barrier height of the conduction band in the p-type region and reduce the effective barrier height of the valence band. The decrease in the polarized electric field of n-HSL can reduce the thermal velocity of electrons, thereby enhancing the electron injection efficiency, reducing the Shockley–Read–Hall (SRH) recombination, and increasing the effective barrier height of the valence band. The study results indicate that the electron concentration and hole concentration of a μLED with dual polarization were increased by 77.93% and 93.6%, respectively. The optical power and maximum external quantum efficiency of μLED reached 31.04 W/cm2 and 2.91% respectively, and the efficiency droop is only 2.06% at 120 A/cm2. These results provide a new approach to solving the problem of insufficient carrier injection and SRH recombination in high-performance DUV μLEDs. [ABSTRACT FROM AUTHOR]

The digital twin was created and a prototype of the power supply system with power transmission via optical fiber was manufactured. This technology belongs to the field of optical, wireless and fiber optic power transmission (OWPT). Verification of correctness of the digital twin operation was carried out. The task of achieving the maximum possible efficiency of the system at varying load was solved. Its value amounted to 14%. The operability of the search algorithm of the double differentiation system developed for this purpose is shown. The principle of its operation consists in the change of optical energy synchronously with the change of load resistance. This allows to reduce losses in the primary and secondary energy converters. In the area of optimal regulation, the algorithm provides the minimum power supply level necessary for the operation of secondary devices, at which the maximum possible efficiency of the whole power supply system is achieved. The presented work is a part of the program of creating an end-to-end intelligent system of the full production cycle of the product, starting from the design of structures of opto- and photovoltaic converters (PC), up to the manufacture of systems adapted to individual customer requirements. [ABSTRACT FROM AUTHOR]

In this study, we developed a new method for designing progressive addition-multifocus defocused freeform lenses. We used two independent meridians and achieved a smooth gradient transition of additional optical power from the center to the peripheral area of the lens, along with an asymmetric distribution of additional optical power on the nasal-temporal side of the lens. To improve the optical performance of the lenses, we developed three different designs based on the distribution of the additional optical power on the meridians. We conducted simulations and processing on the three different designs. The lenses designed using improved logistic regression and sine functions for meridian optical power distribution exhibited stable optical performance in the central focus area. They also met the design requirements for additional optical power. However, significant distortion was still observed in the peripheral region, which required further optimization. Lenses designed using piecewise linear functions for meridian optical power distribution exhibited relatively poor optical performance with significant optimization potential. Thus, combining the optical power distribution and surface-type factors for optimization is necessary. The proposed method enabled designing of defocus-free curved mirror lenses that satisfy the optical performance requirements. Thus, this method provides a new approach for the design of progressive addition lenses.

This paper presents a simple engineering method for evaluating the optical power emitted by light-emitting diodes (LEDs) using infrared thermography. The method is based on the simultaneous measurement of the electrical power and temperature of an LED and a heat source (resistor) that are enclosed in the same plastic packaging under the same cooling conditions. This ensures the calculation of the optical power emitted by the LED regardless of the value of the heat transfer coefficient. The obtained result was confirmed by comparing it with the standard direct measurement method using an integrated sphere. The values of the estimated optical power using the proposed method and the integrated sphere equipped with a spectrometer were consistent with each other. The tested LED exhibited a high optical energy efficiency, reaching approximately η ≈ 30%. In addition, an uncertainty analysis of the obtained results was performed. Compact modelling based on a thermal resistor network (Rth) and a 3D-FEM analysis were performed to confirm the experimental results. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is one of the fastest wireless communication systems compatible with 5G and beyond. Therefore, it was necessary to employ rapid modulation systems compatible with intensity modulation / direct detection (IM / DD), such as Flip-FBMC modulation technology. The distribution of illumination units across the entirety of the room poses the greatest difficulty for the VLC distribution system. Previous models suffered from dark spots or blind spots in the center of the room, which is the user's mobility area, as well as high power consumption, which is one of the most influential factors influencing the system. This is the first instance in which the illumination units are distributed in new locations by five lights installed in the ceiling in order to eradicate dark spots by using a laser diode (LD) instead of an LED due to its high-intensity illumination. The optimal semi-angle and field of view were calculated to be 43o and 45o, respectively, in order to obtain the best results in terms of the received optical power and the preferred performance of the SNR distribution in comparison to the previous models, as well as to improve the power consumption of the illumination units. using the optimal values of the semi-angle at 43° and FOV at 45°, the current findings indicate that Model 3 also attained the highest optical power received and the best SNR distribution performance compared to the previous models. In this way, a complete illuminate distribution is obtained for the room. [ABSTRACT FROM AUTHOR]

Optimization of the light source layout is an important issue for indoor visible light communication systems, as it affects the received optical power distribution and user perception. In this paper, we propose a local optimization strategy for the light source layout that balances optimization effectiveness with optimization efficiency. First, we divide the optimization region into multiple sub-regions with different sizes and optimization priorities, where the sizes and optimization priorities of the individual sub-regions are determined based on the effect minimization principle among the sub-regions. We then calculate the pre-bias factor based on the equivalent mapping, which can compensate for the effect of the light sources in the latter optimized sub-region on the source layout optimization in the current sub-region. Finally, we search for the coordinate of a single light source for each sub-region using the variance of the squared distance between the projection of the light source on the receiving plane and the received point as a fitness function. Simulation results show that the proposed optimization strategy performs well when the vertical distance between the ceiling and the receiving plane is not less than 2.85 m. [ABSTRACT FROM AUTHOR]

Recently, the rapid development of LED sources emitting high-power radiation in the UVC range has been observed, and there is a growing interest in using these LED sources in practical solutions. The innovative constructions of disinfection and sterilization devices depend on the effectiveness and reliability of UVC radiation sources. At the same time, the literature reports that deep experimental analysis of degradation of high-power LEDs is limited. The aim of this research is to contribute to existing knowledge through a comparative assessment of the changes in optical power, spectral power distribution, and forward voltage drop in time and temperature of exemplary high-power UVC LEDs. For this purpose, a controlled 1500 h degradation of six different high-power UVC LEDs was performed, based on which we determined their expected lifetimes L70, L80, and L90. According to our results, the L80 varies from 180 h to 1500 h. Stronger degradation of optical power was observed with lower current. No significant impact on the spectral parameters was observed. The results also indicate the low influence of temperature on the voltage (<0.12%/°C), optical power (<0.22%/°C), and spectral parameters (peak wavelength Δλ and full width at half maximum ΔFWHM < 0.025 nm/°C). [ABSTRACT FROM AUTHOR]

A set of semiconductor lasers with different stripe widths is fabricated based on the AlGaInAs/InP heterostructure with an ultra-narrow waveguide. The key characteristics of the lasers (light-current curves (L-I), current-voltage curves (I-V), and spectral and spatial characteristics) are measured, and their dependence on the stripe width is shown. The operating optical power increases from 1.4 W to 4.3 W; however, the lateral brightness decreases from 1.09 W/(mm*mrad) to 0.65 W/(mm*mrad) as the stripe width increases from 20 to 150 μm. [ABSTRACT FROM AUTHOR]

A new mathematical model, optical-power-dependent model R(P), is proposed by investigating the nonlinearity of modified uni-traveling carrier photodiodes (MUTC-PD). Benefiting from this model, the harmonic power and output 3rd order intercept point (OIP3) of a photodiode can be calculated. Considering a bias voltage shift of the photodiode caused by a large voltage swing effect, the R(P) mathematical model is expanded into a voltage-related one, which is the optical-power-and-voltage-dependent model, R(P,V). The calculate results of both mathematical models are completely in accord with simulation results. [ABSTRACT FROM AUTHOR]

The main results of the studies on designing high-power semiconductor laser diodes based on asymmetric semiconductor heterostructures InGaAs(P)/Al(In)GaAs(P)/GaAs with low internal optical loss, whose concept was proposed at the Ioffe Institute, are described in detail. The basic technological approaches to designing highly strained active laser media for the spectral range up to 1100 nm are considered. The results of studying the cw high-power multimode semiconductor lasers, emitting in the wavelength ranges of 780–850, 900–980, and 1000–1100 nm; high-power pulsed semiconductor lasers; and high-power lasers with a very wide emitting aperture are considered. The key factors, determining the saturation of the output optical power of high-power semiconductor lasers, are determined. [ABSTRACT FROM AUTHOR]

This paper presents a simple engineering method for evaluating the optical power emitted by light-emitting diodes (LEDs) using infrared thermography. The method is based on the simultaneous measurement of the electrical power and temperature of an LED and a heat source (resistor) that are enclosed in the same plastic packaging under the same cooling conditions. This ensures the calculation of the optical power emitted by the LED regardless of the value of the heat transfer coefficient. The obtained result was confirmed by comparing it with the standard direct measurement method using an integrated sphere. The values of the estimated optical power using the proposed method and the integrated sphere equipped with a spectrometer were consistent with each other. The tested LED exhibited a high optical energy efficiency, reaching approximately η ≈ 30%. In addition, an uncertainty analysis of the obtained results was performed. Compact modelling based on a thermal resistor network (Rth) and a 3D-FEM analysis were performed to confirm the experimental results.

Optimization of the light source layout is an important issue for indoor visible light communication systems, as it affects the received optical power distribution and user perception. In this paper, we propose a local optimization strategy for the light source layout that balances optimization effectiveness with optimization efficiency. First, we divide the optimization region into multiple sub-regions with different sizes and optimization priorities, where the sizes and optimization priorities of the individual sub-regions are determined based on the effect minimization principle among the sub-regions. We then calculate the pre-bias factor based on the equivalent mapping, which can compensate for the effect of the light sources in the latter optimized sub-region on the source layout optimization in the current sub-region. Finally, we search for the coordinate of a single light source for each sub-region using the variance of the squared distance between the projection of the light source on the receiving plane and the received point as a fitness function. Simulation results show that the proposed optimization strategy performs well when the vertical distance between the ceiling and the receiving plane is not less than 2.85 m.

Recently, the rapid development of LED sources emitting high-power radiation in the UVC range has been observed, and there is a growing interest in using these LED sources in practical solutions. The innovative constructions of disinfection and sterilization devices depend on the effectiveness and reliability of UVC radiation sources. At the same time, the literature reports that deep experimental analysis of degradation of high-power LEDs is limited. The aim of this research is to contribute to existing knowledge through a comparative assessment of the changes in optical power, spectral power distribution, and forward voltage drop in time and temperature of exemplary high-power UVC LEDs. For this purpose, a controlled 1500 h degradation of six different high-power UVC LEDs was performed, based on which we determined their expected lifetimes L70, L80, and L90. According to our results, the L80 varies from 180 h to 1500 h. Stronger degradation of optical power was observed with lower current. No significant impact on the spectral parameters was observed. The results also indicate the low influence of temperature on the voltage (λ and full width at half maximum ΔFWHM < 0.025 nm/°C).

A set of semiconductor lasers with different stripe widths is fabricated based on the AlGaInAs/InP heterostructure with an ultra-narrow waveguide. The key characteristics of the lasers (light-current curves (L-I), current-voltage curves (I-V), and spectral and spatial characteristics) are measured, and their dependence on the stripe width is shown. The operating optical power increases from 1.4 W to 4.3 W; however, the lateral brightness decreases from 1.09 W/(mm*mrad) to 0.65 W/(mm*mrad) as the stripe width increases from 20 to 150 μm.

Copyright of Hungarian Medical Journal / Orvosi Hetilap is the property of Akademiai Kiado and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High‐quality glass is facing a significantly growing demand. Especially display glass and automotive applications are boosting the market and the industrial pursuit for highest quality, requiring not only defect free sheets but also flawless optical properties. The technology to be introduced in this paper concerns the measurement of optical power inhomogeneities of glass, additional to reliably detecting cords, reams, zip lines and other common optical glass defects. Quality monitoring also comprehensively gives hints for the optimization of the entire float glass process via product and quality data. By relying on the ISRA technology, manufacturers can ensure the delivery of defect‐free float glass with certified optical quality regarding Diopter or Zebra values. The paper provides a closer look at ISRA's patented innovative optical distortion measurement, giving an overview about how users can benefit from the in‐line Moiré technology, which ensures highest product quality and enhances global competitiveness. [ABSTRACT FROM AUTHOR]

A new instrument is required to accommodate the need for increased portability and accuracy in laser power measurement above 100 W. Reflection and absorption of laser light provide a measurable force from photon momentum exchange that is directly proportional to laser power, which can be measured with an electrostatic balance traceable to the SI. We aim for a relative uncertainty of $10^{-3}$ with coverage factor $k=2$. For this purpose, we have designed a monolithic parallelogram 4-bar linkage incorporating elastic circular notch flexure hinges. The design is optimized to address the main factors driving force measurement uncertainty from the balance mechanism: corner loading errors, balance stiffness, the stress in the flexure hinges, sensitivity to vibration, and sensitivity to thermal gradients. Parasitic rotations in the free end of the 4-bar linkage during arcuate motion are constrained by machining tolerances. An analytical model shows this affects the force measurement less than 0.01%. Incorporating an inverted pendulum reduces the stiffness of the system without unduly increasing tilt sensitivity. Finite element modeling of the flexures is used to determine the hinge orientation that minimizes stress, which is therefore expected to minimize hysteresis. Thermal effects are mitigated using an external enclosure to minimize temperature gradients although a quantitative analysis of this effect is not carried out. These analyses show that the optimized mechanism is expected to contribute less than $1\times 10^{-3}$ relative uncertainty in the final laser power measurement. [ABSTRACT FROM AUTHOR]

Cross-phase modulation (XPM) is one of the major limiting effects in wavelength division multiplexed (WDM) optical transmission systems. This paper mathematically investigates the impact of XPM-induced crosstalk with second (2OD), third (3OD) and combination of sub-planck higher-order dispersion (HOD) parameters for WDM systems at different combinations of effective core areas, optical powers, modulating frequencies and dispersion values. It has been observed that XPM-induced crosstalk increases with increase in optical powers, modulating frequencies and dispersion values, but it reduces for higher effective core areas. The results for 2OD, 3OD and combination of dispersion parameters up to eighth order (8OD) have been reported. For instance, with a transmission length of 50 km for different values of optical power ranging from 0.1 mW to 2 mW, crosstalk due to XPM was observed to vary from (−75 to −44 dB), (−172 to −144 dB) and (−275 to −250 dB) in the presence of 2OD, 3OD and ∑ n = 4 8 n O D \mathop \sum \limits_{n = 4}^8 n{\rm{OD}} combination, respectively. On the basis of analysis, one can select the appropriate frequency as well as the value of dispersion or type of fibre to achieve minimum crosstalk. [ABSTRACT FROM AUTHOR]

Semiconductor lasers with a 10-μm-wide lateral mesa-stripe waveguide are developed, and their radiative characteristics are studied. It is shown that the continuous wave (cw) optical power of lasers with a 4.6-mm-long cavity reaches 2.6 W at a heat-sink temperature of 25°C. Lasers with shorter cavities (<3 mm) showed lower maximum optical powers due to thermal rollover of the light–current characteristic. [ABSTRACT FROM AUTHOR]

Wireless epidermal wearable devices attract interests and expectations as a tool for personalized, low-cost health monitoring technology. The concept of the wireless attachable personal health monitoring devices has been more widely considered by combining them with biosensors. To bring the most advantage out of the structure of the epidermal attachable device, a battery-free approach was introduced to reduce the volume and extend the lifetime of the device. In this work, an energy harvesting technology and noninvasive sensor were applied with the attachable battery-free devices as a wireless power system and painless measuring system. A glucose sensor was used as an example to develop the wireless wearable device for diabetes-monitoring. The device consists of two functional parts: an optical power transfer and an electrochemical sensing part. The operation starts when the optical power transfer part accumulates power from series-connected photovoltaic cells and intermittently supplies the power to the electrochemical sensing part. In the electrochemical sensing part, an amperometric method was used for controlling the oxidation voltage and measuring a faraday current from the noninvasive sensor and current as brightness and duration of light pulses from a light-emitting diode (LED). The experiment results show that the device works as expected for a variety of glucose concentrations. [ABSTRACT FROM AUTHOR]

The paper reports on a method for calculating required elements parameters and output optical power level in fiber-optic interferometric schemes with time-division multiplexing (TDM) of sensing elements. In particular, the schemes based on fiber Bragg gratings are analyzed. The proposed method enables to ensure uniformity of powers of optical signals of individual sensing elements, as well as to evaluate how the deviations of elements parameters from the nominal ones influence the optical powers. The underlying mathematical foundations and the sequence in which the equations are applied are analytically proven. The principle of the proposed calculation method is illustrated through evaluation of several examples and the observed relations are discussed. The proposed calculation method can be applied for design of interferometric optical fiber sensors with multiplexed sensing elements.

In recent years, due to the effective achievements of IPL therapies such as treatment of spots, freckles, birthmarks, sunburn damage, vascular lesions, skin photorejuvenation, and hair and tattoo removal, IPL technology is of great interest especially in dermatology and aesthetic research. In this study, the temperature and optical power effects of an IPL therapy device on an artificial tissue were searched. Artificial tissues made of agar material were prepared to represent skins of two different color tones. The temperature measurement was performed via a thermocouple placed at a certain distance in the artificial tissue phantom. Optical power measurements were also taken from two different distances within the phantom. As a result of this study, it can be said that the IPL therapy device is safe and harmless for human use.

In this paper proposes a concept for independent calculation of parameters of elements in fiber-optic interferometric schemes with time-division multiplexing (TDM). The calculation method allows ensuring the equality of the optical power from all multiplexed sensitive elements, as well as evaluating the effect of deviation of the optical scheme parameters from the calculated ones. Using the example of two optical schemes, the implementation of this calculation concept, the sequence of obtaining mathematical expressions, and examples of calculation results are shown. The described calculation method can be directly used in the design of interferometric system with multiplexing of fiber-optic sensing elements.

Spatial resolution of conventional optics, which is necessary for nondestructive trapping of microobjects, is limited by diffraction to a value equal to half of the radiation wavelength. Despite this limitation, use of optical methods is one of the main directions in biological and biomedical researches because only these methods have a minimal impact on living organisms. The rapid advance in this area is largely owing to the development of new optical technologies and the considerable advance in mesoscale photonics, which has allowed researchers to develop techniques for controlling structured beams for optical traps. In this work, we consider some recent trends in the field of optical manipulation based on mesoscale dielectric particles. [ABSTRACT FROM AUTHOR]

The authors analyse a method, which leads to an efficient and precise algorithm for synthesising coaxial, optical fibre couplers of arbitrary modal electric‐field distributions. Their purpose is to design a fibre optic index profile supporting two pre‐selected mode fields such that their interference transfers all the optical power spatially from the core region to a cladding part of the optical fibre completely. To deal with this problem, they apply inverse transmission‐line techniques. Using the desired electric field, they work inversely and synthesise the appropriate refractive index profile of the couplers with excellent crosstalk. They envisage one can apply this technique to design fibre optic coaxial components acting as filters in sensing and numerous other applications. [ABSTRACT FROM AUTHOR]

Summary: In this study, a laser headlight driving controller (LHDC) using the controller area network (CAN)‐bus communication system was developed and implemented for vehicle headlight applications. To observe temperature variations that influence the forward‐bias voltage and optical power of laser diodes, the laser diode was placed in an ambient temperature‐testing chamber to measure the electro‐optic characteristics and calculate the electro‐optic conversion efficiencies. The optical power and conversion efficiency values obtained at different temperatures (from negative to positive temperatures) when optical power adjustment was executed using analog and pulse‐width modulation technologies were compared. Moreover, a human‐machine operating interface was developed using the LabVIEW software. Therefore, the LHDC and laser optical power can be controlled using a computer through the CAN‐bus communication system to control the LHDC and monitor it. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the variation in the optical power achieved following soft contact lens eye fitting for spherical and cylindrical lenses with differing hydrogel material properties. Methods: Uniaxial tensile tests were performed on four hydrogel materials 77% water-content (w-c) hydrogel, 74% w-c blue silicone hydrogel, 74% w-c clear silicone hydrogel, and 64% w-c clear hydrogel (shortly referred to as H77p0, SiH74p5-blue, SiH74p5-clear, and H64p0-clear), under loading conditions that would be expected in vivo. Finite element models of the cornea and contact lens interaction were generated using spherical and cylindrical lenses with powers varying from -10 to +20 D; overall diameters of either 13.5, 14.0, or 14.5 mm; and with material properties matching those determined through experimental testing. Results: The moduli of elasticity for each of the tested hydrogel materials were 0.195±0.027 MPa, 0.277±0.019 MPa, 0.279±0.01 MPa, and 0.457±0.013 MPa for H77p0, SiH74p5-blue, SiH74p5-clear, and H64p0 respectively. The calculated values of effective power change (EPC) showed strong negative correlations with lens power. This was particularly apparent in the higher end of the lens power spectrum (over +5 D), where each of the materials demonstrated a highly linear reduction in EPC with increased lens power. Conclusions: Soft contact lenses composed of a stiffer hydrogel are far more resilient to changes in EPC across the lower end of the lens power spectrum (-10 to +5 D). Beyond this range, the material choice does not have a significant effect on the EPC. [ABSTRACT FROM AUTHOR]

Electric devices have evolved to become smaller, more multifunctional, and increasingly integrated. When the total volume of a device is reduced, insufficient heat dissipation may result in device failure. A microfluidic channel with a graphene solution may replace solid conductors for simultaneously supplying energy and dissipating heat in a light emitting diode (LED). In this study, an automated recycling system using a graphene solution was designed that reduces the necessity of manual operation. The optical power and temperature of an LED using this system was measured for an extended period and compared with the performance of a solid conductor. The temperature difference of the LED bottom using the solid and liquid conductors reached 25 °C. The optical power of the LED using the liquid conductor was higher than that of the solid conductor after 120 min of LED operation. When the flow rate was increased, the temperature difference of the LED bottom between initial and 480 min was lower, and the optical power of the LED was higher. This result was attributable to the higher temperature of the LED with the solid conductor. Moreover, the optical/electric power transfer rate of the liquid conductor was higher than that of the solid conductor after 120 min of LED operation, and the difference increased over time.