Illumination Mode Research Articles

Psychophysics Study on LED Flicker Artefacts for Automotive Digital Mirror Replacement Systems

LED flicker artefacts, caused by unsynchronized irradiation from a pulse-width modulated LED light source captured by a digital camera sensor with discrete exposure times, place new requirements for both visual and machine vision systems. While latter need to capture relevant information from the light source only in a limited number of frames (e.g. a flickering traffic light), human vision is sensitive to illumination modulation in viewing applications, e.g. digital mirror replacement systems. In order to quantify flicker in viewing applications with KPIs related to human vision, we present a novel approach and results of a psychophysics study on the effect of LED flicker artefacts. Diverse real-world driving sequences have been captured with both mirror replacement cameras and a front viewing camera and potential flicker light sources have been masked manually. Synthetic flicker with adjustable parameters is then overlaid on these areas and the flickering sequences are presented to test persons in a driving environment. Feedback from the testers on flicker perception in different viewing areas, sizes and frequencies are collected and evaluated.

The Correlation Research on Reflection Characteristics of Road Tunnel’s Internal Surface & Lighting Quality

The internal wall and road surface of tunnel form the background of roadblock or vehicle together, and have a significant influence on the safety and comfort of tunnel lighting. In this paper, the optical simulation program is adopted to analyze the correlation between the reflectivity of tunnel wall and such illumination indexes as luminance and illuminance of road surface inside a tunnel, as well as the visibility of small target etc. It shows from the study that: (1) The reflectivity of wall on the luminance gain level of road surface is closely related to the luminous intensity distribution of lamps. (2) Under the circumstance that the luminous intensity distribution of lamps is consistent, the linear relations basically exist among the reflectivity of wall, the illuminance and luminance of road surface and the luminance of wall, while the maximum growth slopes are 11.29, 0.45 and 11.50 respectively. (3) The field of vision of driver can be significantly improved by a higher reflectivity of wall. (4) Compared with the three illumination modes, the visibility of small target under the pro-beam lighting is highest (the minimum visibility is 10, and the highest visibility can reach 11.6), while the visibility of small target under the counter-beam lighting is the second-highest and the visibility of small target under the symmetric lighting is most non-obvious.

Модули фотоэлектрических преобразователей лазерного (λ = 809-850 nm) излучения

A high-efficiency photovoltaic module optimized for converting the monochromatic radiation with a wavelength of 809-850 nm is presented. The module comprises four photovoltaic converters with the total area of 16 cm2, which can provide the operating voltage of 4 V in the case of laser power greater than 1 W. The laser power converters are developed on the basis of AlGaAs/GaAs structures grown by LPE and MOVPE. When operating in the uniform illumination mode, the efficiency of the photovoltaic module is found to exceed 60% for the powerful laser radiation (6.2 W).

Programmable pupil correction method for photolithography illumination system

The off-axis illumination (OAI) technology is one of the resolution enhancement technologies, and it used to reduce critical dimension (CD) and increase depth of focus (DOF) which are the important performance parameters of photolithography machine. The performance of illumination modes has great effect on critical dimension uniformity (CDU), H–V bias and overlay accuracy. In order that the pupil characteristic parameters can always meet the requirements for a long time using, it is necessary to adopt the pupil correction technology for photolithography illumination system. Using experiments and photolithography performance simulation, a programmable pupil correction method based on correction fingers is studied. The correction algorithm and its operation process are analyzed in detail. The experimental results show that the energy distribution of corrected pupils is more balanced than the uncorrected ones. Furthermore, the simulation results indicate that the corrected pupil could improve the exposure patterns in different aspects. The proposed method could determine the fingers’ position easily, and could directly reflect the pupil performance requirements.

Controllable vibration of liquid crystal elastomer beams under periodic illumination

The control of photo-induced vibration of liquid crystal elastomer(LCE) beams needs to be explored in depth considering the prospective applications in energy harvesters and active actuators. In this paper, the controllable bending vibration of liquid crystal elastomer cantilever beams driven by periodic light illumination is theoretically studied for the first time. Based on dynamic LCE model, semi-analytical solution to the light-driven bending vibration of the LCE beam is obtained by Mode Superposition Method. The numerical results show that periodic vibration of the LCE beam can be induced by periodic light illumination, and the vibration period of the beam depends on the period of the light illumination. For small damped systems, there exists an optimal periodic light illumination mode with the optimal period and optimal illumination time rate for the maximum steady-state amplitude of the forced periodic vibration. The optimal period is equal to the natural period of the beam, and the optimal illumination time rate is 0.5. With the increase of the illumination time rate, the vibration equilibrium position gradually moves towards the light source. For the optimal periodic illumination mode, the amplitude and reaction time of the bending vibration can also be controlled by light intensity, thermal relaxation time from cis to trans state, and damping factor of the beam, while the reaction time of the vibration in the beam mainly depends on the thermal relaxation time. The controllable vibration in this study is important for designing light-driven soft robots and photo-mechanical energy conversion systems.

Application of the structured laser illumination to planar optical diagnostics of the flows with nonuniform density

The aim of this work was to develop a method of panoramic optical diagnostics of the inhomogeneity of the density field in stratified flows based on the registration of the distribution of the Rayleigh scattering intensity using structured laser radiation. Several approaches have been implemented for organizing spatial modulation of laser illumination, intended for use with various values of the incident radiation energy density. To test the processing and reconstruction algorithms of the experimental data, a series of measurements was carried out using the method of planar laser-induced fluorescence. The distribution of local density in a jet of carbon dioxide flowing into atmospheric air was measured experimentally using a method based on the registration of Rayleigh scattering.

Image watermarking and fusion based on Fourier single-pixel imaging with weighed light source.

In previous single-pixel imaging systems, the light source was generally idle with respect to time. Here, we propose a novel image fusion and visible watermarking scheme based on Fourier single-pixel imaging (FSPI) with a multiplexed time-varying (TV) signal, which is generated by the watermark pattern hidden in the light source. We call this scheme TV-FSPI. With TV-FSPI, we can realize high-quality visible image watermarking, encrypted image watermarking and full-color visible image watermarking. We also discuss the extension to invisible watermarking based on TV-FSPI. Furthermore, we don't have to recode illumination patterns, because TV-FSPI can be extended to existing mainstream illumination patterns, such as random illumination mode and Hadamard illumination mode. Thus TV-FSPI has the potential to be used in single-pixel broadcasting system and multi-spectral single-pixel imaging system.

Smooth Surface Visual Imaging Method for Eliminating High Reflection Disturbance.

At present, visual imaging is widely applied for surface defects such as bumps and scratches in the manufacture of precise parts with a highly reflective surface. However, the high light reflection and halo disturbance as a result of the illumination in visual imaging exert a direct influence on the accuracy of defect detection. In this regard, the present paper develops an adaptive illumination method based on space–time modulation for a visual imaging system. Furthermore, a digital micro-mirror device (DMD) is employed to realize the pixel-level spatiotemporal modulation of illumination. Then, in combination with the illumination intensity feedback of charge coupled device (CCD), the time-space ratio is adjusted automatically to achieve adaptive uniform illumination and effectively suppress the high light reflection and halo disturbance of highly reflective surfaces. The experimental results show that, in terms of restraining high light disturbance, the visibility and accuracy of visual imaging are improved.

P6595The optogenetic defibrillation of ventricular arrhythmia in myocardial infarction rats in vivo

Abstract Introduction Optogenetics is a low-invasive, flexible and highly selective intervention that enables electrical excitation with light on myocardium overexpressing light-sensitive proteins. Optical illumination can control the simultaneous exciting of the whole myocardium under the spot, which is more conducive to recovery from electrical disturbance to sinus rhythm. Purpose We explored optogenetic defibrillation for different illumination parameters how to affect defibrillation rates and the possible mechanism of continuous illumination defibrillation. Methods Systemic delivery via right jugular vein injection of (AAV9-CAG-hChR2(H134R)-mCherry) were performed in juvenile SD rats to achieve the light sensitive protein Channelrhodopsin-2 (ChR2) transfer throughout the whole heart. We intubated and ventilated rats, opened chest and recorded the ECG. After ligation of the left anterior descending coronary artery, ventricular arrhythmia was induced by electrical burst stimulation (10v, 50Hz, 2s). Cardiac epicardium illumination with 470nm blue laser was performed to investigate the effects of optogenetic defibrillation and its underlying mechanism. Every heart accepted 30 pulses of 20ms duration on 8Hz to test the light intensity threshold for 1:1 capture. Different illumination modes of multiple light intensity (2,4,8,10,20 times threshold intensity), pulse duration (20, 50, 200, 500 and 1000ms) and illumination position (RV apex, RV, RVOT, septum, LV) were applied in each attempt for 4 repetitions with 1 s interval. Results We demonstrated that ventricular arrhythmias could be terminated by illumination of the right ventricle at 20 times threshold intensity in 1s (figure A) with the successful defibrillation rate of 95±2.673% (mean ±SEM; N=7). Herein, the successful optogenetic defibrillation rate was strongly depending on light intensity (N=5, n=50 episodes, p=0.0118) and duration of illumination (N=5, n=50 episodes, p<0.0001) (figure B.C). Notably when there were higher intensity and longer pulse duration, the higher defibrillation rate appeared. There was no significant difference in the defibrillation rate among different illumination positions (N=5, n=25episodes per position, p=0.1177) (figure D). To explore the underlying mechanism of optogenetic defibrillation, we performed the same illumination mode during sinus rhythm in 2 rats (figure E. F. G). We observed that higher light intensity and longer pulse duration were more conducive to induce an episode of higher frequency focal excitement. Views of optogenetic defibrillation Conclusions We demonstrated that optogenetic defibrillation is a highly effective intervention and the possible mechanism is partly attributed to overdrive suppression. We believe that optogenetic approach is potentially to be translated into more efficient and pain-free clinical termination of ventricular arrhythmia. Acknowledgement/Funding The national natural science foundation of China (81772044)

Optimization of Tubular Microalgal Photobioreactors with Spiral Ribs under Single-Sided and Double-Sided Illuminations

Microalgae can be raw materials for the production of clean energy and have great potential for development. The design of the microalgal photobioreactor (PBR) affects the mixing of the algal suspension and the utilization efficiency of the light energy, thereby affecting the high-efficiency cultivation of the microalgae. In this study, a spiral rib structure was introduced into a tubular microalgal PBR to improve the mixing performance and the light utilization efficiency. The number of spiral ribs, the inclination angle, and the velocity of the algal suspension were optimized for single-sided and double-sided parallel light illuminations with the same total incident light intensity. Next, the optimization results under the two illumination modes were compared. The results showed that the double-sided illumination did not increase the average light/dark (L/D) cycle frequency of the microalgae particles, but it reduced the efficiency of the L/D cycle enhancement. This outcome was analyzed from the point of view of the relative position between the L/D boundary and the vortex in the flow field. Finally, a method to increase the average L/D cycle frequency was proposed and validated. In this method, the relative position between the L/D boundary and the vortex was adjusted so that the L/D boundary passed through the central region of the vortex. This method can also be applied to the design of other types of PBRs to increase the average L/D cycle frequency.

Highly ordered combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles prepared by a novel route for dye-sensitized solar cells

Combined structure of anodic TiO2 nanotubes and TiO2 nanoparticles (TiNTs-TiNPs) has been synthesized by a facile combination of hydrothermal and chemical vapor deposition methods. Ordered TiO2 nanotubes with smooth walls were fabricated by two step anodization method in ethylene glycol containing NH4F at 50 V. This nanotubular array after annealing at 450 °C was subjected to the hydrothermally produced gaseous environment in an autoclave with diluted TiCl4 solution at its bottom. Vapors of TiCl4 were allowed to react chemically with water vapors for predefined time durations at 180 °C that resulted in the deposition of TiO2 nanoparticles on tubes’ surface and side walls. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that for one hour reaction duration, nanoparticles were evenly coated on the walls of nanotubes, whereas, longer durations tend to deteriorate the tubular structure. Consequently, the ordered TiNTs-TiNPs array produced after one hour coating has shown better performance for dye-sensitized solar cell DSSC) in back illumination mode with 130% increase in efficiency as compared to the device based on bare TiO2 nanotubes. The same photoanode has higher reflective properties with higher scattering ability. The solar cell based on this photoanode exhibits higher external quantum efficiency and effective charge transport properties. This study shows that porous ordered 1D structures based on TiO2 are of crucial importance for the high performance of DSSCs.

Research on energy‐saving power system of office building lighting based on Internet of Things

In order to solve the problem of lighting waste in developing countries and backward areas, an application of Internet of Things technology, combined with edge computing, is proposed to achieve intelligent lighting system for office buildings. The system takes the Internet of Things technology as the core, and combine ZigBee short-distance, low complexity, low-rate, low-power, low-cost and two-way wireless communication advantage, and based on mesh topology designs an energy-saving system for office building lighting. Intelligently control the switch of the luminaire or switch the preset illumination mode according to the sensed number of people in the current office, location and illumination brightness, effectively overcomes the defects of traditional lighting mode management backwardness, waste of energy, poor comfort and complicated wiring. The objective is to achieve the goal of energy saving and consumption reduction for office building lighting. Through practice and experimental test analysis, the improved energy consumption of the energy saving is about 30% per year, and the effect is remarkable.

Compromise between illumination performance and modulation bandwidth for micro-size white light-emitting diode by selecting injected current

The GaN-based white light-emitting diode (LED), in which 4 $$\times$$ 4 arrayed micro-pixels are packaged using chip-on-board technique, is fabricated for both illumination and visible light communication. The features of the electrical, optical, and communication characteristics related to the injected current are analysed. It is implied that the saturated injected current could be the optimised injected current for both illumination and communication, if the highest light-output power (LOP) and the largest 3-dB modulation bandwidth are desired. However, in order to improve the electro-optic conversion efficiency (EOC) and the lifetime for practical devices, the huge current density should be avoided and a small injected current should be better. In our experiments, if the injected current is reduced from the saturated injected current of 130 mA (4597.8 A/$$\hbox {cm}^2$$) to 20 mA (707.4 A/$$\hbox {cm}^2$$), the EOC and the lifetime of 95% LOP are improved from 3.1 to 11.4% and extended from 16.5 to 1560 h, respectively, while the total LOP of arrayed pixels and the 3-dB modulation bandwidth are still good values. The characteristics before and after the ageing process with different injected current are also discussed. It is shown that the ageing process has permanent degradation of the electrical and optical performance but has little effects on the modulation bandwidth of the 60-μm-diameter micro-LEDs in the experiments. Moreover, the small injected current leads to minimal degradation and would be the preferred choice.

Laser trapping of Ag nanoparticles to enhance Raman spectroscopy in aqueous media.

Laser trapping (LT) of metallic nanoparticles (NPs) is an approach that has the potential to enhance Raman spectroscopy in aqueous media. In this paper, we report the LT of multiple 60-nm Ag NPs using a tightly focused 1064-nm Gaussian laser beam. The dynamic process (trapping and escaping) of the individual Ag NPs were recorded using a charge coupled device (CCD) camera in backscattering illumination mode. We found that up to four Ag NPs could be simultaneously trapped; however, they were unstable in the laser trap due to Brownian motion and NP-NP interactions. However, after mixing Ag NPs with Bacillus subtilis, more of the Ag NPs could be trapped together with the bacteria. Furthermore, a 532-nm solid-state laser beam was used to activate Raman scattering of the Ag NPs + Bacillus subtilis sample. Based on repetitive measurements, the Raman spectra of the Ag NPs + Bacillus subtilis sample were enhanced and the results were consistent. Our work suggests that LT of metallic NPs can be used to enhance Raman spectroscopy in aqueous media. We believe that the enhanced Raman spectroscopy will be useful for real-time biological assays.

Flexible and precise control of cardiac rhythm with blue light

Optogenetics is an innovative method for precise control of biological function, which makes light manipulation displays more advantages than electric energy because of contactless spatial flexibility and cell-to-cell synchronous communication. The aim of this study was to perform different illumination modes with blue laser to investigate optical control of the mice hearts. In this study, we transfected the light sensitive protein ChR2(H134R) into mouse hearts, which were illuminated with a 473 nm laser on the Langendorff apparatus. We recorded all the signals of electrograms (EGs), epicardium monophasic action potential (MAPs) and light output signals to analyze myocardial electrical activity. EGs and MAP showed that ChR2 expression in the heart can be flexibly controlled by blue light across different illumination sites with corresponding triggered ectopic rhythm. Illumination intensity, pulse duration, and impulse frequency were associated with the light capture rate. Continuous illumination with the threshold intensity on the left ventricle had little influence on sinus rhythm and ventricular electrophysiology. Our results support that flexible control of the cardiac rhythm with optogenetics provides an innovative approach to cardiac research and therapy.

Pulsed Electrodeposition of Si Under Light Illumination in Ionic Liquid

Electrodeposition of Si has attracted much attention for its possibility to apply various areas such as photovoltaic cells and MEMS. Si thin film can be electrochemically fabricated with precise microstructural control and in a relatively simple process. However, it requires nonaqueous solvents due to very negative reduction potential of Si(IV). Ionic liquids are promising solvents for Si electrodeposition because of its unique characteristics such as nonflammable, non-volatile, and relatively wide electrochemical window. We have reported the electrochemical processing on Si thin films, nanodots, and nanopillars in trimethylhexyl ammonium bis-(trifluorosulfonyl) imide (TMHATFSI) ionic liquid containing SiCl4 as Si precursor [1-3]. Moreover, our recent paper [4] reports relatively smooth and compact Si thin films obtained by applying pulsed deposition, and smoother ones by applying light illumination additionally. Here we present the results of our work in the electrochemical processing of Si thin film with the pulsed potential modulation and light illumination. These experiments were conducted in order to promote the diffusion of precursor and light-assisted electrodeposition respectively. In the preliminary experiments, it turned out that the composition of Si film in pulse potential modulation [4] contained relatively large amount of impurities than the films potentiostatically deposited [3]. This result suggests that the oxidation currents during the rest period of pulse deposition may be partly responsible for such a larger impurity. Then, pulse potential modulation scheduling was further examined. Controlling the potential and current density considerably suppressed oxidation current. The composition of Si thin films was improved to recover to the level of potentiostatic electrodeposition. However, some cracks were still observed the surface. Thus, light illumination only in deposition time was superimposed. As a result, large cracks disappeared, and continuous and relatively smooth Si thin films with relatively low impurity were obtained. [1] T. Homma, J. Komadina, Y. Nakano, T. Ouchi, T. Akiyoshi, Y. Ishibashi, Y. Nishimura, T. Nishida, and Y. Fukunaka, ECS Trans., 41 (2012) 9. [2] Y. Ishibashi, T. Akiyoshi, J. Komadina, Y. Fukunaka, T. Homma, ECS Trans., 50 (2012) 117. [3] Y. Tsuyuki, A. Pham, J. Komadina, Y. Fukunaka, T. Homma, Electrochim. Acta, 183 (2015) 49. [4] Y. Tsuyuki, H. Takai, Y. Fukunaka, T. Homma, Jpn. J. Appl. Phys. 57 (2018) 08RB11.

ВЛИЯНИЕ БЛОКАДЫ КИССПЕПТИНОВЫХ РЕЦЕПТОРОВ НА ПОКАЗАТЕЛИ ПОВЕДЕНИЯ КРЫС В СТАНДАРТНЫХ ТЕСТАХ

Kisspeptin, the regulatory peptide, is known as a fertility stimulator and reproductive regulator. Its activity is mediated by specific interaction with GPR54 receptors (or Kiss1R). There are indications of correlation between the kisspeptin system in the brain and the function of circadian oscillator, the suprachiasmatic hypothalamus nucleus, which stimulates the cells of the kisspeptin neural network of the anteroventral periventricular nucleus in the hypothalamus, which in turn leads to the release of the hypothalamic gonadoliberin in the time period immediately preceding the start of the total daily locomotor activity. There is also evidence on the presence of fibers containing kisspeptin and on kisspeptin receptor expression in the suprachiasmatic nucleus, which indicates the function of kisspeptin as a feedback signal from the reproductive to the circadian system. Along with kisspeptin reproductive function, there is evidence on its importance in the behavior regulation. The aim of the work is to study the effect of intranasal administration of a specific GPR54 antagonist of p-234 receptors on the behavior of male rats in standard tests, such as “Open Field” and “Dark-Light box”. Materials and Methods. The experiments were conducted on 12 Wistar male rats weighing between 240 and 270 g. For control and experimental groups, the 12:12 h. light/dark illumination mode was set. The studies were conducted in the first half of the circadian day. In the experimental group the antagonist of p-234 kisspeptin receptors was administered intranasally; in the control group water for injection was administered using the same method. Results. Administration of kisspeptin receptor antagonist to experimental animals at the beginning of the subjective day led to a decreased anxiety level and stimulated the exploratory behavior in rats. Conclusion. The revealed behavioral changes can contribute to the implementation of the already known kisspeptin function as a reproductive stimulator, or act as an independent component in the physiological activity of a kisspeptin system. Keywords: antagonist of kisseptin receptors p-234, behavioral tests.

A novel strategy for the hyper-production of astaxanthin from the newly isolated microalga Haematococcus pluvialis JNU35

The two-stage cultivation system is widely employed for natural astaxanthin production using Haematococcus pluvialis, but the high biomass concentration of green vegetative cells (GVCs) is often difficult to achieve and little has been known about the combined photoinduction effect of light path (LP, inner diameter of 3 cm or 6 cm) and illumination mode (IM, unilateral or bilateral high light illumination). On the basis of isolating an excellent astaxanthin-producing algal strain (named H. pluvialis JNU35) and the optimized nutrient conditions, this study innovatively investigated the combined effect of LP and IM on biomass and astaxanthin hyper-production by this isolate. As a result, H. pluvialis JNU35 exhibited an ultrahigh biomass concentration of 20.1 ± 0.2 g/L and astaxanthin productivity of 18.1 mg/L/d under an optimum photoinduction combination (6 cm LP in the green stage, 3 cm LP in the red stage with bilateral high light illumination) in column photobioreactors. Moreover, an appropriate phase of GVCs being transferred into the red inductive stage was also determined to further increase the biomass concentration to 27.3 ± 0.6 g/L. By combining above optimal culture conditions, a novel culture strategy for enhancing astaxanthin production was proposed and validated in a flat-plate photobioreactor, which achieved a significant amount of astaxatnthin (5.6%, wt%) and a higher biomass concentration (3.0 g/L). This novel strategy will provide a technical solution for high-titer astaxanthin production from H. pluvialis for industrial scale.

An adaptive-coherence light source for hyperspectral, topographic, and flow-contrast imaging.

Colorectal cancer accounts for an estimated 8% of cancer deaths in the United States with a five-year survival rate of 55-75%. The early detection and removal of precancerous lesions is critical for reducing mortality, but subtle neoplastic growths, such as non-polypoid lesions, often go undetected during routine colonoscopy. Current approaches to flat or depressed lesion detection are ineffective due to the poor contrast of subtle features in white light endoscopy. Towards improving colorectal lesion contrast, we present an endoscopic light source with custom laser channels for multimodal color, topographic, and speckle contrast flow imaging. Three red-green-blue laser units, paired with laser speckle reducers, are coupled into endoscopic fiber optic light guides in a benchtop endoscope. Tissue phantom topography is reconstructed using alternating illumination of the laser units and a photometric stereo endoscopy algorithm. The contrast of flow regions is enhanced in an optical flow phantom using laser speckle contrast imaging. Further, the system retains the ability to offer white light and narrow band illumination modes with improved power efficiency, a reduced size, and longer lifetimes compared to conventional endoscopic arc lamp sources. This novel endoscopic light source design shows promise for increasing the detection of subtle lesions in routine colonoscopy screening.

An Accurate Illumination Model of Machined Surface Based on Micro-Image

This paper focused on the illumination model of machined surface based on micro-image. According to micro-image forming condition, the theory that the image brightness is related to the microfacet topography and surface reflection characteristics is presented. The distribution rule of micro-topography and reflection characteristics of sample surface is analyzed according to the measured data. An illumination mode of machined surface is established based on the analysis result, and the model parameters are obtained by using the simulated annealing algorithm. Verification results show that this proposed model can improve the simulation accuracy significantly and describe the lighting effect of machined surface. The research will provide a new idea and method for the 3D reconstruction.