Photoelectric Method Research Articles

Development of a Photoelectric Adjustment System With Extended Range for Fluorescence Immunochromatographic Assay Strip Readers

Fluorescence immunochromatographic assay (FICA) is a quantitative detection technique widely used in clinical diagnosis, environmental monitoring, and food safety. To deal with the limited applications caused by insufficient detection range, this paper proposes a photoelectric adjustment system suitable for FICA strip readers to expand its detection range. The photoelectric adjustment system is proposed based on the relationship between the excitation light intensity and the fluorescence intensity, which provides the optimal excitation light intensity and a stable baseline amplitude for the FICA strip reader. To verify the proposed system, it was applied to the strip reader we had previously developed. The results show that the linear detection range of the FICA strip reader was extended from 1.95-256 μg/mL to 1-1024 μg/mL after using the proposed method. At the same time, the accuracy of the FICA strip reader does not deteriorate and is in good comparisons with the conventional ESEQuant Lateral Flow Reader (with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> > 0.9987). Therefore, the proposed photoelectric adjustment method and system can improve the detection range of the strip reader or other similar devices.

Нові технології лазерної поверхневої обробки

Subject and purpose. Currently, gas, solid-state, and fiber lasers are used to process materials in the aviation industry. For the thermal treatment of steels, gas CO2 lasers with a capacity of more than 1 kW used, which are reliable in operation but have high cost and low efficiency. There are no results on the use of low-power (up to 20 W) pulsed-mode lasers for surface hardening of steel products. The purpose of this work is to determine the modes of surface hardening of products from carbon and alloy steels using low-power solid-state pulsed YAG lasers. Methodology. For laser hardening, a 5 W solid-state YAG laser was used (diode pumping, radiation wavelength λ = 1,064 μm, pulse mode). The use of a nonlinear crystal made it possible to obtain UV radiation with λ = 0,355 μm (third harmonic). The following modes were investigated: processing with single pulses (duration 0,1...0,4 ms) and multi-pulse processing with short (30...70 ms) pulses. The scanning speed was 8...2 mm/s. The energy in the pulse was determined by the photoelectric method. Thermal hardening was performed on the following steels: У12, P6M5. The possibility of UV radiation hardening was evaluated on steel 20, 45, У12, and ШХ15. Findings. The optimum values of pulse duration for maximum hardness in laser hardening of the investigated steels. With multi-pulse treatment of steels, the pulse duration is shorter than with single-pulse treatment, the hardening intensity is higher, and the quality of the processed surface is better. Single-pulse and multi-pulse processing are accompanied by partial melting of the surface of steel products, which does not allow it to be used in cases where a high quality of the surface is required. Laser hardening of steel by ultraviolet radiation is not accompanied by melting. Conclusion. For surface hardening of products, where partial melting of the surface is possible, low-power lasers in pulse mode can be used. Laser hardening by ultraviolet radiation is a promising direction for thermal hardening of steels, which allows maintaining the original quality of the surface layer. Thermal hardening with low-power lasers can be effective for small-sized areas of the processed parts of the fuel equipment of aircraft engines, friction elements, and, especially, the tool is small.

Machine Learning Method for Continuous Noninvasive Blood Pressure Detection Based on Random Forest

In order to reduce the influence of differences in human characteristics on the blood pressure prediction model and further improve the accuracy of blood pressure prediction, this paper establishes support vector machine regression model and random forest regression model for accurate blood pressure measurement. First, the photoelectric method is used to obtain the photoelectric plethysmography signal (PPG) and ECG signals from people of different ages, and the blood pressure value is roughly estimated based on the high-quality physiological signals and the vascular elastic cavity model; then the human body characteristics are used as the input parameters of the blood pressure prediction model, and the model parameters are used to find the best parameter combination to improve the prediction performance of the model; finally, through a lot of training and learning, the best blood pressure prediction model is selected to achieve accurate measurement of blood pressure values. It has been verified by experiments that the average absolute error of diastolic and systolic blood pressure based on the random forest optimization model meets the standard of less than 5mmHg formulated by AAMI (American Medical Instrument Promotion Association), which is better consistent with the method of mercury sphygmomanometer, and has more excellent performance than support vector machine regression model under the same conditions.

Photoelectric Detection System and Machine Learning Recognition Method of Its Detection Images

In the photoelectric detection system, the photoelectric detector can convert the optical signal to be measured into a current signal, and the current amplifier transforms the current signal output by the detector into a voltage signal for amplification. In this study, the photo-multiplier tube (PMT) is selected as the photoelectric detector. Compared with other photoelectric detectors, it can obtain higher internal gain, higher sensitivity, and better response performance. The current amplifier is prepared by pre-amplifier and voltage amplifier. In order to capture photoelectric signals well, a large-format scanning system is set up to design each component module, control module, and host computer module of the system. Besides, a machine learning-based algorithm is proposed, namely semi-supervised manifold image recognition algorithm, which is used for identify photoelectric detection images. In the test process, the printed circuit board (PCB) and sapphire material are firstly used as the substrate of the current amplifier, and their influences in the circuit are compared. The peak value of the output noise of each substrate circuit is around 2.8 mV when the input of the current amplifier is short-circuited. Then, the signal gain and signal bandwidth of the photoelectric detection system remain stable when there is no optical signal input. During the process of changing the system signal gain ratio, the noise output of the system is the lowest when the voltage of PMT is 0.50 V and the current amplifier gain is set to 2.2 × 105 V/A. The proposed recognition algorithm can identify different types of targets well. After the image is projected into a two-dimensional space by the algorithm, the distance between classes increases, and the targets in the class promote aggregation, thereby enhancing the identify-ability between samples.

Photoelectric pod drift calibration method based on navigation system

The accuracy of stability control is an important indicator of photoelectric pod system. In order to reduce the effect of gyro drift on stability accuracy in stabilized sighting control, the gyro drift needs to be compensated. A method of drift measurement and compensation was introduced for the photoelectric pod based on the navigation system, which was designed to calculate the component of earth rotation in the platform by the position and attitude data of airborne navigation system and pod angle during drift measurement phase of photoelectric pod, so as to obtain a more accurate gyro error. And in the stable phase, the gyro error and earth rotation component were compensated respectively by the navigation system. This method could effectively separate the earth rotation component and gyro error in the gyro drift measurement stage and adjust earth rotation component in the stable stage, so that the stability precision of stabilized sighting system could be improved. The experimental results show that, by comparing the results of 10-minute traditional drift measurement and drift measurement based on the navigation system, the accumulated drift error is stably controlled, the pitch angle is reduced from 1.80° in traditional method to 0.04°, and the heading angle is reduced from 0.77° to 0.04°.

二维半导体红外光电探测器研究进展（特邀）

Infrared detection plays an important role in cutting-edge fields such as biomedicine, smart cities, and space exploration. In recent years, a new type of nanoscale semiconductor represented by two-dimensional materials is one of the candidates for a new generation of infrared photodetection technology. This is due to the fact that some index of two-dimensional materials device have exceeded the theoretical limits of traditional thin-film devices, such as detection sensitivity, ultralow dark current, high working temperature, etc. Two dimensional materials can easily be controlled by local field. In this review, the mechanism of three local fields to achieve high performance at room temperature were introduced in the first part, including ferroelectric local field, the interlayer built-in electric field, and the in-plane built-in electric field. Secondly, we introduced the photoelectric enhancement methods of unilateral depletion heterojunction and surface plasmon structure to solve the problem of low quantum efficiency and low light absorption caused by atomic thin effect of two-dimensional materials. Finally, we showed some applications of two-dimensional materials in infrared photodetection field. The exploration reveals the potential and prospect of the novel two-dimensional semiconductor in the field of infrared photodetection, which provides some new methods and ideas for the new generation infrared detector technology.

Photoelectric test method for ground minimum control speed flight test

针对地面最小操纵速度试飞的光电测试需求，提出一种基于机载摄影测量与地面光电跟踪测量相结合的光电测试方法。简要介绍了地面最小操纵速度试飞光电测试系统设计；详细论述了系统标定、地面跟踪目标自动检测、基于机载摄影的飞机偏心距测量、基于光电跟踪测量的飞机航迹与速度测量等方法原理；总结了飞行试验测试实施流程；最后开展了飞行试验验证。试验结果表明，该方法有效可靠，可提供直观的飞机侧偏过程画面，实现飞机偏离跑道方向优于2 mm、高程方向优于2 cm和航向优于5 cm的定位测量精度，完全满足地面最小操纵速度试飞对光电测试数据的完整性、直观性和准确可靠性等要求。

Photoelectric Detection System for Large Board Parts

In-depth analysis of the current shortcomings in the detection of large board parts, a photoelectric detection method based on image processing technology is proposed, the overall structure of the detection system is designed in detail, the mechanical transmission system and the photoelectric detection system are specifically designed, and at the same time, the analysis the implementation steps of image processing for large-scale class parts using photoelectric detection technology are given. The specific implementation process is given, including: image acquisition, image stitching and image edge extraction, and finally the photoelectric online detection of large-scale board parts is completed.

Research on the influence of background light on the accuracy of a three-dimensional coordinate measurement system based on dual-PSD

PurposeThe purpose of this paper is to analyze the measurement error of a three-dimensional coordinate measurement system based on dual-position-sensitive detector (PSD) under different background light.Design/methodology/approachThe mind evolutionary algorithm (MEA)-back propagation (BP) neural network is used to predict the three-dimensional coordinates of the points, and the influence of the background light on the measurement accuracy of the three-dimensional coordinates based on PSD is obtained.FindingsThe influence of the background light on the measurement accuracy of the system is quantitatively calculated. The background light has a significant influence on the prediction accuracy of the three-dimensional coordinate measurement system. The optical method, electrical method and photoelectric compensation method are proposed to improve the measurement accuracy.Originality/valueBP neural network based on MEA is applied to the coordinate prediction of the three-dimensional coordinate measurement system based on dual-PSD, and the influence of background light on the measurement accuracy is quantitatively analyzed.

Research on the Portable and Intelligent Photovoltaic Power Generation System Based on Microgrid

A new design scheme of photovoltaic power generation system was proposed in the paper. The photovoltaic power generation technology was applied into an independent microgrid system, combined with intelligent grid technology and energy storage technology, and thus a portable and intelligent photovoltaic power generation system based on microgrid was constructed. The system was composed of solar power generation system, energy storage system, distribution apparatus and other parts. The photoelectric and line tracking methods were combined to make the battery panel conduct three-dimensional sun-chasing movement when it moves. The perturbation and observation method with variable step based on power prediction was raised so as to achieve maximum power point tracking. The battery energy management system was responsible for controlling the battery charging and discharging, as well as state detection, which ensured continuous and stable power supply of the load. The system could be expanded to build portable emergency power source, of great significance to rescue and relief work, military operation, field scientific investigation, navigation and so on.

Impact of Water Mist Extinguisher Construction on Parameters of Generated Drops

Abstract The paper analyses the impact that the construction of water mist extinguishers exerts on the size of generated drops. The test was based on the examination of three extinguishers of two producers, which have been available in the market in recent years. The test was carried out with the use of the IPS Drop Spectrum Analyzer (DSA). The device operates by using the photoelectric method to measure the parameters of the extinguishing stream microstructure. There were two measuring ranges: 0÷1 414 µm and 0÷2 658 µm. The test results present mean diameters of the generated drops, aggregated curves representative of their share as well as the analysis of the quality of spraying the extinguishing medium. The tests have shown that two out of three tested extinguishers do not generate water mist with standard parameters at a distance of 170 cm. The smallest mean diameters of drops were generated by extinguisher B, whereas the biggest ones by extinguisher C The highest level of spraying among all samples was found for extinguisher B. It’s Sauter diameter mean amounted to 564.03 µm. Further, it was shown what impact the construction of water mist extinguishers exerts on the size of generated drops.

Photoelectric detection of crop fungi resistance based on microfluidic

In view of the defects such as long time-consuming and large limitation in the detection of pesticide resistance of crop pathogens at present. A novel photoelectric detection method based on enriched microfluidic chips is proposed for the detection of pesticide resistance of crop fungal disease. First, according to the aerodynamics characteristics of microbial aerosol particles and optical detection technology, a special enrichment microfluidic chip was designed to achieve high efficiency enrichment and high precision concentration detection of fungal spores. On this basis, based on the theory of pesticide resistance sensitivity baseline, the relationship among spore germination, systematic enrichment concentration, and optical detection concentration of Botrytis cinerea in strawberry treated with Pyrimethanil was studied, and the pesticide resistance detection model of uncultured pathogens was established. The light intensity of light source was 1.1 × 103 cd, and the wavelength was 620 nm as the optimum parameters for optical detection. The correlation coefficient between the microscopic examination of spores’ concentration and the results of optical detection is 0.9792. It has good linearity and reliability, which provides a theoretical basis for the research and development of portable equipment for detecting pesticide resistance of crop diseases.

Influence of the Premises Dustiness Degree in an Educational Institution on the Choice of the Appropriate Air Filter Type

Students and teachers spend about 70% of the day in educational institutions. Therefore, recently in the world studies of the effect of air quality on human well-being and human performance have been conducted more often. The high content of suspended particles in the indoor air can lead to the development of allergies, and also serves as a factor of the transmission of respiratory viral infections. The purpose of this study was to determine the degree of dust in the indoor air in the classrooms. For this purpose, the photoelectric method of registration of aerosol particles and the Koch method were used. The results were evaluated according to two requirements for the amount of suspended particles in the air of the educational institution. Depending on the amount of suspended particles and their size, recommendations were given for filters to reduce the dust content of the internal air.

Analysis of the dynamic coordinate system using photoelectric lunar occultations

In this work we propose the determination of the astrophysical dynamic coordinate system’s orientation in relation to HCRF (Hipparcos Celestial Reference Frame) using photoelectric lunar occultation. The photoelectric method of recording an occultation that allows obtaining occultations moment with the accuracy up to 0.001s (i.e. 100 times more accurate than by visual method) was found to be the most accurate. Apart from the tasks of space geodesy, photoelectric observations allow carrying out other interesting researches, too. These tasks include determination of amendments to orbital longitude and latitude of the Moon and amendments to ephemeris time. The photoelectric observations of occultation are valuable materials for solving some astrophysical tasks. If one records changes in magnitude at the moment when a star is occultated by the Moon, then one may obtain diameter of the occultated star through the spectrum of those changes. Other important problems are detecting double and multiple systems of stars and measuring angular distances between their components.

Design of quadrant photoelectric detection system and method of displacement calculation

A quadrant photoelectric detection system was built to accurately measure the displacement of laser spot. The designation of the quadrant photoelectric detection system was separated into a theoretical part and an experimental part. In the process of deducing the theoretical formula, the addition-subtraction algorithm was utilized to derive the azimuth offsets of the Gaussian beam, and polynomial fitting functions were used to calculate the position of laser spot center. In the process of building experimental platform, a two-stage amplification circuit for the quadrant photoelectric detection system was specifically designed to enlarge the weak signals, and wavelet threshold denoising was utilized to reduce the noise of the output voltage signals. Moreover, an experimental platform was built as well to measure the position of laser spot center compared with theoretical ones. Both of simulations and experimental results show that the designed quadrant photoelectric detection system can preciously calculate the displacement of laser spot center, and the absolute position errors of measured spot center are less than 0.02 mm.

Method of Compensating for Trajectory Distortions of Relative Motion of the Writing Beam in Laser Image Generators with Circular Scanning

Proposals on compensation for distortions of circular trajectories implemented in laser image generators with circular scanning for increasing the accuracy of synthesis of the optical element topology are analyzed. The expected gain in the accuracy of the element topology formation is estimated with the use of a photoelectric method of detecting the beatings of the axis of rotation of the laser generator spindle rotor.

Using a Digital Camera Combined With Fitting Algorithm and T-S Fuzzy Neural Network to Determine the Turbidity in Water

We developed a method using a digital camera combined with fitting algorithm and T-S fuzzy neural network (T-S fnn) to measure the water turbidity accurately and efficiently. A turbidity-measuring device and image-processing software based on the common camera were designed to obtain the image of a standard solution after a constant light source passed through the sample and the RGB values, Lab values corresponding to the image were obtained. These RGB values were used as the input of the fuzzy neural network prediction model, the corresponding standard turbidity values were used as the output, and a camera-based fuzzy neural network turbidity measurement method was established. Simultaneously, the standard curve of turbidity measurement is established by fitting the turbidity using color component and color difference. The proposed method was applied to the measurement of standard turbidity solution and the results were compared with those of turbidmeter. The accuracy of the fuzzy neural network and the fitting algorithm is higher than that of the turbidimeter, and the accuracy of the fuzzy neural network method is the highest, the measurement error was only ±0.89%, and the accuracy much higher than that of an ordinary turbidimeter. By comparing the independent sample t-tests of the actual water samples, the fuzzy neural network method had the same trend as the turbidimeter and there was no significant difference of the results. The water turbidity measurement with the camera-T-S fuzzy neural network assembly can be applied to the actual water samples. This method can replace the traditional photoelectric detection method to measure turbidity, and it can reduce measurement error and cost. It may be used in environmental detection, biomedicine, and other fields.

Position Measurement of Laser Center by Using 2-D PSD and Fixed-Axis Rotating Device

Photoelectric non-contact measurement methods have been widely implemented in space target location, micro-displacement measurement and space optical communication. In term of the reliability and precision of measurement systems, it is a great significance to obtain the laser center location accurately. Since the two-dimensional position sensitive detector (2-D PSD) can continuously detects the gravity center position of the laser spot on its photosensitive surface, this paper provides a flexible method with high precision for the nonlinear correction of PSD as well as a new idea for PSD-based moving laser center positioning. Above all, a laser device system that rotating around a fixed-axis is designed, and the rotation angle can be controlled with the rotation accuracy of 0.5°. The trace of the gravity center of the rotating spot generated by the device on the PSD surface is detected, and then the laser center location is obtained after further processing of data. In order to improve the detection accuracy of PSD, this research mainly focuses on the nonlinear correction method of the detector and the fitting method of the gravity center trace of the laser spot. Moreover, the effects of different sizes of light spots projected onto the 2-D PSD on the collected photocurrent and estimated coordinates were analyzed by experiments. From the experimental results, the non-linear error of PSD is corrected by the error curved surface interpolation method, the overall error is reduced by more than 32%, and the linearity of the positioning of the laser moving along the diagonal of PSD is 0.2%.

Intracortical Neural Stimulation With Untethered, Ultrasmall Carbon Fiber Electrodes Mediated by the Photoelectric Effect.

Neural stimulation with tethered, electrically activated probes is damaging to neural tissue and lacks good spatial selectivity and stable chronic performance. The photoelectric effect, which converts incident light into electric potential and heat, provides an opportunity for a tetherless stimulation method. We propose a novel stimulation paradigm that relies on the photoelectric effect to stimulate neurons around a free-floating, ultrasmall (7-8μm diameter) carbon fiber probe. A two-photon microscope induced photo-stimulation with a near-infrared laser. Chronoamperometry and chronopotentiometry were used to characterize the electrochemical properties of photo-stimulation, while the fluorescence of Rhodamine-B was used to quantify temperature changes. Photo-stimulation caused a local cathodic potential pulse with minimal leakage current. Stimulation induced voltage deflections of 0.05-0.4V in vitro, varying linearly with the power of the laser source (5-40 mW). Temperature increases in the immediate vicinity of the electrode were limited to 2.5 °C, suggesting that this stimulation modality can be used without inducing heat damage. Successful stimulation was supported in vivo by increased calcium fluorescence in local neurons at stimulation onset in a transgenic GCaMP-3 mouse model. Furthermore, cells activated by photo-stimulation were closer to the electrode than in electrical stimulation under similar conditions, indicating increased spatial precision. Our results support the hypothesis that the proposed photoelectric method for neural stimulation is effective. Photoelectric stimulation is precise and avoids the need for a potentially destructive tether, making it a promising alternative to electrical stimulation.

Diagnostics of inhomogeneities of parameters of light-emitting heterostructures by the photoelectric method

The automated measuring complex for diagnostics of spatial inhomogeneity of parameters of light emitting heterostructures by photoelectric method with local photoexcitation is described. Results of the estimation of the homogeneity of the photocurrent value distribution on the area of crystals of blue and green commercial InGaN/GaN light-emitting diodes are presented. It is shown that near the crystal boundaries the level of inhomogeneity is higher than at the center. It is revealed that inhomogeneity of photovoltaic parameters of heterostructures of green LEDs is greater than that of blue LEDs.