Ratio Of Light Intensity Research Articles

Correction and quantification of MTF in scanning laser microscopy.

Observations using conventional microscopy often lack information related to the fine structures of an object, such as intensity and phase, because of limitations in the lens aperture. In this study, the intensity and phase information are appropriately converted into an electrical signal using laser scanning and photodetectors. Intensity and phase are completely separated, and the missing information is restored based on the frequency of the electrical signal. Using this method, the original intensity and phase information of the object to be observed can be correctly restored. Therefore, we propose a novel method to calculate the degree of intensity and phase modulation by calculating the direct and alternating current components obtained from the output of the sum and difference of the two photodetectors. The degree of spatial frequency modulation is corrected according to the electrical signal frequency to detect transparent or unstained cells. We first performed laser scanning of an object. Then, signals were detected using two photodetectors placed in the far-field, separated by the optical axis as the boundary. The output signals of the photodetectors were processed and the intensity and phase were unambiguously separated, thus allowing the visualization of the phase information of the transparent bodies and unstained cells. Spatial frequency correction was performed to correct the modulation. Our method successfully separated the information related to the intensity and optical path difference (OPD). In future work, by accurately correcting the intensity and OPD, it will be possible to separate the absorption rate from the ratio of the irradiation light intensity to the observed intensity and to separate the OPD into the refractive index and the thickness information. This method allows the accurate determination of these parameters in a noninvasive manner.

Temperature Effect on the Physical Properties of Enamel Paint Layer on Cement Plaster

The heating effect on the stability and visual colour of enamel paint on cement plaster is evaluated through light intensity ratio of three primary colours (RGB). The painted cement plaster is isochronally heated in an electric resistance furnace at different temperatures for one hour. The investigation of optical images reveals that the original colour of the paint layer on the plaster samples remains more or less unchanged up to heating at 100°C. However, thermal degradation of the samples becomes evident in colour when they are heated beyond 200°C and at 350°C the colour becomes already burned. The microstructural images of the samples at room temperature show fine and uniform grains. But at higher heating condition the microstructure of the colour sample is characterized by coarsening grain. The colour of the heated samples are then studied through tristimulus colour ‘L*’, ‘a*’ ‘b*’ and ‘E*’ values which were analyzed and evaluated in MATLAB software. The results show that after 200°C the hunter ‘L*’ value starts to decrease greatly up to 250°C. The hunter ‘a*’ value shows an increasing trend up to 100°C and then begins to decrease until 200°C. After 200°C the same increasing character is showed till 300°C. The change of hunter ‘b*’ value remains insignificant up to 100°C and shows decreasing trend between 100°C-250°C range and an increase after 250°C up to 300°C. It is graphically shown that the proportion of all three colours decreases with the increasing temparature. The overall change of colour ‘E*’ occurs with increasing heating temperature due to moisture releasing, chemical changes and thermal degradation simulteneously. The thickness of enamel paint layer comply the above degradation by showing the nature of decresing trend.
 Journal of Engineering Science 12(2), 2021, 103-108

An orthogonal design of light factors to optimize growth, photosynthetic capability and metabolite accumulation of Anoectochilus roxburghii (Wall.) Lindl.

Light is one of the key environmental factors influencing plant physiology and biochemistry, and light intensity (I),red and blue photon flux ratio (S) and photoperiod (P) are important light factors affecting plant growth, photosynthetic capability and metabolite accumulation. Nevertheless, little is known regarding the optimal combination of the three light factors for plant artificial cultivation and the effect of combination on plant physiology. In this study, Anoectochilus roxburghii(Wall.) Lindl., which is an important Chinese medicinal plant, was cultivated and continuously investigated under artificial light environment that the three light factors (I, S, P) were designed according to L16(43)orthogonal array. The results showed that all the light factors significantly affected leaf area, stem diameter, plant length, dry weight, flavonoids and polysaccharides contents. Red and blue photon flux ratio and photoperiod significantly influenced pigment content, but light intensity did not significantly influence it. Chlorophyll fluorescence analysis showed that high light intensity not only could lead light stress, but also could promote photosynthetic capacity by combination with red and blue photon flux ratio and photoperiod. The improved protocols I2S2P2(I=60 μmolm−2s−1, S=2:1 and P=10 h) and I4S1P4(I=100 μmol m−2s−1, S=1:1 and P=14 h) were validated and demonstrated to be the optimal combinations for growth and total polysaccharides content (I2S2P2) and for flavonoids contents (I4S1P4) respectively. This study also demonstrated that orthogonal array design is an efficient way to establish improved protocols of light for artificial cultivation of A. roxburghii.

Method for temperature measurement of taper long-period fiber Bragg grating

We report a temperature measurement method based on fixed wavelength transmission intensity of long-period fiber grating. Relative to wavelength or edge filtering, this method has obvious advantages in measurement accuracy and cost. The relationship between the transmission intensity and temperature at a fixed wavelength is simulated based on the theory of long-period fiber grating coupling mode. The results show that the transmission intensity of the fixed wavelength is linearly related to the temperature with the appropriate parameters. In the experiment, the transmission spectrum shows two resonant peaks at 1485 and 1538 nm. Two fixed wavelengths at 1480.4 and 1549.7 nm were selected, and the results show a linear relationship between transmission intensity and temperature. The temperature sensitivity of the transmission intensity at 1480.4 nm is about 0.0544 dB / ° C, which means the value of I1480.4 nm / I0 changes by 1.3% for every 1°C. To eliminate the influence of light source and enhance the measurement sensitivity, the ratio of the transmission intensity of two fixed wavelengths was selected to carry out the temperature measurement. The temperature sensitivity of the ratio of I1480.4 nm / I1549.7 nm was 0.0729 dB / ° C, that is, the light intensity ratio changed by 1.7% when the temperature changed by 1°C. A more reasonable design of long-period fiber grating and a more appropriate selection of fixed wavelength should be able to obtain higher temperature sensitivity.

Light Intensity Measurement of Kerr Effect Using Photodiode and High Speed Camera in Propylene Carbonate Under Applied DC Electric Fields

Light intensity is a resultant of Kerr effect measurement which later can be translated to electric field as well as charge density distributions in dielectric liquid. The light intensity can be measured either with photodiode or camera but measurement with both detectors has not been done yet. This study focuses on the comparison of light intensity measurement using Kerr effect with simultaneous detectors of photodiode and high speed camera. Hence, a pair of parallel electrodes is used in the experiment under high DC electric field. Propylene carbonate is used as the test liquid with Kerr constant, B of 1.41x10−12 mV−2. From the measurement results obtained, the light intensities from both detectors were compared and showed significant results as compared to the predicted light intensity ratio.

Wavelengths of LED light affect the growth and cannabidiol content in Cannabis sativa L

Given the special pharmacological value of cannabidiol (CBD), industrial hemp (hemp) has become a real “hot” crop. Though indoor farming of hemp has been widely used, the effects of red and blue light-emitting diode (LED) acting as supplementary light on the CBD synthesis in hemp remains unclear. Herein, a pot experiment with six treatments [CK, high-pressure sodium as light source, (R:B (ratio of red light to blue light) 9.30:1, PPFD (photosynthetic photon flux density) 191); LED1 (R:B 9.20:1; PPFD 129); LED2 (R:B 1.61:1; PPFD 540); LED3 (R:B 6.47:1; PPFD 28.2); LED4 (R:B 7.15:1; PPFD 41.7); LED5 (R:B 16.8:1; PPFD 252)] was carried out to study the effects of LED light quality on the growth and cannabinoid synthesis of hemp. Results showed that LED2 and LED5 could well maintain hemp growth compared with CK in terms of plant height, stem diameter, and leaf numbers. Compared with CK, the treatment of LED1, LED4, and LED3 significantly decreased the aboveground biomass, while LED2 and LED5 notably improved the aboveground biomass with an increment of 15.2 % and 55.1 %; the biomass of hemp flowers for LED2 and LED5 was markedly increased compared with that for CK with increments of 238 % and 61.5 %, respectively, but the other LED light treatments significantly reduced the flowers yield; LED2 could significantly increase the CBD content of both leaves (1.81 %) and flowers (5.83 %) compared to CK (leaves 1.38 %, flowers 4.27 %) while LED5 only notably increased the CBD content of leaves; among the LED treatments, the theoretic CBD yield for a per plant of LED2 and LED5 was 26.8 % and 9.0 % higher than that of CK. In conclusion, different red and blue LED light intensity ratios would dramatically influence the growth and cannabinoid synthesis of hemp, LED2 and LED5 can be good choices for indoor farming of hemp targeted for higher CBD yield.

An Intelligent IoT-enabled Lighting System for Energy-efficient Crop Production

In this paper, an intelligent lighting instrumentation and automation system is presented with the objective of achieving high energy-efficiency in greenhouse supplemental lighting based on the Internet of Things (IoT) technology. The system runs on a Raspbian operating system which interacts with wireless-enabled light emitting diode (LED) fixtures for plant growth, an online data server, and different light sensors including RGB and quantum sensors. The communication is achieved through RestFul API, UART, and I2C. The system is utilized to implement a feedback controller that automatically adjusts the light dimming levels and, in particular, the ratio of red and blue light intensities based on the plants’ needs. A series of experiments involving plant growth were conducted which indicate that the proposed system can achieve energy-savings up to 34%, when compared to a conventional time scheduling scheme. Additionally, the experiments demonstrate that the system can achieve a highly uniform light distribution under unpredictable natural lighting conditions while saving energy due to supplemental lighting.

Light-powered self-excited motion of a liquid crystal elastomer rotator

Self-excited motions have the advantages of directly harvesting energy from the environment, autonomy, and portability of the equipment, and consequently, the development of a wealth of new self-excited motion modes can greatly expand the application of active machines. In this paper, a rotator capable of self-excited movement is proposed, which consists of a liquid crystal elastomer (LCE) bar and a regular bar with an axle. Based on the dynamic LCE model, through theoretical modeling and numerical calculation, it is found that the LCE rotator has three motion modes, namely static mode, oscillation mode and rotation mode. The detailed dynamical process reveals the mechanism of self-excited oscillation and rotation. In this paper, the effects of parameters such as light intensity, damping coefficient, dimensionless gravitational acceleration, length ratio, illumination region and initial angular velocity on the self-excited oscillation and rotation are further studied systematically, and the corresponding limit cycles are given by various cases. The results show that the light intensity, damping coefficient and length ratio have important influence on the motion mode, while the initial angular velocity does not affect the motion mode. The influence of various parameters including light intensity and illumination region on the amplitude and frequency of self-excited oscillation is also studied. It is found that the amplitude mainly depends on light intensity and damping. This study can deepen people's understanding of non-equilibrium self-excited motions and provide promising applications in the fields of energy harvest, power generation, monitoring, soft robotics, medical devices and micro–nano-devices.

The Variation of Sapphire Substrate Shape of Micro LED Array to Increasing of Light Intensity and Contrast Ratio

The Variation of Sapphire Substrate Shape of Micro LED Array to Increasing of Light Intensity and Contrast Ratio

Real-time, non-invasive thrombus detection in an extracorporeal circuit using micro-optical thrombus sensors

Introduction:Real-time, non-invasive monitoring of thrombus formation in extracorporeal circuits has yet to be achieved. To address the challenges of conventional optical thrombus detection methods requiring large devices that limit detection capacity, we developed a micro-optical thrombus sensor.Methods:The proposed micro-optical thrombus sensor can detect the intensity of light scattered by blood at wavelengths of 660 and 855 nm. Two thrombus sensors were installed on in vitro circuit: one at the rotary blood pump and one at a flow channel. To evaluate the variation in the ratio of incident light intensity at each wavelength of the two sensors, Rfluct (for 660 nm) and Ifluct (for 855 nm) were defined. Using fresh porcine blood as a working fluid, we performed in vitro tests of haematocrit (Hct) and oxygen saturation (SaO2) variation and thrombus detection. Thrombus tests were terminated after Rfluct or Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test.Results:In all three thrombus detection tests, Ifluct showed a larger change than the maximum range of those in the Hct and SaO2 variation test. After the tests, thrombus formation was confirmed in the pump, and there was no thrombus in the flow channel. The results indicate that Ifluct is an effective parameter for identifying the presence of a thrombus.Conclusion:Thrombus detection in an extracorporeal circuit using the developed micro-optical sensors was successfully demonstrated in an in vitro test.

Light Quality Affected the Growth and Root Organic Carbon and Autotoxin Secretions of Hydroponic Lettuce.

Light is a crucial environmental signal and photosynthetic energy for plant growth, development, and primary and secondary metabolism. To explore the effects of light quality on the growth and root exudates of hydroponic lettuce (Lactuca sativa L.), white LED (W, control) and four the mixtures of red (R) and blue (B) LED with different R/B light intensity ratios (R/B = 2, 2R1B; R/B = 3, 3R1B; R/B = 4, 4R1B; and R/B = 8, 8R1B) were designed. The results showed that the biomass of lettuce under 8R1B and W treatments was higher than that under other light quality treatments. The photosynthetic rate (Pn) under red and blue light was significantly higher than that of white light. Total root length, root surface area, and root volume were the highest under 8R1B. 4R1B treatment significant increased root activity by 68.6% compared with W. In addition, total organic carbon (TOC) content, TOC content/shoot dry weight, TOC content/root dry weight, and TOC content/root surface area were the highest under 4R1B. Moreover, 8R1B treatment reduced the concentration of benzoic acid and salicylic acid, and the secretion ability of benzoic acid and salicylic acid by per unit root surface area and accumulation by per unit shoot dry weight. In addition, 2R1B and 3R1B reduced the secretion ability of gallic acid and tannic acid by per unit root surface area and accumulation by per unit shoot dry weight. In conclusion, this study showed that the secretion of autotoxins could be reduced through the mediation of red and blue light composition of LEDs in a plant factory. In terms of autotoxin secretion reduction efficiency and yield performance of lettuce, 8R1B light regime is recommended for practical use.

Optimization of CO2 biofixation rate by microalgae in a hybrid microfluidic differential carbonator using response surface methodology and desirability function

The atmospheric CO2 concentration has been increasing meaningfully in recent years and is involved in climate change. The conventional approaches to reduce atmospheric CO2 need significant area of storage related with high costs of monitoring, operation, and maintenance. The microalgae based CO2 capture is an environmentally sustainable choice and the captured CO2 is not required to dispose further. However, culture conditions of microalgae are very important to maximize CO2 biofixation rate. Therefore, this study is aimed to investigate the factors of CO2 biofixation rate utilizing Chlorella vulgaris microalgae in an in-house fabricated microreactor (a hybrid microfluidic-differential carbonator, μ-DC). Initially, the microalgal capability of biofixation was investigated at different independent variables: volume % of CO2, light intensity, and inlet ratio of microalgae to media. The effects of these variables were analyzed using full factorial design (FFD) and found that light intensity had less impact compared to others, while both CO2 concentration and mciroalgae to media ratio were found to be significant factors. The response surface methodology (RSM) with face centered central composite design (FC−CCD) and desirability function based approaches were then used for both single- and multi-objective optimization. In multi-objective optimization, the optimized conditions were: 6% CO2 in air and 0.018 microalgae to media ratio, at which specific growth rate (SGR) of 0.766 d−1, cell counts of 24.36 × 103 and CO2 biofixation rate of 0.2416 gL−1d−1 with high overall desirability value (D > 0.7). The values of the coefficient of determination (R2) for the fitted models were found to be more than 80 %. The predictive models were evaluated further based on other performance measuring indicators or error terms (e.g., relative error, mean absolute error, root mean square error) and these values were found apparently to be low, indicating that the model predictions were closer to the experimental results. ANOVA analyses showed that all developed models were statistically significant (p- values <0.05). The results are in good agreement with literature reports.

Biotoxoid Photonic Sensors with Temperature Insensitivity Using a Cascade of Ring Resonator and Mach-Zehnder Interferometer.

The great advances in silicon photonic-sensing technology have made it an attractive platform for wide sensing applications. However, most silicon photonic-sensing platforms suffer from high susceptibility to the temperature fluctuation of an operating environment. Additional complex and costly chemical signal-enhancement strategies are usually required to improve the signal-to-noise ratio (SNR). Here, a biotoxoid photonic sensor that is resistant to temperature fluctuation has been demonstrated. This novel sensor consists of a ring resonator coupled to a Mach-Zehnder interferometer (MZI) readout unit. Instead of using costly wavelength interrogation, our photonic sensor directly measures the light intensity ratio between the two output ports of MZI. The temperature dependence (TD)-controlling section of the MZI is used to eliminate the adverse effects of ambient temperature fluctuation. The simulation and experimental results show a linear relationship between the interrogation function and the concentration of an analyte under operation conditions. The thermal drift of the proposed sensor is just 0.18%, which is a reduction of 567-fold for chemical sensing and 28-fold for immuno-biosensing compared to the conventional single-ring resonator. The SNR increases from 6.85 to 19.88 dB within a 2 °C temperature variation. The high SNR optical sensor promises great potential for amplification-free detection of nucleic acids and other biomarkers.

Interaction of parametric instabilities from 3ω and 2ω lasers in large-scale inhomogeneous plasmas

The mechanism of energy transfer from 3ω pump light to stimulated Brillouin scattering (SBS) generated by 2ω pump light is proposed. The backscattering light of stimulated Raman scattering (SRS) generated by 3ω pump light can work as a seed of the SBS of 2ω pump light, which results in the increase of the latter. Adding 2ω pump light into 3ω pump light will decrease the reflectivity of SBS generated from 3ω pump light. The total reflectivity will first decrease and then increase with an increase of the ratio of 2ω light intensity to the intensity of 2ω and 3ω lights , and will be controlled in a lower level when this ratio f is about 10%−20%. These results give a method to control the total reflectivity of SBS and SRS in inertial confinement fusion (ICF) by adding 2ω light into 3ω light.

Estimating the leaf area index of bell peppers according to growth stage using ray-tracing simulation and a long short-term memory algorithm

The leaf area index (LAI), which represents crop growth characteristics, is used to calculate canopy photosynthetic rates, set irrigation standards, and predict crop growth. The LAI can be non-destructively and continuously estimated using the light-intensity ratio of the upper and lower crop canopy, but it is affected by solar altitude and external weather conditions. The objective of this study was to develop a method to estimate the LAI of bell peppers (Capsicum annuum L.) using the light-intensity ratio of the upper and lower crop canopy via solar altitude and weather conditions. Growth stages and weather conditions with solar altitude were set using 3D-scanned plant models and ray-tracing simulation, respectively. The light intensities at each location of the canopy for given conditions were calculated using ray-tracing simulation. The relationship between the light-intensity ratio and the LAI was analyzed using a long short-term memory (LSTM) algorithm, which is a type of artificial neural network. According to our results, the ratio varied depending on solar altitude and external weather conditions and exponentially decreased with increasing LAI. This LSTM algorithmic approach was able to quantitatively analyze this complex relationship; compared with a greenhouse experiment for validation, the algorithm was highly accurate (R2 = 0.808). Accuracy further increased when solar altitude and weather conditions were added to the model. Therefore, we conclude that, using this method, the LAI can be accurately measured in a non-destructive and continuous manner.

Angled fiber-based Fabry–Perot interferometer

Herein, we propose and experimentally demonstrate a novel, to the best of our knowledge, all-fiber Fabry–Perot (FP) interferometer that is formed by a simple angled fiber that can function as a beam splitter. According to the principle of the angled fiber, we verify the influence of an oblique angle on the light propagation path and light intensity ratio. Subsequently, angled fiber-based FP interferometers are experimentally demonstrated, and the influence of the oblique angle on the visibility of interference fringes and temperature characteristics is investigated. Finally, the temperature characteristics of this proposed FP interferometer are investigated experimentally, and the temperature sensitivity is 12.62 and 10.89 pm/°C for 42° and 40° angled fiber-based fiber FP interferometers, respectively. This proposed FP interferometer is fabricated by using a simple angled fiber, which has the advantages of ease of fabrication and all-fiber characteristics and hence can meet the requirements of mass production and high stability in various practical application areas.

Effect of Light Intensity and Quality on Growth Rate and Composition of Chlorella vulgaris.

In this research, the effect of solar irradiance on Chlorella vulgaris cultivated in open bioreactors under greenhouse conditions was investigated, as well as of ratio of light intensity in the 420–520 nm range to light in the 580–680 nm range (I420–520/I580–680) and of artificial irradiation provided by red and white LED lamps in a closed flat plate laboratory bioreactor on the growth rate and composition. The increase in solar irradiance led to faster growth rates (μexp) of C. vulgaris under both environmental conditions studied in the greenhouse (in June up to 0.33 d−1 and in September up to 0.29 d−1) and higher lipid content in microalgal biomass (in June up to 25.6% and in September up to 24.7%). In the experiments conducted in the closed bioreactor, as the ratio I420–520/I580–680 increased, the specific growth rate and the biomass, protein and lipid productivities increased as well. Additionally, the increase in light intensity with red and white LED lamps resulted in faster growth rates (the μexp increased up to 0.36 d−1) and higher lipid content (up to 22.2%), while the protein, fiber, ash and moisture content remained relatively constant. Overall, the trend in biomass, lipid, and protein productivities as a function of light intensity was similar in the two systems (greenhouse and bioreactor).

Dual-Wavelength (UV and Blue) Controlled Photopolymerization Confinement for 3D-Printing: Modeling and Analysis of Measurements.

The kinetics and modeling of dual-wavelength (UV and blue) controlled photopolymerization confinement (PC) are presented and measured data are analyzed by analytic formulas and numerical data. The UV-light initiated inhibition effect is strongly monomer-dependent due to different C=C bond rate constants and conversion efficacies. Without the UV-light, for a given blue-light intensity, higher initiator concentration (C10) and rate constant (k’) lead to higher conversion, as also predicted by analytic formulas, in which the total conversion rate (RT) is an increasing function of C1 and k’R, which is proportional to k’[gB1C1]0.5. However, the coupling factor B1 plays a different role that higher B1 leads to higher conversion only in the transient regime; whereas higher B1 leads to lower steady-state conversion. For a fixed initiator concentration C10, higher inhibitor concentration (C20) leads to lower conversion due to a stronger inhibition effect. However, same conversion reduction was found for the same H-factor defined by H0 = [b1C10 − b2C20]. Conversion of blue-only are much higher than that of UV-only and UV-blue combined, in which high C20 results a strong reduction of blue-only-conversion, such that the UV-light serves as the turn-off (trigger) mechanism for the purpose of spatial confirmation within the overlap area of UV and blue light. For example, UV-light controlled methacrylate conversion of a glycidyl dimethacrylate resin is formulated with a tertiary amine co-initiator, and butyl nitrite. The system is subject to a continuous exposure of a blue light, but an on-off exposure of a UV-light. Finally, we developed a theoretical new finding for the criterion of a good material/candidate governed by a double ratio of light-intensity and concentration, [I20C20]/[I10C10].

Research on Experimental Parameters of Reflective Off-axis Digital Holography

Summarized the research status of digital holography microscopy technology. Aiming at the experimental parameters which influences the quality of hologram recurrent image, the recording and reconstruction process of hologram are analyzed, the reconstruction distance are calculated which based on the reflective off-axis digital holographic light path. The experiment records the hologram of standard resolution board and reconstruct it under different light intensity ratio. The results show that the object and reference light intensity ratio have a significant impact on the quality of hologram recurrent image. Besides, it’s the key to determining an appropriate recording distance and object and reference light intensity ratio of improving the quality of hologram. The result would provide theoretical basis and technical conditions for studying the reflective digital holography based on 3-D reconstruction.

Time response of poly (ethylene naphthalate) light emission to charged particles

Poly (ethylene naphthalate) (PEN) has attracted attention as an undoped scintillation material. It is essential to understand its fundamental properties for future applications. Here, we show unique time responses of PEN light emission generated by charged particles. Light emission decays from a 5 mm thick PEN sample exposed to 241Am and 90Sr radioactive sources were both represented by two exponential functions for prompt and delayed components. The prompt and delayed decay constants for the alpha particles were τP = 28.7 ± 0.6 ns, τD = 161.4 ± 6.7 ns, respectively. In comparison, the prompt and delayed decay constants for the beta particles were τP = 28.9 ± 0.2 ns, τD = 257.0 ± 26.3 ns, respectively. We thus revealed an attractive feature that the delayed decay constants were significantly different for the two charged particles. In addition, the delayed/prompt light intensity ratios were 0.51 ± 0.04 for the alpha particles and 0.11 ± 0.02 for the beta particles. These differences caused the light pulses to be dependent on the type of charged particles. This knowledge enhances the advantages of PEN for radiation detection.