Calibration Of Light Intensity Research Articles

Deep Semi-calibrated Near-field Photometric Stereo

Light calibration plays a crucial role in near-field photometric stereo for accurate surface normal estimation. It comprises light position calibration and light intensity calibration. In industrial applications, the light position calibration is typically performed once, as the facility remains fixed. However, the light intensity calibration needs to be repeated for real industrial scenes with variations in light intensity and fails for autoexposure industrial scenes. This study introduces a deep semi-calibrated near-field photometric stereo technique that achieves precise surface normal estimation without light intensity calibration. The technique consists of two parts: the near-field light intensity calibration network (NFLICN) and the near-field normal estimation network (NFNEN). NFLICN utilizes a point light model to self-calibrate pixel-wise light intensity. NFNEN, on the other hand, takes the calibrated light intensity as input and effectively utilizes local image features to estimate the surface normal. Experimental results on both synthetic testing datasets and the benchmark LUCES dataset confirm the state-of-the-art accuracy of our proposed method in surface normal estimation, even without light intensity calibration.

Optimizing Light Intensity with PID Control

Lighting is a fundamental cornerstone within interior design, possessing the capability to metamorphose spaces and evoke emotional responses profoundly. This principle applies to residential, industrial, and office domains, where lighting nuances are meticulously adjusted to enhance comfort and practicality. However, adequate luminance frequently intersects with energy wastage, often attributed to negligent light management practices. Mitigating this issue necessitates integrating light intensity controls adept at adapting to ambient luminosity and room-specific parameters. A prospective avenue encompasses incorporating a Proportional Integral Derivative (PID) control system synergized with light sensors. This research Implementing a closed-loop architecture, PID control utilizes feedback mechanisms to improve the precision of instrumentation systems. The PID methodology, consisting of Proportional, Integral, and Derivative control modalities, produces stable responses, accelerates system reactions, and diminishes deviations and overshooting by predetermined setpoints. The proposed Light Intensity Control System underpinned by PID methodology manifests as an exhibition of compelling outcomes drawn from empirical trials. The judicious selection of optimal parameters, specifically Kp = 0.2, Ki = 0.1, and Kd = 0.1, yielded noteworthy test outcomes: an ascent time of 0.0848, an overshoot of 6.5900, a culmination period of 0.4800, a settling period of 2.3032, and a steady-state error of 0.0300. Within this system, the PID controller assumes a pivotal role, orchestrating the regulation and meticulous calibration of light intensity to harmonize with designated criteria, thus fostering an environment of augmented energy efficiency and adaptability in illumination.Lighting is a fundamental cornerstone within interior design, possessing the capability to metamorphose spaces and evoke emotional responses profoundly. This principle applies to residential, industrial, and office domains, where lighting nuances are meticulously adjusted to enhance comfort and practicality. However, adequate luminance frequently intersects with energy wastage, often attributed to negligent light management practices. Mitigating this issue necessitates integrating light intensity controls adept at adapting to ambient luminosity and room-specific parameters. A prospective avenue encompasses incorporating a Proportional Integral Derivative (PID) control system synergized with light sensors. This research Implementing a closed-loop architecture, PID control utilizes feedback mechanisms to improve the precision of instrumentation systems. The PID methodology, consisting of Proportional, Integral, and Derivative control modalities, produces stable responses, accelerates system reactions, and diminishes deviations and overshooting by predetermined setpoints. The proposed Light Intensity Control System underpinned by PID methodology manifests as an exhibition of compelling outcomes drawn from empirical trials. The judicious selection of optimal parameters, specifically Kp = 0.2, Ki = 0.1, and Kd = 0.1, yielded noteworthy test outcomes: an ascent time of 0.0848, an overshoot of 6.5900, a culmination period of 0.4800, a settling period of 2.3032, and a steady-state error of 0.0300. Within this system, the PID controller assumes a pivotal role, orchestrating the regulation and meticulous calibration of light intensity to harmonize with designated criteria, thus fostering an environment of augmented energy efficiency and adaptability in illumination.

Importance of spectrally invariant broadband attenuation of light in indoor photovoltaic characterization

Indoor photovoltaic (IPV) devices are poised to make a significant contribution to the proliferation of the “Internet of Things” (IoT). For the accurate intercomparison of IPVs (and, hence, to advance the rational development of the technology), lighting conditions representative of those in typical indoor settings must be created reproducibly. As indoor lighting is invariably broadband, this will typically require the use of optical attenuation to achieve varying irradiance conditions at the device under test location. However, most forms of optical attenuation will suffer from some degree of spectral dispersion, creating sources of uncertainty for key figures of merit, such as power conversion efficiency. In this work, we examine the contribution of the mode of optical attenuation to the accurate characterization of IPV systems. We discuss requirements for broadband light source attenuation for the accurate characterization of photovoltaic devices under indoor illumination and consider the importance of using suitable reference devices for light intensity calibration. Furthermore, we experimentally verify attenuation methods typically used, including power control of the light source itself, use of neutral density filters, and advanced attenuation based on tandem prism attenuators. Finally, spectral shape alteration-induced uncertainties in performance parameter determination of photovoltaic cells under indoor illumination are quantified for three common broadband light attenuation methods, where we found ∼2%, ∼6%, and up to ∼15% ambiguity in photovoltaic device efficiency when using LED power control, prism attenuators, and neutral density filter-based broadband light attenuation, respectively.

A novel DOAS Retrieval algorithm without light intensity calibration

A novel DOAS Retrieval algorithm without light intensity calibration

Measurement of edge electron density profile with lithium beam emission spectroscopy (Li-BES) diagnostic on the experimental advanced superconducting tokamak (EAST)

Lithium Beam Emission Spectroscopy (Li-BES) diagnostic has been developed on the Experimental Advanced Superconducting Tokamak (EAST), aiming at providing the edge electron density profile and density fluctuation. This system has been upgraded to 32 × 4 (radial × poloidal) channels since the 2016 campaign with a radial observation range of about 30 cm at the midplane on the low field side. The spatial resolution of Li-BES diagnostic is about 1 cm. The whole optical system of Li-BES diagnostic has been shifted 9 cm away from the tokamak axis perpendicular to the flange at horizontal D-port on EAST since the 2017 campaign. It’s confirmed that transmissivities of Avalanche PhotoDiode (APD) channels in the edge region are improved by comparing the relative light intensity calibration factors of the same row of APD channels before and after the shift. Spatial calibration and relative light intensity calibration of this system have been performed. Based on Schweinzer’s algorithm [J. Schweinzer et al., Plasma Phys. Control. Fusion 34, 1173 (1992)], the edge electron density profile is reconstructed and shown to be consistent with those provided by other diagnostics on EAST. The electron density profile evolution during the plasma current ramp-down process is observed with Li-BES diagnostic in both SOL region and pedestal region. With an injected Li-beam under the high frequency chopping control, the temporal resolution of the reconstructed electron density profile can be up to 10 μs, which reveals temporal behaviors of fast transient events on EAST, such as the L-H transition and ELM crashes.

Analysis of CH* concentration and flame heat release rate in laminar coflow diffusion flames under microgravity and normal gravity

The chemiluminescence from electronically excited CH (denoted as CH*) is investigated in nitrogen-diluted laminar coflow methane diffusion flames under microgravity and normal gravity conditions. In combustion studies, this radical species is of significant interest since its spatial distribution is indicative of the flame front position; moreover, given the relatively simple diagnostic involved with its measurement, several studies have been done to evaluate the ability of CH* chemiluminescence to predict the total and local flame heat release rate. In this work, a subset of the publicly available NASA Structure and Liftoff in Combustion Experiments (SLICE) microgravity and normal gravity nitrogen-diluted methane flames has been considered, and a method to extract quantitative CH* concentration information from the SLICE raw data is demonstrated. The measured CH* concentration is then discussed and compared with numerical simulations to assess the correlation between CH* chemiluminescence and heat release rate. The spectral characterization of the digital single lens reflex (DSLR) color camera used to acquire the flame images allowed the signal collected by the blue channel to be considered representative of the CH* emission of the A2Δ → X2∏ transition centered around 431nm; the analysis of the spectral emission of a reference nitrogen-diluted laminar diffusion methane flame accounted for the contribution of chemiluminescence from emitting species other than CH*. Due to the axisymmetric flame structure, an Abel deconvolution of the line-of-sight chemiluminescence was used to obtain the two-dimensional intensity profile and, thanks to an absolute light intensity calibration, a quantification of the CH* concentration was possible. Comparisons with numerical results display reasonably good agreement between measured and computed flame shapes, and it is shown that the difference in peak CH* concentration, between micro- and normal gravity cases, is minimal. Independent of the gravity level, the integrated CH* concentration in a cross section scales proportionally to the integrated computed heat release rate. The two-dimensional CH* and heat release rate spatial profiles match in a satisfactory way, but the gradients and intensity distributions are not comparable.

Intensity-Modulated Spectroscopy on Loaded Organic Photovoltaic Cells

We configured a generic digital lock-in amplifier as a light intensity-modulated spectrometer for photovoltaic (PV) cells for intensity-modulated spectroscopy (IMS) up to 250 kHz. We performed IMS on a state-of-the-art bulk heterojunction (BHJ) organic PV (OPV) cell and introduced a new mode of IMS, wherein PV cells work under finite load, including maximum power point (MPP). Quantitative analysis supported by equivalent circuit simulations establishes MPP-IMS as favorable alternative to the commonly used intensity-modulated photovoltage/photocurrent spectroscopy (IMVS/IMPS) modes. Using IMS under finite load, we identify a high-frequency feature that is invisible in both IMPS and IMVS. The feature is ageing-related and becomes more prominent after long-term storage. We propose an extended equivalent circuit model that locates the origin of this feature at the BHJ itself and link it to diffusion of indium ions etched from the transparent electrode by the hole extracting PEDOT:PSS. Finally, we introduce a method to determine BHJ capacitance by IMS without absolute calibration of light intensity.

Soot and thin-filament pyrometry using a color digital camera

A simple and compact temperature and soot volume fraction diagnostic technique based on ratio pyrometry has been studied. Two different consumer digital single lens reflex cameras were evaluated for use as pyrometers. The incandescence from soot and a SiC filament was imaged at the three wavelengths of each camera’s color filter array (CFA). After characterization of the detector’s signal response curves, temperatures were calculated by two-color ratio pyrometry using a lookup table approach. A SiC filament with known emissivity was shown to provide an absolute light intensity calibration, which further allows the soot volume fraction to be determined. Measurements were carried out on four different flames with varying levels of soot loading. The filament-derived gas temperature and soot temperature measurements have been compared with computational results and overall good agreement has been shown. Soot volume fraction measurements have been compared with previous LII results, with excellent agreement for both cameras tested.

Measurement of acoustic wave frequency by Bragg light diffraction.

The new technology is offered for measurement of acoustic wave frequency. The method is based on using the Bragg light diffraction on the hypersonic transversal acoustic wave in a gyrotropic crystal. As is well known, the intensity of diffracted light in this case is strongly dependent from the quantity of specific rotation of polarization vector. As a result, using the standard calibration of light intensity it is possible to measure the changes of acoustic wave frequency. Measurements of the diffracted light intensity have been carried out in several points along the direction of the acoustic wave propagation. The applied sample of LiNbO3 was oriented along the crystallographic axis of the third order with the accuracy of 10′. The plane‐polarized transverse acoustic waves were excited in the frequency range from 900 MHz to 1.2 GHz. The results obtained at the average frequency 1.0 GHz were shown, that the intensity of diffracted light intensity is sensitive parameter to the change of the transverse acou...

Light Intensity, Photoperiod, and Diapause Induction in Face Flies (Diptera: Muscidae)

In the fall, adult face flies enter a facultative diapause in which mating and ovarian maturation do not take place, and their fat bodies become hypertrophied. Laboratory studies implicate short photoperiod as the primary inducer of diapause, but the response is temperature-dependent. Among field populations in Ames, Iowa, however, most teneral adults begin to enter diapause in the second week of September every year with no detectable effect of temperature. A range of light intensities <1,730 lux (160 ft-c) was applied to populations of flies at different photoperiods and temperatures. Precise calibration of light intensity was achieved with crossed polarizing filters placed over populations of eclosing flies. In a split-plot experiment, reduced light intensities led to significantly more diapause in each of four photoperiods. There was no interaction between photoperiod and light intensity. Effects of photoperiod and light intensity on diapause were obtained in split but not constant temperatures.