Illumination Method Research Articles

Wide-viewing full-color depthmap computer-generated holograms.

An efficient synthesis algorithm for wide-viewing full-color depthmap computer-generated holograms is proposed. We develop a precise computational algorithm integrating wave-optic geometry-mapping, color-matching, and noise-filtering to multiplex multiview elementary computer-generated holograms (CGHs) into a single high-definition CGH without three-dimensional perspective distortion or color dispersion. Computational parallelism is exploited to achieve significant computational efficiency improvement in the production throughput of full-color wide-viewing angle CGHs. The proposed algorithm is verified through the full-color binary hologram reconstruction experiments utilizing an off-axis R·G·B simultaneous illumination method, which suggests the feasibility of the full-color sub-wavelength binary spatial light modulator technology.

Daylighting of the Newest Christian Churches

Semantic and spatial changes in the options for using daylight compared to tradition are presented, based on the analysis of the architectural solutions applied in a number of modern Christian churches. According to popular belief, sunlight is used in most modern temples only as an architectural technique proving the skill of an architect, and as a means of interior decoration. The study showed that behind the abstract modern methods of illumination a temple, there is a deep connection with the earlier cultural tradition. Sunlight was one of the key means used for decorating interiors of Christian churches. The light pouring from windows of the dome drum or cutting through the twilight of the extended naves, highlighting an apse with the altar, or emphasizing the beauty of the sculpture, was the conductor of the Divine on earth. The quintessence of the presentation of “divine light” in architecture, which clearly shows the connection between God and man, are the Gothic monuments. From the end of the 19th – the beginning of the 20th century, temple architecture was rapidly changing. Renowned innovator architects of the 20th century offered their own vision of a modern temple. The extreme degree of individualization of the new objects of cult was based on a common principle: the rejection of the symbolic language traditional for Christianity. The architects were not tied to metaphors and images of biblical subjects. They boldly changed both the external appearance of a temple and the construction of its internal space, hence, its system of daylighting. Traditionally, sunlight was the semantic filling of the temple space. As a result of the present study, it has been shown that in the newest Christian churches, daylighting techniques, in their essence, replace the pictorial filling of the temple space with religious content. At the same time, the same techniques function as a modern interpretation for a number of traditional architectural methods used for lighting design of the temple space. By the examples of the works by Studio Zermani e Associati, Mark Cavagnero Associates, Vicens + Ramos, Königs architekten, modern interpretation versions for the themes of retablo, glowing cross, highlighting the altar space, and illumination of gilded surfaces are shown, and the upper and side illumination features of the newest temples are revealed.

Quantitative evaluation of latent fingermarks with novel enhancement and illumination

A variety of suspended silica and metal nanoparticles have been used over the last 20 years to enhance latent fingermarks. This study quantitatively evaluates enhancement of natural and sebum-enriched fingermarks from three adult subjects acquired with a consistent applied force on glass with a fingermark press using suspended commercially available polystyrene (PS) particles. Images of the enhanced fingermarks acquired with total internal reflection (TIR), or standard overhead white light (WL), illumination are compared with fingermarks enhanced with conventional methods including cyanoacrylate fuming. The different enhancement and illumination methods are quantified based on the brightness and contrast of the fingermark images, as well as the number of minutiae that can be identified and matched to those on an inked manually acquired “template” fingermark using automatic fingerprint identification system (AFIS) software. Enhanced fingermarks acquired with the press are shown to be more consistent than manually acquired fingermarks based on these metrics. The results demonstrate that TIR illumination from a large-area illuminator built in house gives enhanced fingermark images with more matched minutiae and contrast superior to that for WL illumination for all types of enhancement. “Wet-powdering” with PS particles gives fingermark images that are for the most part comparable in terms of the number of matched minutiae to fingermarks enhanced with more conventional methods, suggesting that this novel enhancement method has a performance comparable to conventional enhancement methods. Interestingly, the age of the fingermark appears to have almost no effect on this new type of enhancement; sebum-enriched fingermarks ranging in age from 12 h to 435 days appear to have statistically identical numbers of matched minutiae.

Real-time neural radiance caching for path tracing

We present a real-time neural radiance caching method for path-traced global illumination. Our system is designed to handle fully dynamic scenes, and makes no assumptions about the lighting, geometry, and materials. The data-driven nature of our approach sidesteps many difficulties of caching algorithms, such as locating, interpolating, and updating cache points. Since pretraining neural networks to handle novel, dynamic scenes is a formidable generalization challenge, we do away with pretraining and instead achieve generalization via adaptation , i.e. we opt for training the radiance cache while rendering. We employ self-training to provide low-noise training targets and simulate infinite-bounce transport by merely iterating few-bounce training updates. The updates and cache queries incur a mild overhead---about 2.6ms on full HD resolution---thanks to a streaming implementation of the neural network that fully exploits modern hardware. We demonstrate significant noise reduction at the cost of little induced bias, and report state-of-the-art, real-time performance on a number of challenging scenarios.

Holography-based structured light illumination for temporal focusing microscopy.

In this Letter, we present a holography-based structured light illumination (SLI) method to enhance the resolution of widefield temporal focusing microscopy (TFM). In the system, a digital micromirror device is employed to simultaneously disperse the incoming femtosecond laser to induce temporal focusing at the focal plane and generate designed structured patterns via a Lee hologram. As the generated structured patterns do not contain the zeroth order beam, it improves the contrast and modulation frequency. Mathematical models have been derived to calculate the electric fields at the focal plane and to explain the effects of improved optical cross-sectioning capability. Imaging experiments have been devised and performed on fluorescent beads and mouse kidney sections; the results demonstrate enhanced axial confinement and improved suppression of out-of-focus fluorescence. The new SLI method realizes high-resolution TFM and can be readily applied to other microscopy platforms for biophotonics applications.

A High-Resolution Microfluidic LAPS Imaging System for 3D Cell Metabolism Monitoring

A High-Resolution Microfluidic LAPS Imaging System for 3D Cell Metabolism Monitoring

APPLICATION OF DIFFRACTIVE OPTICAL ELEMENTS FOR OPTICAL-ELECTRONIC DIMENSIONAL INSPECTION SYSTEMS

The work is devoted to the application of diffractive optical elements in systems using the structured illumination method to the geometric parameters inspection of industrial articles. The objects of inspection in these systems are: weapon barrels, fuel pellets, fuel elements, spacer grids, ceramic ring insulators. The used diffractive optical elements are computer-synthesized holograms that focus laser radiation into geometric shapes, the configuration of which is optimally combined with the inspected objects shape.

An Evaluation of Annual Luminous Exposure from Daylight in a Museum Room with a Translucent Ceiling

The current study investigates the issue of computer-aided daylight evaluation in a museum room with a dropped translucent ceiling. In this type of room, daylight is admitted through classic windows located in the facade and then distributed in the plenum, which is located above the exhibition space and transmitted through the translucent ceiling into the museum room. This illumination method enables guiding daylight deep into the room, excluding the impact of direct solar radiation. The presented study is based on data obtained through computer-aided daylight simulation by DeLuminæ (DL-Light, ver. 11.0.9) software using the Radiance software for all calculations and real weather data for Wroclaw, Poland. A museum room of 12 × 12 m with three different heights of the plenums was simulated to establish an optimal relation of the width to height plenum ratio. Next, the annual exposure in K lx·h/year was calculated, as sensitive works of art may be subjected to damage caused by light exposure. To further reduce illumination, the simulation of an automatic shading system in the form of horizontal louvers was performed. The system was activated when certain illumination values were detected by the sensor on the building’s roof.

Quantum Leap beyond the Frontiers: ‘Currentism’ in Visual Arts Production in the Nsukka School

There exists no scholarly publication espousing on the driving force behind the restless aspirations of the Nsukka artists towards searching for and using commonplace materials that the potent environment provides for supports and media for studio art production. Following this, my intent is to discuss the Nsukka artists’ creative inclinations, bordering on styles, ideas, forms, materials and technique. Through hermeneutical analysis, I examine some useful insights in the formal and conceptual principles for which their recent and current artworks are foregrounded. Relying on historical, interpretative and analytical methods of data illumination, I engage some selected unusual artworks executed between 1999 and 2017 by some selected Nsukka artists to authenticate the fact that Nsukka artists have taken a quantum leap beyond the frontiers of the human consciousness and in so doing, have mastered their oeuvres, bringing about great ingenuity and some unprecedented innovations in the execution of breath-taking postmodernist artworks whose formal contents and thematic probing interrogate germane issues.

Low-Light Photodetectors for Fluorescence Microscopy

Over the years, fluorescence microscopy has evolved and has become a necessary element of life science studies. Microscopy has elucidated biological processes in live cells and organisms, and also enabled tracking of biomolecules in real time. Development of highly sensitive photodetectors and light sources, in addition to the evolution of various illumination methods and fluorophores, has helped microscopy acquire single-molecule fluorescence sensitivity, enabling single-molecule fluorescence imaging and detection. Low-light photodetectors used in microscopy are classified into two categories: point photodetectors and wide-field photodetectors. Although point photodetectors, notably photomultiplier tubes (PMTs), have been commonly used in laser scanning microscopy (LSM) with a confocal illumination setup, wide-field photodetectors, such as electron-multiplying charge-coupled devices (EMCCDs) and scientific complementary metal-oxide-semiconductor (sCMOS) cameras have been used in fluorescence imaging. This review focuses on the former low-light point photodetectors and presents their fluorescence microscopy applications and recent progress. These photodetectors include conventional PMTs, single photon avalanche diodes (SPADs), hybrid photodetectors (HPDs), in addition to newly emerging photodetectors, such as silicon photomultipliers (SiPMs) (also known as multi-pixel photon counters (MPPCs)) and superconducting nanowire single photon detectors (SSPDs). In particular, this review shows distinctive features of HPD and application of HPD to wide-field single-molecule fluorescence detection.

Confocal imaging capacity on a widefield microscope using a spatial light modulator.

Confocal microscopes can reject out-of-focus and scattered light; however, widefield microscopes are far more common in biological laboratories due to their accessibility and lower cost. We report confocal imaging capacity on a widefield microscope by adding a spatial light modulator (SLM) and utilizing custom illumination and acquisition methods. We discuss our illumination strategy and compare several procedures for postprocessing the acquired image data. We assessed the performance of this system for rejecting out-of-focus light by comparing images taken at 1.4 NA using our widefield microscope, our SLM-enhanced setup, and a commercial confocal microscope. The optical sectioning capability, assessed on thin fluorescent film, was 0.85 ± 0.04 μm for our SLM-enhanced setup and 0.68 ± 0.04 μm for a confocal microscope, while a widefield microscope exhibited no sectioning capability. We demonstrate our setup by imaging the same set of neurons in C. elegans on widefield, SLM, and confocal microscopes. SLM enhancement greatly reduces background from the cell body, allowing visualization of dim fibers nearby. Our SLM-enhanced setup identified 96% of the dim neuronal fibers seen in confocal images while a widefield microscope only identified 50% of the same fibers. Our microscope add-on represents a very simple (2-component) and inexpensive (<$600) approach to enable widefield microscopes to optically section thick samples.

Accuracy of the fluorescence-aided identification technique (FIT) for detecting tooth-colored restorations utilizing different fluorescence-inducing devices: an ex vivo comparative study

ObjectivesThe aim of the present study was to compare the accuracy of the conventional illumination method (CONV) and the fluorescence-aided identification technique (FIT) for distinguishing between composite restorations and intact teeth using different fluorescence-inducing devices commonly used for FIT.Materials and methodsSix groups of six dentists equipped with one of six different FIT systems each independently attempted to identify composite restorations and intact teeth on a full-mouth model with 22 composite restorations using CONV and, 1 h later, FIT. The entire procedure was repeated 1 week later. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values, including 95% confidence intervals (CI), were calculated for CONV and FIT overall and for each device. The influence of examiner age, method, and device on each parameter was assessed by multivariate analysis of variance.ResultsThe sensitivity (84%, CI 81–86%), specificity (94%, CI 93–96%), PPV (92%, CI 90–94%), and NPV (90%, CI 88–91%) of FIT was significantly higher than that of CONV (47%, CI 44–50%; 82%, CI 79–84%; 66%, CI 62–69%, and 69%, CI 68–71%, respectively; p<0.001). The differences between CONV and FIT were significant for all parameters and FIT systems except VistaCam, which achieved no significant difference in specificity. Examiners younger than 40 years attained significantly higher sensitivity and negative predictive values than older examiners.ConclusionsFIT is more reliable for detecting composite restorations than the conventional illumination method.Clinical relevanceFIT can be considered an additional or alternative tool for improving the detection of composite restorations.

Time varied illumination laser speckle contrast imaging.

Laser speckle contrast imaging is a technique to determine blood flow rate with a limitation of low dynamic range. In this Letter, we introduce a varied illumination speckle contrast imaging method. It utilizes varying illumination during exposure to customize the correlation time (flow rate) to speckle contrast relation. The method can cover an order of magnitude larger range flow rate in a single exposure compared to constant illumination methods. The proposed method enables high dynamic range flow rate imaging, which is advantageous in studying larger vessels and small arteries. We demonstrate the theory by simulations and ex vivo and in vivo measurements.

Tuning the Baird Aromatic Triplet State Energy of Cyclooctatetraene to Maximize the Self-Healing Mechanism in Organic Fluorophores

Bright, photostable and non-toxic fluorescent contrast agents are critical for biological imaging. ‘Self-healing’ dyes, in which triplet states are intramolecularly quenched, enable fluorescence imaging by increasing fluorophore brightness and longevity, while simultaneously reducing the generation of reactive oxygen species that promote phototoxicity. Here, we systematically examine the self-healing mechanism in cyanine-class organic fluorophores spanning the visible spectrum. We show that the Baird aromatic triplet state energy of cyclooctatetraene can be physically altered to achieve order of magnitude enhancements in fluorophore brightness and signal-to-noise ratio both in the presence and absence of oxygen. We leverage these advances to achieve direct measurements of large-scale conformational dynamics within single molecules at sub-millisecond resolution using wide-field illumination and camera-based detection methods. These findings demonstrate the capacity to image functionally relevant conformational processes in biological systems in the kilohertz regime at physiological oxygen concentrations and shed important light on the multivariate parameters critical to self-healing organic fluorophore design (Pati et al., PNAS, 2020).

Characterization of Solar Cell by varying illumination

This work aims to confirm that the single-diode model of a monocrystalline cell can be used successfully also for thin-film solar cells when their basic parameters are calculated using the method of changing illumination. The authors describe the experimental procedure, in which I–V curves of thin-film solar cells are measured when illumination levels are changing. In experiments, a fully reflective 500 W solar simulator is used as an excellent broadband white light source, which provides the range of 0.01–10 Sun settings.

Facile and Scalable Synthesis of Si@void@C Embedded in Interconnected 3D Porous Carbon Architecture for High Performance Lithium‐Ion Batteries

AbstractSi‐based materials possess huge potential as an excellent anode material for Li‐ion batteries. However, how to realize scalable synthesis of Si‐based anode with a long cycling life and high‐performance is still a critical challenge. Here a water‐in‐oil microemulsion process followed by UV illumination, calcination, and hydrothermal method to produce yolk‐shell Si@void@C embedded in interconnected 3D porous carbon network architecture using silicon nanoparticles is reported. As a result, the sample Si@void@C/C‐2 electrode has achieved a reversible capacity of 1160 mA h g−1 at 0.2 A g−1 after 300 cycles and a stable long cycling life of 480 mA h g−1 at 1 A g−1 after 1000 cycles. A full battery with the synthesized anode shows a capacity of 128 mA h g−1 at 0.2 A g−1 as well as good cycling stability after 1100th cycles. Such excellent electrochemical performance is ascribed to its unique structure, the yolk‐shell void space, highly robust carbon shells and interconnected porous carbon nets that can improve the conductivity of the electrode, buffer the volume expansion, and also suppress Si nanoparticles stress variation. This water‐in oil system makes it possible for mass production of environmentally friendly synthesis of core–shell structure.

Application of the wavefield illumination method in a subthrust model in the Upper Magdalena Basin (Colombia)

Complex structures like subthrust show high risk during the definition of structural traps in low quality seismic images in depth, so we can use the structural interpretation to simulate the subthrust illumination by wavefield of a prospect area in order to reduce the uncertainty and support the oil exploration process. In general, we performed an exercise of 2D geophysical modeling using a wavefield illumination simulator. At first, we interpreted two geological models from a seismic line in depth. The geological interpretation was adjusted with information about structural styles in this part of Upper Magdalena Basin. Then, we use a velocity scenario and assign these velocities to both geological models. The wavefield illumination method allows us to see all of the wavepaths in the different pair of source-receivers in order to do a fast evaluation of the structure illumination. This could be used to improve the seismic acquisitions in structurally complex media.

Stopping Criterion during Rendering of Computer-Generated Images Based on SVD-Entropy.

The estimation of image quality and noise perception still remains an important issue in various image processing applications. It has also become a hot topic in the field of photo-realistic computer graphics where noise is inherent in the calculation process. Unlike natural-scene images, however, a reference image is not available for computer-generated images. Thus, classic methods to assess noise quantity and stopping criterion during the rendering process are not usable. This is particularly important in the case of global illumination methods based on stochastic techniques: They provide photo-realistic images which are, however, corrupted by stochastic noise. This noise can be reduced by increasing the number of paths, as proved by Monte Carlo theory, but the problem of finding the right number of paths that are required in order to ensure that human observers cannot perceive any noise is still open. Until now, the features taking part in the human evaluation of image quality and the remaining perceived noise are not precisely known. Synthetic image generation tends to be very expensive and the produced datasets are high-dimensional datasets. In that case, finding a stopping criterion using a learning framework is a challenging task. In this paper, a new method for characterizing computational noise for computer generated images is presented. The noise is represented by the entropy of the singular value decomposition of each block composing an image. These Singular Value Decomposition (SVD)-entropy values are then used as input to a recurrent neural network architecture model in order to extract image noise and in predicting a visual convergence threshold of different parts of any image. Thus a new no-reference image quality assessment is proposed using the relation between SVD-Entropy and perceptual quality, based on a sequence of distorted images. Experiments show that the proposed method, compared with experimental psycho-visual scores, demonstrates a good consistency between these scores and stopping criterion measures that we obtain.

Deep Dichromatic Guided Learning for Illuminant Estimation.

A new dichromatic illuminant estimation method using a deep neural network is proposed. Previous methods based on the dichromatic reflection model commonly suffer from inaccurate separation of specularity, thus being limited in their use in a real-world. Recent deep neural network-based methods have shown a significant improvement in the estimation of the illuminant color. However, why they succeed or fail is not explainable easily, because most of them estimate the illuminant color at the network output directly. To tackle these problems, the proposed architecture is designed to learn dichromatic planes and their confidences using a deep neural network with novel losses function. The illuminant color is estimated by a weighted least mean square of these planes. The proposed dichromatic guided learning not only achieves compelling results among state-of-the-art color constancy methods in standard real-world benchmark evaluations, but also provides a map to include color and regional contributions for illuminant estimation, which allow for an in-depth analysis of success and failure cases of illuminant estimation.

Phototransistor: The Story So Far

The research paper prospects the theory of phototransistor ranging from the history of the device to its application in the real world. The research paper deep dives into the characteristics of the phototransistor while discussing its dependence on bias drive, bias voltage, and illumination intensity. The research paper includes a comparative study between the various types of phototransistors based on optical gain, spectral range, and efficiency. It also concludes the best illumination method for the phototransistor based on the optical gain parameter.