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In this work we present a detector module based on large-area silicon photomultiplier, whose design has been optimized for time-domain diffuse optics measurements. In this application, to the best of our knowledge, it represents the largest area detector ever demonstrated, with expected breakthrough performance in terms of scattered light harvesting efficiency. It has been characterized using widely adopted protocols for performance assessment of instruments. We demonstrate the superior light harvesting capability and improved depth sensitivity, which can reach 4 cm. Moreover, the retrieval of optical properties has been demonstrated to be linear and with sufficient accuracy in the range corresponding to the human tissues. As a first step toward clinical application, we first performed in-vivo measurement at very large source-detector distances to show the suitability of the realized detector to tackle new challenges like lung or heart optical monitoring as well as imaging of deep cerebral function.

In contrast to the conventional monofacial photovoltaic (PV) modules, bifacial PV modules yield more electrical energy by utilizing the reflected or scattered light from the ground and surroundings. The energy generation efficiency of bifacial modules is determined by both the front-side and the rear-side output power. In this study, we compared the IV parameters as well as field performance of different module structures to further realize the influencing factors dominating the energy gain of bifacial modules. Our results show that the glass/glass bifacial modules encapsulated with bifacial solar cells provide over 6% more energy yield compared to the glass/backsheet monofacial modules encapsulated with regular monofacial solar cells. Due to optical enhanced effects of a reflective coating on the rear glass, the energy yield gain of bifacial modules can be increased to above 10%, even though the bifaciality factors were reduced from 72% to 64%. Our study indicates that enhancing the front-side output power of bifacial modules produces more benefits.

We developed a pendant-drop Raman spectrometer and observed cavity enhanced Raman scattered light. Further enhancement of the Raman scattered light was demonstrated by controlling the droplet shape...

We demonstrate the tunability of intensity and directionality of scattered light in a soft colloidal dielectric metamaterial. The system consists of high refractive index submicron-sized particles ...

Objectives Laser speckle flowgraphy is a technology using reflected scattered light for visualization of blood distribution, which can be used to measure relative velocity of blood flow easily without contact with the skin within a short time. It was hypothesized that laser speckle flowgraphy may be able to identify foot ischemia. This study was performed to determine whether laser speckle flowgraphy could distinguish between subjects with and without peripheral arterial disease. Materials and methods All subjects were classified based on clinical observations using the Rutherford classification: non-peripheral arterial disease, class 0; peripheral arterial disease group, class 2–5. Rutherford class 6 was one of the exclusion criteria. Laser speckle flowgraphy measured the beat strength of skin perfusion as an indicator of average dynamic cutaneous blood flow change synchronized with the heartbeat. The beat strength of skin perfusion indicates the strength of the heartbeat on the skin, and the heartbeat strength calculator in laser speckle flowgraphy uses the blood flow data to perform a Fourier transform to convert the temporal changes in blood flow to a power spectrum. A total of 33 subjects with peripheral arterial disease and 40 subjects without peripheral arterial disease at a single center were prospectively examined. Laser speckle flowgraphy was used to measure hallucal and thenar cutaneous blood flow, and the measurements were repeated three times. The hallucal and thenar index was defined as the ratio of beat strength of skin perfusion value on hallux/beat strength of skin perfusion value on ipsilateral thenar eminence. The Mann–Whitney U-test was used to compare the median values of hallucal and thenar index and ankle brachial index between the two groups. A receiver operating characteristic curve for hallucal and thenar index of beat strength of skin perfusion was plotted, and a cutoff point was set. The correlation between hallucal and thenar index of beat strength of skin perfusion and ankle brachial index was explored in all subjects, the hemodialysis group, and the non-hemodialysis (non-hemodialysis) group. Results The median value of the hallucal and thenar index of beat strength of skin perfusion was significantly different between subjects with and without peripheral arterial disease (0.27 vs. 0.87, respectively; P < 0.001). The median value of ankle brachial index was significantly different between subjects with and without peripheral arterial disease (0.8 vs. 1.1, respectively; P < 0.001). Based on the receiver operating characteristic of hallucal and thenar index, the cutoff was 0.4416 and the sensitivity, specificity, positive predictive value, and negative predictive value were 68.7%, 95%, 91.7%, and 77.6%, respectively. The correlation coefficients of all subjects, the hemodialysis group, and the non-hemodialysis group were 0.486, 0.102, and 0.743, respectively. Conclusions Laser speckle flowgraphy is a noninvasive, rapid, and widely applicable method. Laser speckle flowgraphy using hallucal and thenar index would be helpful to determine the differences between subjects with and without peripheral arterial disease. The correlation between hallucal and thenar index of beat strength of skin perfusion and ankle brachial index indicated that this index was especially useful in the non-hemodialysis group.

The rapid detection and classification of bacterial pathogens have great medical utility, and widespread applications in clinical labs, intensive care units, and infectious disease departments. The Rapid Bacterial Identification System (RBIS) is based on the principle of variation in light scattering when the laser beam passes through bacterial microbes. The use of laser light scattering and classification of binned plots algorithm gives a new dimension for real-time identification of different pathogens without any biochemical processing. Bacterium identification device consists of an assembly of photodetectors surrounded by the bacterial sample at different angles. The photodetectors acquire the scattered light in form of peaks when the laser beam passes by the sample. The acquired peak values were used to create 3D histograms to evaluate the frequency of occurrence. However, the identification is based on creating two dimensional binned plots with the help of the frequency of occurrence of peak values across two photodetectors. The algorithm of the system consists of two parts: Library files and the Comparator. Library files contain data of bacterial species in form of binned plots, while comparator compares the data of test sample with library files. The classification of sample depends on the maximum resemblance of the number of binned plots with library files. The classification of Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli gives mean accuracies of 81.8%, 70.9%, and 71.4 %, respectively. The proposed system can be applied to future real-time intelligent theranostic systems for diagnosis and treatment of pathogenic diseases.

Chronic venous insufficiency is often accompanied by trophic changes in soft tissues. The treatment of such patients is long and often, ineffective. Relapse of a trophic ulcer is about 30% and leads to deterioration of life quality and dissatisfaction with conservative and even surgical treatment. Goal. Objectification of changes in the microvasculature and compensatory the possibilities of collateral circulation in the lower extremities with complicated forms of chronic venous insufficiency. Materials and methods. The studies were carried out on the Linsor installation characterizing the biological tissue by the change of scattered light intensity and on the thermal imager making possible to determine the temperature of a point with an accuracy of 0,001 degrees, followed by software image processing. The examination was performed 3-4 times in the dynamics of the treatment process and before the patient discharge, from a standard distance of 1,5 meters. The soft tissues in 23 patients with chronic venous insufficiency of the lower extremities and the presence of open trophic ulcers was studied. There were 21 women, 2 men, the average age was 45,2±3,6 years. The area of the ulcer defect varied from 5,7 cm² to 15,3 cm². Patients with extensive trophic ulcers (circular) were excluded from the examination, because of absence of ulcer defect epithelization during the period of hospitalization and its visualization by the thermographic method. Results. As a result of the study, we obtained a reduced intensity of infrared radiation of the ulcer surface in all patients. To clearly isolate ulcerative defect from the surrounding tissues, we set the temperature range 35,0–37,5 °C and recalculated the resulting area in cm² (conversion factor 22,73). We studied the microcirculatory changes occurring in the trophic ulcer and surrounding tissues, confirming the need to continue conservative treatment after complete ulcer defect epithelization for at least 7 days, and only after that period the normalized level of infrared radiation was detected and subsequently relapsed trophic ulcers did not occur for a long time. Conclusion. Based on the obtained data, we confirmed the thermal imaging method sensitivity is suitable for assess of microcirculation in the trophic ulcer area; the method provides the possibility to apply it for the dynamics of conservative treatment in patients with complicated forms of chronic venous insufficiency.

Multiplex detection of microRNAs is highly desirable in trace analysis of clinical samples for early-stage disease diagnosis. In the present study, we report a new liquid suspension nano-chip technology for multiplex detection of microRNAs by detecting side scatter and fluorescence signals of molecular beacon-modified polystyrene nanoparticles, simultaneously. Polystyrene nanoparticles were encoded by distinguished intensity of scattered light with tunable sizes (120 nm, 200 nm and 280 nm). In the proposed detection system, the fluorescence of 5-carboxyfluorescein was recovered due to the structure change of molecular beacons from hairpin to rod-like shape caused by the hybridization of target microRNAs. The well-designed liquid suspension nano-chip system enabled quantitative detection of three colorectal cancer-related microRNAs with low limits of detection and high sensitivity. More importantly, for simulated clinical samples, three random mixed microRNAs were simultaneously detected by accurately decoding the scattering intensity of polystyrene nanoparticles of different sizes and quantitatively analyzed by fluorescence intensity. This technology provides a washing-free, sensitive, convenient and small loading volume strategy for detecting clinical multiplex nucleic acid samples.

The possibility of determining the structural and biophysical parameters of skin from the spectra of scattered light is assessed. Schemes for measurement of the coefficient of diffuse reflection, the coefficient of brightness back-scattered by biological tissue, and the spatial illumination at some distance from the source are examined. Algorithms are proposed for establishing the volume concentrations of melanine and blood vessels, the thickness of the epidermis, the degree of oxygenation of the blood, and the average diameter of the capillaries. It is shown that the first two schemes give approximately identical characteristics for solution of the inverse problem, although the polarization measurements are somewhat less susceptible to experimental error. Analysis of such similarity has demonstrated that it is due to features of the optical characteristics of the skin layers. The preferred method is the third experimental scheme, which is not subject of error and has substantially higher sensitivity to the degree of oxygenation of the blood and the average diameter of the capillaries and makes it possible to establish all the desired parameters of the skin with acceptable accuracy for practical purposes.

Spatially offset Raman spectroscopy (SORS) offers the prospect of collecting spectral information detailing the molecular composition of biomaterials at greater depths below the surface layers than are normally probed by conventional Raman spectroscopy. By collecting off-axial scattered light, the technique overcomes the large background from in-line light within scattering media. In this paper we present a configuration which enables the highly efficient collection of spectral markers, indicative of bone health, including Raman signatures to assess phosphate, collagen and carbonate content, at millimeter depths. We demonstrate the effectiveness of the technique by performing spectral decompositions to analyze the molecular distribution of these markers non-invasively, using in vitro model systems, comprising bone and tissue, in situ.

One of the most important research topic in optics and photonics is the design of metasurfaces to substitute conventional optical elements that demonstrate unprecedented merits in terms of performance and form factor. In this context, full-space control of metasurfaces that makes it possible to manipulate scattered light in transmission and reflection spaces simultaneously, is proposed as the next-generation scheme in optics, with a potential for applications such as 360° holographic images and novel optical systems. However, previously designed metasurfaces lacked functionality because the desired operation occurs under preconditioned light; therefore, they are difficult to use in real applications. Here, we present a design method that enables polarization-dependent full-space control, in which two independent and arbitrary phase profiles can be addressed to each space. Upon introducing a phase gradient value to realize the critical angle condition, conversion of transmissive into reflective operation is realized. Then, rectangular nanopillars are utilized to facilitate polarization beam splitting with the desired phase. Three samples were fabricated and measured based on the proposed scheme.

Laser beam propagation in highly scattering media has attracted much attention for optical sensing fields because the propagation of the light is often limited to the near-surface regions of the media. To increase the sensing capability in such scattering conditions, we focus on the propagation property of an annular beam in a highly scattering media. In our previous work, the non-diffractive beam was generated by propagating an annular beam in a scattering medium of colloidal suspension (diluted milk) up to the concentration of 22%, which is near the human tissue. In this study, the propagation property of a partially blocked annular beam using a fan-like obstacle with different apex angles is investigated to realize object detection in highly scattering media such as human tissue, fog, or cloud. Simulation results show that non-diffractive beams can be generated when partially blocked annular beam with blocking angle from 0° to 30o is propagated in free space. The propagation experiment of partially blocked annular beam in scattering media shows that the center peak intensity in scattered light is detected when the apex angle is set up to 30° . By measuring scattered light at different receiving distances, the experiment results show that the center peak is kept at a certain distance away from the optical cell. This result verifies that the central peak intensity of this scattered light is a non-diffractive beam.

Here we present a methodology to characterize the light intensity fluctuations that arise from rotations of individual granular particles. We describe a setup for dynamic light scattering measurements on individual macroscopic particles and isolate the contribution from rotations of the individual particles to the obtained correlation functions. The results show that rotation of granular particles results in a significant contribution to scattered light intensity fluctuations, a phenomenon not considered so far in dynamic light scattering measurements on fluidized granular media. The results presented here may thus form the basis for an extended light scattering methodology for granular media, and improve the selection of granular particles according to their dynamic light scattering signal.

Measuring the aberrations of optical systems is an essential step in the fabrication of high precision optical components. Such a characterization is usually based on comparing the device under investigation with a calibrated reference object. However, when working at the cutting-edge of technology, it is increasingly difficult to provide an even better or well-known reference device. In this manuscript we present a method for the characterization of high numerical aperture microscope objectives, functioning without the need of calibrated reference optics. The technique constitutes a nanoparticle, acting as a dipole-like scatterer, that is placed in the focal volume of the microscope objective. The light that is scattered by the particle can be measured individually and serves as the reference wave in our system. Utilizing the well-characterized scattered light as nearly perfect reference wave is the main idea behind this manuscript., An absolute characterization technique for microscope objectives is presented, working without a calibrated reference element. To achieve this, a reference wave is created by a sub-wavelength object.

We experimentally demonstrated the surface plasmon propagation of crystalline silver nanowire excited by fluorescence of quantum dots. The scattered light origin from SPR was observed at one end of nanowire when the linear-polarized excitation light was focused onto another end.

Light scattered from optical components is a source of critical noise for interferometric gravitational wave detectors. We show how balanced low coherence interferometry allows the ultra-low amount (-120 dB) of light coherently back-reflected or back-scattered by optical components to be accurately measured.

Imaging flow cytometry (IFC) produces up to 12 different information-rich images of single cells at a throughput of 5000 cells per second. Yet often, cell populations are still studied using manual gating, a technique that has several drawbacks. Firstly, it is hard to reproduce. Secondly, it is subjective and biased. And thirdly, it is time-consuming for large experiments. Therefore, it would be advantageous to replace manual gating with an automated process, which could be based on stain-free measurements originating from the brightfield and darkfield image channels. To realise this potential, advanced data analysis methods are required, in particular, machine learning. Previous works have successfully tested this approach on cell cycle phase classification with both a classical machine learning approach based on manually engineered features, and a deep learning approach. In this work, we compare both approaches extensively on the complex problem of white blood cell classification. Four human whole blood samples were assayed on an ImageStream-X MK II imaging flow cytometer. Two samples were stained for the identification of 8 white blood cell types, while two other sample sets were stained for the identification of resting and active eosinophils. For both datasets, four machine learning classifiers were evaluated on stain-free imagery using stratified 5-fold cross-validation. On the white blood cell dataset the best obtained results were 0.776 and 0.697 balanced accuracy for classical machine learning and deep learning, respectively. On the eosinophil dataset this was 0.866 and 0.867 balanced accuracy. From the experiments we conclude that classifying distinct cell types based on only stain-free images is possible with these techniques. However, both approaches did not always succeed in making reliable cell subtype classifications. Also, depending on the cell type, we find that even though the deep learning approach requires less expert input, it performs on par with a classical approach.

Vertical-cavity surface-emitting laser (VCSEL) devices operate using a variety of viewing angles to satisfy the demands of different applications. One simple and universal approach to accomplish this is by using scattering elements in the packaging process for VCSEL chips. However, inevitable backward scattering loss is introduced, which suppresses the radiant efficacy of VCSEL devices. Therefore, we have proposed an enhanced specular reflection (ESR) structure with an opening circle window (OCW) to recycle the backward scattered light. The ray-tracing method is used to optimize the diameter of the OCW, as well as the thickness of the ESR structure. Furthermore, the light extraction mechanism is discussed. According to theoretical results, VCSEL devices with optimized ESR structures are fabricated and compared with traditional VCSEL devices. The experiment results demonstrate that ESR structures can significantly enhance the radiant efficacy of VCSEL devices using scattering elements. This shows great potential for applications involving illumination and 3-D imaging.

The striking structural colour originated from photonic crystals (PCs) self-assembled with specific nanospheres has been applied in various industries. Structural chromogen with lifelike manifestations is also expected to become a novel colouration technology for textiles. However, the contrast of structural colour is usually affected by scattered light generated from nanospheres. In order to obtain high contrast structural colour on fabric substrates, the melanin-like nanospheres were prepared and applied to fabricate PCs on white fabric surface. The melanin-like PS@PDA nanospheres showed smooth surface and perfect sphericity, which assured the self-assembly of melanin-like nanospheres to form well-organized face-centred cubic and regularly close-packed arrays to exhibit brilliant structural colour. In addition, the phenomenon of double-sides structural colouration of fabric was explained via analysing the driving force of self-assembly of nanospheres in dispersion solution. It is found that the melanin-like nanospheres can replace black substrate to achieve high contrast structural colour on white fabric substrate and simplify the process of structural colouration of textiles because the dyeing process of fabric can be omitted. The feasible technique would promote the practical application of structural colour in textile field.

Kelvin wake is one of the common wakes generated by moving ships and contains rich information about ships. In this paper, free wave elevations of Kelvin wake are calculated based on the Michell thin ship theory combined with a point source perturbation model. The probability density function of sea surface slopes is introduced to calculate the specular reflection of sunlight and skylight and the refraction of scattered light underwater. Satellite-detected Kelvin wakes are then simulated by adding surface specular reflectance and water-leaving reflectance. Simulation results agree well with satellite measurements. The specular reflection of sunlight is the decisive factor affecting the features of Kelvin wakes according to the simulation results. The main factors that influence the specular reflection of sunlight, such as the incident direction and observation direction, ship parameters, and background environment, are discussed. This study is helpful for wake detection and provides a preliminary theoretical method for the retrieval of ship information.

Tofu is an ancient soybean product that is produced by heating soymilk containing a coagulation agent. Owing to its benefits to human health, it has become popular all over the world. An important index that determines the final product&rsquo, s (tofu&rsquo, s) quality is firmness. Coagulants such as CaSO4 and MgCl2 affect the firmness. With the increasing demand for tofu, a monitoring methodology that ensures high-quality tofu is needed. In our previous paper, an opportunity to monitor changes in the physical properties of soymilk by studying its optical properties during the coagulation process was implied. To ensure this possibility, whether soymilk and tofu can be discriminated via their optical properties should be examined. In this study, a He&ndash, Ne laser (Thorlabs Japan Inc., Tokyo, Japan, 2015) with a wavelength of 633 nm was emitted to soymilk and tofu. The images of the scattered light on their surfaces were discriminated using a type of deep learning technique. As a result, the images were classified with an accuracy of about 99%. We adjusted the network architecture and hyperparameters for the learning, and this contributed to the successful classification. The construction of a network that is specific to our task led to the successful classification result. In addition to this monitoring method of the tofu coagulation process, the classification methodology in this study is worth noting for possible use in many relevant agricultural fields.

An optical standing-wave interferometer using a polarization technique for displacement measurement is proposed. An ultra-thin scattering plate is inserted into the optical standing-wave field, which is built by the interference of the forward- and backward-propagating light beams. By means of detecting the phase variations of the scattered light from the scattering plate with the polarization phase quadrature technique, the displacement can be determined precisely. The experimental results demonstrate that this polarization-standing-wave interferometer can measure displacement on a scale of tens of millimeters with nanometer-scale resolution. The periodic nonlinear error caused by the multi-beam interference is also detailed.

To safely handle hydrogen as an energy carrier, it is important to understand the behaviour of hydrogen. There are many methods available for measuring hydrogen concentration using conventional sensors; however, it is difficult to detect hydrogen gas from a distance. Here, we observed hydrogen behaviour over a narrow region of space with a Raman scattered light sensor. Generally, there is some delay in conventional sensors; however, there was almost no delay with the use of our sensor. We used 1- and 6-mm diameter holes as spout nozzles to change the initial velocities. To confirm the effectiveness of our method, we used hydrogen visualization sheets, which became transparent when hydrogen was detected enabling the hydrogen movement to be visualized. Hence, we observed the behaviour of hydrogen gas in a small container and optimized the device to increase the measurement distance from 4.5 to 7.5 m.

In this paper, we systematically studied the scattered light when the stripe beam of ordinary polarized light and extraordinary polarized light are incident to the LiNbO3:Fe crystal, respectively. First, we observed the variation of scattered light with the different angle between the stripe beam and the c-axis. And find the scattered light is growing with time along the c-axis direction of the crystal when the e-light is incident; while the scattered light is growing along a special direction which is not the c-axis direction or the stripe direction, when o-light is incident to the crystal. Then we analyzed the causes of these phenomena. In addition, we also studied the diffraction efficiency of o-light and e-light, and the raster image in the crystal.

The effect of scattering on the transmission of subwavelength Si nanorod arrays is investigated. It is found that the distance between the nanorods has important effect on the transmission because the scattered light varies largely with it. When the nanorods are close to each other, the back-scattered light and the light reflected by the surface of substrates interfere destructively and lead to a high transmission. When the distance of the nanorods increases, the intensity of the scattered light decrease and this makes the transmission decrease. The reflection and the transmission of the nanorod arrays can be adjusted by changing the distance between the neighbouring nanorods.

Purpose: To evaluate the optical quality and tear-film dynamics in patients with aqueous-deficient or evaporative subtype of dry eye disease (DED). Methods: Twenty-five aqueous-deficient dry eye (ADDE) patients, 25 DED patients with meibomian gland dysfunction (MGD), and 25 healthy subjects were included in this study. Vision-related health-targeted quality of life was evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Dynamic recording with a double-pass system (Optical Quality Analysis System [OQAS]) was performed in right eyes. Scattered light was measured as the objective scatter index (OSI) at 0.5-second intervals over 20 seconds without blinking. Then, we recorded OSI every 0.5 seconds within a 20-second period with the subjects asked to blink freely. Several parameters were established to evaluate the dynamic alterations of optical quality and the effects of blinks: OSI, OSI standard deviation (SD), ΔOSI, ΔOSI/time, blinking change (BC), and blinking frequency (BF). Additional clinical examination included tear film break-up time (BUT), Schirmer I test (SIT), fluorescein staining grade (FL), meibomian gland quality, meibomian gland expressibility, and meibomian gland drop-out. Results: The OSI, SD, ΔOSI, ΔOSI/time, BC, and BF were significantly higher in DED patients than controls (P < 0.01, respectively). The OSI, SD, ΔOSI, ΔOSI/time, BC, and BF were significantly higher in patients with MGD than patients with ADDE (P < 0.01). In the MGD group, BUT, FL staining score, lid abnormality, meibomian gland expressibility, and meibomian gland drop-out were correlated with Δ OSI and Δ OSI/time. Conclusion: Dry eye patients with MGD had significant alterations of optical quality compared with ADDE patients. The double-pass system has potential to be a useful quantitative method to evaluate the optical quality and tear-film dynamics in patients with dry eye.

Degraded visual environments like fog pose a major challenge to safety and security because light is scattered by tiny particles. We show that by interpreting the scattered light it is possible to detect, localize, and characterize objects normally hidden in fog. First, a computationally efficient light transport model is presented that accounts for the light reflected and blocked by an opaque object. Then, statistical detection is demonstrated for a specified false alarm rate using the Neyman-Pearson lemma. Finally, object localization and characterization are implemented using the maximum likelihood estimate. These capabilities are being tested at the Sandia National Laboratory Fog Chamber Facility.

A method for the measurement of the shape of a fine structure beyond the diffraction limit based on speckle interferometry has been reported. In this paper, the mechanism for measuring the shape of the fine structure in speckle interferometry using scattered light as the illumination light is discussed. Furthermore, by analyzing the phase distribution of the scattered light from the surface of the measured object, this method can be used to measure the shapes of periodic structures and single silica microspheres beyond the diffraction limit.

International audience; Interferometry is often used as a means for providing high sensitivity measurements. But interferometric measurements can also be easily affected by coherent stray light. In many fields, a correct estimation of the amount of stray light is necessary to assess the system performances and to guide the choice of the correct design. The LISA (Laser Interferometer Space Antenna) mission will consist of three spacecraft orbiting the Sun in a triangle constellation with arms of 2.5 Mkm to detect gravitational waves. Detection is carried on thanks to two laser beams emitted by each spacecraft towards the two remote ones. A tiny fraction of the emitted beams is collected by the telescopes in the distant spacecrafts and interfered with the local laser beam, giving six heterodyne phase readouts which carry the imprint of the gravitational wave. Given the goal of reaching a noise floor of a few picometers on the distance measurement, this configuration will be very sensitive to stray light noise and for this reason stray light estimates are an important part of the design process. For a complex optical system stray light simulations can be made with specific optical analysis software (FRED, Zemax,...) which require expensive licences and computational time. To have a quick estimate one can try some manual calculation, but it is not always easy to find which scattering or reflection directions will lead to stray light able to couple into the interferometric measurement, not only with good superposition, but also with matching wavefront. We’ll use the divergence of the laser beam to estimate the angular aperture under which a scattering element in the optical system can direct stray light into a detector, and show how these simple considerations can lead to stray light estimates which are in good agreement with the most advanced software simulations. These considerations are applicable to various optical systems.

Unwanted background fluorescence in microscopy can occur when light from fluorescent structures scatters against nearby tissues. Bright cell bodies produce haze that mask nearby dim structures, including neuronal fibers. We have developed a method to eliminate this haze by fitting it to a simple function. This method enables clearer post-imaging visualization of axons in our in vivo imaging of neurons. We are investigating ways to increase the computation speed of our background fitting technique to allow for real-time image improvement. The implementation of our method in real-time imaging will broaden the potential applications of this fitting method.

We present a novel Brillouin fibre probe to achieve background-free remote mapping of micromechanical properties in tissue-mimicking hydrogel-water phantom. This Brillouin imaging system is designed using a low loss hollow core optical fibre and miniature objective for efficient light delivery and scattered light collection. The system efficiency and focusing power is comparable to free space Brillouin optical systems. This demonstration paves the way towards a wide range of biomedical and bioengineering applications where non-contact, label-free and damage-free mechanical imaging is required to retrieve in situ and in vivo microscopic viscoelastic properties of tissues and biomaterials.

The optical quality of intraocular lenses (IOLs) of different materials that have been implanted from 16 to 44 years in human eyes was studied. The IOLs were explanted due to other causes than loss of transparency. The scattered light from the IOLs was assessed in two angular regimes by using dark field images (for wide angles) and the optical integration method (for narrower angles). No evident differences were found in the scattering intensities processed from the dark images. The explanted lenses presented slightly increased amounts of straylight between 1 and 5.1° when compared to a reference new unused lens.

Dynamic light reflection can serve a similar purpose to tools such as digital line processing devices. It is interesting, therefore, that evidence of dynamic light reflection can also be found in the animal kingdom and that there may be alternative ways of actuating light control. This study discovered that several features contained in the heads of hardyhead silverside fish, particularly around the edges of the iris, caused blinking using environmentally scattered light. Analyzing the blinking using recorded video of the fish iris revealed that circular cells existing in the iris changed their light intensity at 2 Hz. These 5–10-μm-diameter cells are normally blue. However, it is found that a distinct light intensity changed in 0.04 seconds, and additional green and yellow colors overlapped with the blue. It is hoped that utilizing the mechanism that controls the rapid changes in light intensity using only environmental lighting can reduce electrical power usage in display devices.

Under the irradiation of laser, biological particles emit fluorescence and scattered light. The spectral signals composed of fluorescence and scattered light can be used to classify and recognize biological particles. The acquisition of these two kinds of optical signals needs to be converted into electrical signals for acquisition. For this electrical signal, A/D converter with extremely fast speed is needed. In the data acquisition process, ZYNQ is used to select and classify the collected signals, and the classified data is displayed on the LCD screen.

Advanced Virgo end benches were a significant source of scattered light noise during the third observing run that lasted from April 1 2019 until March 27 2020. We describe how that noise could be subtracted using auxiliary channels during the online strain data reconstruction. We model in detail the scattered light noise coupling and demonstrate that further noise subtraction can be achieved. We also show that the fitted model parameters can be used to optically characterized the interferometer and in particular provide a novel way of establishing an absolute calibration of the detector strain data., 12 pages, 5 figures, Accepted in Class. Quantum Grav

In this study, a faster water turbidity measurement system based on simultaneous measurement of transmitted and forward scattered light using an optical CCD line sensor is presented. The turbidity measurement results obtained at 650 nm for varying distilled and tap water-NaCl solutions are given. The impact of 10° and 90° -forward scattered light measurements on the dynamic range was also discussed using a generic transmitted/forward scattered light measurement setup. The results of the proposed CCD line sensor system were calibrated with the turbidity measurements realized using two different commercial devices measuring in NTU (Nephelometric Turbidity Unit) and TDS (Total Dissolved Solids) units. The results have shown that a higher dynamic range could be obtained with 10° -forward scattered light measurements. Also, a balanced rapid water turbidity measurement for a range of 0–30 NTU was experimentally demonstrated using a single LD-CCD line sensor system. © 2021 Elsevier GmbH

Dynamic light scattering (DLS) is widely used for the characterization of the size distributions of polymers and nanoparticles in dispersions. The time correlation function of the scattered light intensity can be calculated from the intensity fluctuation with time and converted into the size of the scatterers. It has been difficult to apply DLS to a dispersion containing large pollutant particles, however, because the pollutants moving in the dispersion can give rise to intense noise signals from time to time during data acquisition. In conventional DLS, this type of noise renders the entire measurement useless. Here we report a novel software-based DLS system in which the arrival times of all the scattered photons are recorded using a time-to-digital converter, and the time correlation function is calculated exclusively from the uncontaminated parts of the data in post-processing. We demonstrate the validity of this noise reduction scheme by evaluating the silica nanoparticle size in a dispersion containing a small number of micrometer-sized PMMA particles as a model contaminant.

Propagation of light through random scattering medium scrambles information and generates randomness. This paper covers some of our works towards measuring incident light modes from the random pattern.

We describe a technique to measure the position of a dipolar scatterer based on self-homodyne detection of the scattered light. The method can theoretically reach the Heisenberg limit, at which information gained about the position is constrained only by the back-action of the scattered light. The technique has applications in the fields of levitated optomechanics and trapped ions and is generally applicable to the position determination of confined light scatterers., Comment: 11 pages, 5 figures

We report on an expanded catalog of total reflectance measurements of various common (and uncommon) materials used in the construction and/or baffling of optical systems. Total reflectance is measured over a broad wavelength range (250 nm < λ

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 (

The first twenty years of operation of gravitational-wave interferometers have shown that these detectors are affected by physical disturbances from the surrounding environment. These are seismic, acoustic, or electromagnetic disturbances that are mainly produced by the experiment infrastructure itself. Ambient noise can limit the interferometer sensitivity or potentially generate transients of non-astrophysical origin. Between 1 April 2019 and 27 March 2020, the network of second generation interferometers&mdash, LIGO, Virgo and GEO&mdash, performed the third joined observing run, named O3, searching for gravitational signals from the deep universe. A thorough investigation has been done on each detector before and during data taking in order to optimize its sensitivity and duty cycle. In this paper, we first revisit typical sources of environmental noise and their coupling paths, and we then describe investigation methods and tools. Finally, we illustrate applications of these methods in the hunt for environmental noise at the Virgo interferometer during the O3 run and its preparation phase. In particular, we highlight investigation techniques that might be useful for the next observing runs and the future generation of terrestrial interferometers.

Color uniformity is one of the essentials for the on-going development of WLED. To achieve a high color uniformity index, increasing the scattering events within the phosphor layers was reported to be the most efficient method and in this article, ZnO is the chosen material to apply in this method. After analyzing the scattering properties through the scattering cross-section 𝐶𝑠𝑐𝑎(𝐷,𝜆), scattering coefficient 𝜇𝑠𝑐𝑎(𝜆) and scattering phase function 𝜌(𝜃,𝜆), the which outcomes comfirm that ZnO can enhance the scattered light in the phosphor layers. Moreover, the findings from the study of ZnO concentration from 2% to 26% suggest that color uniformity also depends on the fluctuation of ZnO concentration, therefore, to control color uniformity the focus should be implied on both size and concentration of ZnO. The experimental results from this research show that the luminous flux of WLED is at the peak if the concentration of ZnO is at 6%, and when the concentration of ZnO is at 18% and has 100 nm particles size, the ΔCCT reaches the lowest level. The final choice should be based on the desired characteristic of WLEDs, however, if the WLED need to excel in both luminous flux and ΔCCT then 6% ZnO concentration with particles size from 100 nm-300 nm is the optimal choice.

Imaging of scenes using light or other wave phenomena is subject to the diffraction limit. The spatial profile of a wave propagating between a scene and the imaging system is distorted by diffraction resulting in a loss of resolution that is proportional with traveled distance. We show here that it is possible to reconstruct sparse scenes from the temporal profile of the wave-front using only one spatial pixel or a spatial average. The temporal profile of the wave is not affected by diffraction yielding an imaging method that can in theory achieve wavelength scale resolution independent of distance from the scene.

on behalf of the LISA-France collaboration; International audience; Scattered light can disrupt heterodyne measurements in the ZIFO test bench for LISAmission. This study shows a method to find all possible scattering paths and calculate their power, confirming the feasibility of the system.

Different scattering processes take place when photons propagate inside turbid media. Many powerful experimental techniques exploiting these processes have been developed and applied over the years in a large variety of situations from fundamental and applied research to industrial applications. In the present paper, we intend to take advantage of Static Light Scattering (SLS), Dynamic Light Scattering (DLS), and Time-Resolved Transmittance (TRT) for investigating all the different scattering regimes by using scattering suspensions in a very large range of scatterer concentrations. The suspensions were prepared using Intralipid 20%, a material largely employed in studies of the optical properties of turbid media, with concentrations from 10&minus, 5% to 50%. By the analysis of the angular and temporal dependence of the scattered light, a more reliable description of the scattering process occurring in these samples can be obtained. TRT measurements allowed us to obtain information on the reduced scattering coefficient, an important parameter largely used in the description of the optical properties of turbid media. TRT was also employed for the detection of inclusions embedded in Intralipid suspensions, by using a properly designed data analysis. The present study allowed us to better elucidate the dependence of scattering properties of Intralipid suspensions in a very large concentration range and the occurrence of the different scattering processes involved in the propagation of light in turbid media for the first time to our knowledge. In so doing, the complementary contribution of SLS, DLS, and TRT in the characterization of turbid media from an optical and structural point of view is strongly evidenced.

We report on a damage-less singulation technique using Stealth Dicing (SD) of ultra-thin wafers. This paper describes how we minimized the damage using highly sensitive Test Element Group (TEG) wafers with patterned aluminum lines. We developed a TEG wafer, having multiple wiring lines of Ti/Al layers, to monitor laser damage. The wiring lines were designed so that a change in wiring resistance caused by scattered light could be measured. Also, in order to measure the position of the generated scatter damage, the line/space ratio (L/S) of the monitor wiring was designed to be 1 μm/1 μm. In this experiment, IR-OBIRCH and STEM analyses were performed to identify the details of the laser damage on the wiring. In addition, two types of lasers (wavelengths: 1099 nm and 1342 nm) were used to evaluate the effect of the transmittance in silicon on the processing results. Laser damage evaluation was carried out on the basis of parameters such as the laser processing power and laser focus position (distance from the device side). We confirmed that laser damage was prevented and that damage-free singulation could be achieved by optimizing the processing conditions using a laser with a wavelength of 1099 nm. By applying this SD technology, the width of the dicing street can be shrunk to 1/4 compared with the conventional blade dicing.