Diffuse Reflectance Characteristics Research Articles

Back to Michelson interferometer: a precise inspection system for industrial intricate structures defect detection

Quality inspection of injection molding products with intricate three-dimensional structures and diffuse reflection characteristics is a very important procedure in industrial production. However, the current inspection process for these products still heavily relies on visual inspection, which introduces various issues including low efficiency, and missing or false detection. While previous studies have utilized deep-learning methods in conjunction with specific optical sensors and imaging systems to detect defects, the intricate structure of injection molding products and the small magnitude of defects pose significant challenges in defect detection. To address these challenges, this paper proposes an inspection system based on Michelson interferometer capable of detecting and characterizing defects of injection molding products. Notably, by utilizing the light intensity modulation and an improved image differencing approach, this inspection system is capable of detecting defects with a magnitude as small as 0.1 mm and achieving a remarkable detection accuracy exceeding 93% on self-made datasets without utilizing phase information. The effectiveness of our method is validated by comparison with mainstream deep-learning-based defect detection methods and visual inspection methods.

Quantitative phase analysis and hyperspectral imaging for the automatic identification of veins and blood perfusion maps

IntroductionMedical workers commonly physically identify subcutaneous veins to locate a suitable vesselto implant a catheter for drug administration or blood sample. The general rule of thumb is to locate a big, clean vein that will allow the medication to readily pass within the intended blood vessel. Peripheral problematic venous access happens when a patient's veins are difficult to palpate because of factors like dark skin tone, edema or excess tissue. The ability to see how the vasculature changes to support the therapeutic methods without damaging the surrounding tissue is another challenge. Materials and methodsHyperspectral imaging (HI) is a developing technique with several potential uses in medicine. Using its spectroscopic data, veins and arterioles could be noninvasively detected and discriminated. It is frequently important to use quantitative phase analysis for vein localization. To assess hyperspectral image data for the detection of both veins and peripheral arteries, we suggest using an advanced image processing and classification algorithm based on the phase information related to the index of refraction change and associated scattering. We show that this need may be satisfied using quantitative phase imaging of forearm skin tissue at different depths. ResultsTo demonstrate the variations in the diffuse reflectance characteristics between skin surface and veins, phase resolved pictures were successfully produced for twelve volunteers using our imaging methodology. We found that the skin surface details are completely apparent at the unique wavelength of 441 nm. The 500-nm wavelength was the most efficient for grouping peripheral arteries and illuminating the blood perfusion maps. Using our HI experimental setup and our phase imaging procedure on the 600 nm and 650 nm visible spectral pictures, we were able to properly describe the vein map. This spectral area may be utilized as a vein locator marker which could approximately reach till 3 mm depth under skin surface. ConclusionsInitial findings suggested that our imaging technique would be able to assist medical examiners in safely assessing the veins and arteriole's locations automatically without exposing the skin to infrared radiation. Meanwhile, our pilot research in this work to determine the best spectral wavelengths for localizing veins and mapping blood perfusion using our phase analysis imaging strategy with the HI camera. By substituting the HI camera with a custom conventional RGB camera that only functions at specific wavelengths during the discovering of blood perfusion locations or prior to intravenous catheterization, a distinctive and efficient system for precise identification may be developed to serve in the field of the vascular therapeutic methods.

Preparation of In-doped SnO2 hollow spheres and the solar-heat insulation properties of polyvinylidene fluoride film containing prepared spheres

In-doped SnO2 hollow spheres of submicron size were prepared with carbon ball substrate via the hydrothermal method and heat treatment process. The micromorphology and microstructure of the spheres were examined with XRD, SEM, EDS and TEM. And their absorption and diffuse reflection characteristics were also characterized. The prepared spheres were then introduced to polyvinylidene fluoride (PVDF) to form composite films with the spin coater. UV-Vis-NIR spectrophotometer and confined thermal insulation device were used to study the optical and solar-heat insulation properties of the film, respectively. The results show that In3+ doping increases the lattice constant, results in lattice distortion, generates oxygen vacancies and narrows the forbidden band, leading to significant increase in the diffuse reflectance of PVDF film in the visible and infrared regions. Moreover, In3+ doping has no negative effect on the high transmittance of SnO2, and the hollow structure of SnO2 is beneficial to the heat insulation of PVDF film. In addition, when the loading content of SnO2 spheres is in a range of 15–25 wt%, the thermal conductivity and heat insulation performance of the PVDF film show little change, possibly caused by local agglomeration. This study indicates that PVDF film containing In-doped SnO2 hollow spheres is a promising material for energy conservation.

Utilization of gold nanoparticles for the detection of squamous cell carcinoma of the tongue based on laser-induced fluorescence and diffuse reflectance characteristics: an in vitro study

Squamous cell carcinoma is a very common type of oral cancer that affects the health of people with an unacceptably high mortality rate attributed to the difficulties in detecting the disease at an early stage. Therefore, effective techniques for early diagnosis and effective therapy of oral cancer are necessary. In the present study, we exploit the ability of gold nanoparticles (AuNPs) to undergo coupled surface plasmon resonance when closely spaced to improve diagnosing squamous cell carcinoma of the tongue. The prepared AuNPs are characterized by UV–VIS spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy. The size of the prepared AuNPs is 12 ± 2 nm with narrow size distributions and exhibited high stability with a zeta potential of − 16.5 mV. The light fluorescence of the normal and cancer cells is recorded before and after NP addition using a spectrometer upon excitation by 405-nm laser irradiation. Furthermore, the light reflectance of the examined samples is measured at different laser wavelengths (red to NIR region). The obtained results show that the cancer cells mixed with AuNPs produce a higher fluorescence peak at 489.2 nm than the cancer cells without AuNPs. Moreover, the optical diffuse reflectance analyses reveal that the addition of AuNPs enhances cancer detection especially at the 635-nm irradiation with sensitivity (94%), specificity (87%), and overall accuracy (91%).

Development of a System to Measure the Optical Properties of Facial Skin using a 3D Camera and Projector

We have developed a system to measure both the optical properties of facial skin and the three-dimensional shape of the face. To measure the three-dimensional facial shape, our system uses a light-field camera to provide a focused image and a depth image simultaneously. The light source uses a projector that produces a high-frequency binary illumination pattern to separate the subsurface scattering and surface reflections from the facial skin. Using a dichromatic reflection model, the surface reflection image of the skin can be separated further into a specular reflection component and a diffuse reflection component. Verification using physically controlled objects showed that the separation of the optical properties by the system correlated with the subsurface scattering, specular reflection, or diffuse reflection characteristics of each object. The method presented here opens new possibilities in cosmetology and skin pharmacology for measurement of the skin's gloss and absorption kinetics and the pharmacodynamics of various external agents.

Temperature dependent luminescence of Pr3+ doped NaCaPO4

Ortho-phosphates according to the composition ABPO4 (A = Li+, Na+, and K+; B = Mg2+, Ca2+, Sr2+, and Ba2+) are often investigated and used as hosts for Pr3+ activated phosphors or scintillators. In this work, the characterisation as well as the synthesis of microcrystalline Na1+xCa1-2xPO4:Pr3+x is discussed. In order to ensure that the investigated samples are single phase compounds, X-ray powder diffraction measurements were performed. The material was studied regarding its suitability as a UV-C emitting phosphor. Furthermore, the emission spectrum in the visible range was evaluated. Spectroscopic examinations included the temperature-dependent determination of the excitation and emission spectra as well as the measurement of the diffuse reflection characteristics. In order to evaluate its suitability as scintillator material, the emission of the samples was measured upon X-ray irradiation.

Comparative analysis of the methods for quantitative determination of water content in skin from diffuse reflectance spectroscopy data

The predictive properties of methods aimed for estimating the water content in skin from the spectral diffuse reflection characteristics near the water absorption line in the near-IR spectral range are analysed. Numerical simulation data, experimental data on diffuse reflection from human skin phantoms, and data from the reference data set of human skin reflectance spectra are used to consider the possibility of gaining additional information about the water distribution in skin. The influence of variations in the scattering coefficient and oxyhaemoglobin concentration on the water content estimates is investigated.

Study on the prediction of soil heavy metal elements content based on visible near-infrared spectroscopy

The estimation of soils heavy metal content can reflect the impending surroundings of surface, which lays theoretical foundation for using covered vegetation to monitor environment and investigate resource. In this study, the contents of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb in 44 soil samples were collected from Fufeng County, Yangling County and Wugong County, Shaanxi Province and were used as data sources. ASD FieldSpec HR (350–2500nm), and then the NOR, MSC and SNV of the reflectance were pretreated, the first deviation, second deviation and reflectance reciprocal logarithmic transformation were carried out. The optimal spectroscopy estimation model of nine heavy metal elements of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb was established by regression method. Comparing the diffuse reflectance characteristics of different heavy metal contents and the effect of different pretreatment methods on the establishment of soil heavy metal spectral inversion model. The results of chemical analysis show that there was a serious Hg pollution in the study area, and the Cd content was close to the critical value. The results show that: (1) NOR, MSC and SNV were adopted for the acquisition of visible near-infrared. Combining differential transformation can improve the information of heavy metal elements in the soil, and use the correlation band energy Significantly improve the stability and predictability of the model. (2) The modeling accuracy of the optimal model of nine heavy metal spectra of Cr, Mn, Ni, Cu, Zn, As, Cd, Hg and Pb by PLSR method were 0.70, 0.79, 0.69, 0.81, 0.86, 0.58, 0.55, 0.99, 0.62. (3) The optimal estimation model of different elements using different treatment methods has better stability and higher precision, and can realize the rapid prediction of nine kinds of heavy metal elements in this region.

Exploring structural colour in uni- and multi-coloured butterfly wings and Ag+ uptake by scales

We discuss the origin of the structural colour of different butterfly wings in the light of the typical built-in microstructural arrangement of scales that are comprised of chitin-melanin layer and air-gaps. Three specimens of butterfly wings namely, Papilio Liomedon (black), Catopsilia Pyranthe (light green) and Vanessa Cardui (multi-coloured) were chosen and diffuse reflectance characteristics have been aquired for normal incidence of p-polarized light. Moreover, the time-dependent uptake of Ag+ into scales has led to swelling and spread of the chitinous ridges and ribs, with revelation of micro-beads in Catopsilia Pyranthe specimen. The reduction of the number of air-gaps between any two parallel ridges is attributed to the merging of adjacent gaps possessing a common boundary. The availability of Ag at the centre of a chosen ridge, for every wing type, follows an exponential growing trend, . Precise inclusion of nanoscale metals into natural photonic systems would provide new insight, while applying principles of photonics and plasmonics simultaneously.

Infrared deflectometry for the inspection of diffusely specular surfaces

Abstract Deflectometry is a full-field gradient technique that lends itself very well to testing specular surfaces. It uses the geometry of specular reflection to determine the gradient of the surface under inspection. In consequence, a necessary precondition to apply deflectometry is the presence of at least partially specular reflection. Surfaces with larger roughness have increasingly diffuse reflection characteristics, making them inaccessible to usual deflectometry. However, many industrially relevant surfaces exist that change their reflection characteristic during production and processing. An example is metal sheets that are used as car body parts. Whereas the molded but otherwise raw metal sheets show a mostly diffuse reflection without sufficient specular reflection, the final car body panels have a high specular reflectance due to the lacquering. In consequence, it would be advantageous to apply the same inspection approach both for the raw material and for the final product. To solve this challenge, specular reflection from rough surfaces can be achieved using light with a larger wavelength, as the specular reflectivity of a surface depends on the ratio of the surface roughness and the wavelength of the light applied. Wavelengths in the thermal infrared range create enough specular reflection to apply deflectometry on many visually rough metal surfaces. This contribution presents the principles of thermal deflectometry, its special challenges, and illustrates its use with examples from the inspection of industrially produced surfaces.

Applications of Ceramic Materials in High Energy Laser Damage

With the consistent improvement of the laser power and energy, further enhancement of the laser resistant ability of the target board is becoming a more and more crucial task in high energy laser diagnostics and irradiation effect studies. Applications of ceramic materials in high energy laser damage were studied. An aluminum panel was coated with ZrO2 ceramic for high power laser proof. Reflectivity and diffuse reflection characteristics of the coating were investigated at different wavelengths. Numerical simulation was conducted to analyze the thermal response of the coating under high power laser radiation. And, related experiments were carried out with high power fiber lasers. Irradiation experiments indicate that the ceramic layer helps to delay the heat conduction and reduce the peak temperature of the target board.

Yb-doped ZnSe nanoparticles: synthesis, physical properties and photocatalytic activity.

In this study, Yb-doped ZnSe nanoparticles were synthesized by co-reduction method at 150 degrees C and pH = 12 for 24 h. The obtained materials were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Powder XRD patterns indicated that the Yb(x)Zn(1-x)Se crystals (x = 0.00-0.10) are isostructural with ZnSe. SEM and TEM images confirmed doping of Yb3+ into the lattice of ZnSe nanoparticles. The UV-Vis diffuse reflectance characteristics of the Yb-doped ZnSe samples were quite similar to that of the undoped sample and showed a strong photoabsorption at visible light range. The electrical conductivity of Yb-doped ZnSe nanomaterials was higher than pure ZnSe at room temperature, and increased with temperature. The photocatalytic activity of synthesized nanoparticles was investigated by the degradation of Orange II solution under visible light irradiation. It was observed that the color removal efficiency of Yb-doped ZnSe catalyst was much higher than that of pure ZnSe (26.28 and 77.10% after 120 min of treatment for ZnSe and Yb(0.06)Zn(0.94)Se, respectively). The results demonstrated the good photocatalytic ability of synthesized nanoparticles under visible light. Also, it was revealed that the decolorization efficiency of Orange II over Yb-doped ZnSe increased with increasing Yb loading up to 6 mol% and then decreased.

Enhancement of the photocatalytic performance of Ni-loaded TiO2 photocatalyst under sunlight

A highly sunlight active Ni-loaded TiO2 nanocomposite (Ni/TiO2) is successfully prepared by a simple chemical reduction method using tetrabutyl titanate as a precursor, Ni(NO3)2·6H2O as a nickel source, and N2H4·H2O as a reductant, respectively. The crystal structure, morphology and UV–vis diffuse reflectance characteristics are investigated by XRD, TEM, and UV–vis diffuse reflectance spectroscopy, while the photocatalytic performance of Ni/TiO2 is evaluated by photocatalytic degradation of methyl orange solution under UV and sunlight irradiation. Results show that the crystal structure of TiO2 is not changed upon the loading of Ni, the photocatalytic performance of TiO2 under both UV-light and sunlight, however, is enhanced greatly. The enhancement of the photocatalytic performance of Ni/TiO2 is attributed to the increase of the photogenerated electron–hole separation efficiency and the advanced absorption of light due to surface plasmon effect of Ni nanoparticles.

Special Light Illumination Detection Dethod Based on Integrating Sphere Technology

This paper studies the measurement of illumination parameters from a bright product. We are making use of diffuse reflection characteristics of the integrating sphere, which can greatly reduce the measurement error caused by the shape of the light, the divergence angle, and different location on the detector. In this way we can measure the intensity of the light source accurately, and the measurement accuracy less than 5%.

The effect on sound propagation in streets of the distribution of acoustic scatterers on facades

Until recently street noise propagation models assumed that faade reflections were either totally specular or totally diffuse. However, the characteristics of building facades are such that some energy will be reflected specularly and some diffusely. Many current models, therefore, use a scattering coefficient to characterize the diffuse reflection characteristics and the assumption is made that a fraction of the sound energy falling on any point on the facade will be scattered to the same degree. From observation it can be seen that facades are not homogeneous but consist of surfaces which are planar in nature but feature discontinuities such as windows, doors, ledges, etc. which will tend to act as distributed scattering centers. The effect of distributions of scattering centers on the propagation of sound in streets is examined using a combined image source and randomly scattered sound rays. Computer generation of street models using an object based approach enables the study of many different configurations using RAYNOISE software. Results are compared with those obtained assuming a homogeneous distribution of facade scattering using both RAYNOISE and a technique proposed by the authors. The results of a scale model experiment to investigate the effect of distributed scatters are presented.

Dissolution and diffuse reflectance characteristics of coated theophylline particles

The aim of the present study was to investigate how the dissolution and diffuse reflectance characteristics of theophylline microcapsules were influenced by the changes in the thickness and by the plasticizer content of coating. Microencapsulation was carried out in laboratory fluidized-bed system using water dispersable Eudragit-type film coating polymer. United States Pharmacopeia rotating paddle method was applied for the in vitro dissolution study. The dissolution profile of the produced microcapsules was evaluated by Weibull distribution. The effect of the thickness of coating and that of the plasticizer content on the dissolution kinetics was modelled by a second-order polynomial equation fitted to the data gathered by a face-centered central composite statistical design. It was found that both of the examined coating parameters influenced the drug release kinetics. The diffuse reflectance spectra of the coated particles indicated the changes in coating parameters without destructive analysis of samples.

Radiative transport in a planar medium exposed to azimuthally unsymmetric incident radiation

An analytical solution is developed for the radiation field engendered by illuminating an absorbing/anisotropically scattering planar medium with an azimuthally unsymmetric incident flux. The boundaries of the medium are allowed to possess both specular and diffuse reflection characteristics. The problem is mathematically reduced to solving a system of azimuthally independent equations which may be analyzed by many existing techniques. A solution scheme is formulated in terms of singular eigenfunctions and solved using a modified F N method. Computations are performed for the azimuthally symmetric case of irradiation by parallel rays at oblique incidence. Several different phase functions are considered and results are presented for the discrete eigenvalues, the heat flux distributions within the medium, the reflectance and transmittance of the slab and the angular distribution of the intensities at the boundaries.

FACTORS AFFECTING COLOR AND APPEARANCE OF CORN TORTILLAS

ABSTRACT.A study is described which examined the relative contributions of production and post‐production variables on color and appearance of corn tortillas. Tortillas processed at three production sites were stored under exact marketing conditions in refrigerated display cases in three supermarkets. Reflectance measurements and visual evaluations immediately on delivery showed that processing variables contributed heavily to initial appearance and color differences. Rate of appearance deterioration on storage was affected by both processing and storage variables. The rate and magnitude of visually perceived changes on storage was not paralleled by a similar rate and magnitude of change in diffuse reflectance characteristics. This suggests that the visually perceived changes were due to structural rather than color changes.