Application Of Optical Techniques Research Articles

Application of optical techniques in sedimentation study of magnetorheological fluids

Application of optical techniques in sedimentation study of magnetorheological fluids

Special Issue “Neurophotonics—Optics for the Brain”

Light-tissue interactions allow for a multitude of possibilities to sense; image; and impact the brain at molecular, cellular, and tissue levels. The application of optical techniques to neuronal tissue is the essence of neurophotonics, to which this Special Issue is dedicated. The eleven articles in this Special Issue are representative of the broad scope of this field and of the wide range of optical techniques that it encompasses. In more detail, the articles cover basic neuroscience, neuroanatomy, functional imaging, cerebral hemodynamics, brain development and aging, brain–computer interfaces, and therapeutic treatments. The optical techniques considered include various types of optical microscopy, optical coherence tomography, photoacoustic imaging, diffuse optical spectroscopy and imaging, photobiomodulation, and optogenetics.

Optical Identification of Plasmodium falciparum Malarial Byproduct for Parasite Density Estimation

Plasmodium falciparum (P. falciparum) malarial degree of infection, termed as parasite density (PD), estimation is vital for point-of-care diagnosis and treatment of the disease. In this work, we present application of optical techniques: optical absorption and multispectral imaging for P. falciparum malarial byproduct (hemozoin) detection in human‐infected blood samples to estimate PD. The blood samples were collected from volunteers who were tested positive for P. falciparum infections (i-blood), and after treatment, another set of blood samples (u-blood) were also taken. The i-blood samples were grouped based on PD (+, ++, +++, and ++++). Optical densities (ODs) of u-blood samples and i-blood samples at blood absorption bands of 405 nm, 541 nm, and 577 nm showed different optical absorption characteristics. Empirical computation of ratio of the ODs for the blood absorption bands revealed reduction in the ODs with increasing PD. Multispectral images containing uninfected red blood cells (u-RBCs) and P. falciparum‐infected red blood cells (i-RBCs) on unstained blood smear slides exhibited spectrally determined decrease in both reflected and scattered pixel intensities and increase in transmitted pixel intensities with increasing PD. We further propose a linear classification model based on Fisher’s approach using reflected, scattered, and transmitted pixel intensities for easy and inexpensive estimation of PD as an alternative to manual estimation of PD, currently, the widely used technique. Application of the optical techniques and the proposed linear classification model are therefore recommended for improved malaria diagnosis and therapy.

Complex deformation of naturally fractured rocks

Strain is a key parameter in the evaluation of rock mechanical properties and failure behavior. Strain is usually measured using strain gauges, however, this laboratory method has inherent uncertainty in the attachment of sensitive gauges to the rock surface and it is limited to one-point strain measurement. In complex geometries such as rock samples with natural fractures or lamination, that classical approach cannot provide the whole picture of strain development in such complex geometries. To overcome these challenges, the application of optical technique with image processing is proposed. The optical technique has the advantage of being a non-contact method and it provides quantitative visualization of full-field strain measurement.To examine quantitative visualization of strain development, DIC technique was first conducted on a homogeneous sandstone sample as a benchmark. The results verify that the maximum tensile strain is developed at the central vertical line of the sample as it was expected from theoretical solutions. This DIC measurement matches the post-failure fracture pattern of the specimen. Then the technique was applied on the Buda Limestone samples with horizontal, sub-horizontal or multiple complex natural fractures (sealed or partially open) and inclusions while the samples were under diametrical compression experiment. The results of this study provide further insight into the role of natural fractures on induced fracture initiation and propagation under this specific testing condition. Horizontal natural fractures are planes of maximum compressive strain which can delay the propagation of vertical tensile fractures. The maximum amount of tensile strain usually initiates at the boundary of these natural fractures and vertical tensile fractures usually deviate toward horizontal fracture for a short distance before turning back to propagate vertically following the maximum stress path. Full-field surface deformations are mapped optically in the crack–inclusion vicinity where DIC results showed that crack front is arrested by the inclusion for the complete fracture event. In contrast to the failure pattern in homogenous sandstone specimen, complex fracture pattern was observed on several specimens with multiple fracture network. Fracture slippages along the natural fracture, fracture deviation was observed in samples with steep inclined natural fractures.The results of this study can help us to better understand the complex failure mechanism in naturally fractured media and elaborate on various mechanisms of failure under diametrical compression tests. DIC is a powerful technique in providing the dynamic strain development over the surface of the sample in real-time, thus it can provide the fracture initiation and propagation in such heterogeneous rock media.

Classification of Wine Grape Based on Different Phytosanitary Status by Using Visible/Near Infrared Spectroscopy

The grape selection at the consignment is crucial for big cooperative companies with thousands of members, and therefore grapes may have different quality characteristics and health status. The quantification of diseases on wine grapes is commonly performed by a visual evaluation of the infection symptoms in grape bunches. Based on grapes quality, wineries often enforce a price penalty downgrading the grapes value imposing a severe reduction of vine growers’ income. The application of optical techniques could minimize contentious between members and winery and could improve the standardization of the grape quality and therefore of the wine. The aim of this work was to investigate the applicability of vis/NIR spectroscopy for a rapid assessment of phytosanitary status of grape bunches directly at the check point at the grape consignment. This preliminary experimental step was conducted in lab-scale condition using a vis/NIR device built specially for analysis of non-homogeneous product in the spectral range 400-1650 nm. Spectral measurements were carried out on healthy (1235 samples) and diseased bunches (1324) from white and red grapes for a total of 2559 spectra. Quantitative (Partial Least Squares – Discriminant Analysis, PLS-DA) analyses were applied on grape spectra in order to test the performance of vis/NIR spectroscopy to classify healthy and infected bunches. The results obtained from PLS-DA models, in cross-validation, gave positive predictive values of classification between 89.8 % and 91.1 %. Results demonstrated that vis/NIR spectroscopy is capable to provide useful information about wine grape phytosanitary status. However, further studies and real scale measurements are needed to determine the best operating conditions for a future engineering phases to perform the measurements directly at the consignment check point station.

Multimodal optical setup based on spectrometer and cameras combination for biological tissue characterization with spatially modulated illumination.

The application of optical techniques as tools for biomedical research has generated substantial interest for the ability of such methodologies to simultaneously measure biochemical and morphological parameters of tissue. Ongoing optimization of optical techniques may introduce such tools as alternative or complementary to conventional methodologies. The common approach shared by current optical techniques lies in the independent acquisition of tissue’s optical properties (i.e., absorption and reduced scattering coefficients) from reflected or transmitted light. Such optical parameters, in turn, provide detailed information regarding both the concentrations of clinically relevant chromophores and macroscopic structural variations in tissue. We couple a noncontact optical setup with a simple analysis algorithm to obtain absorption and scattering coefficients of biological samples under test. Technically, a portable picoprojector projects serial sinusoidal patterns at low and high spatial frequencies, while a spectrometer and two independent CCD cameras simultaneously acquire the reflected diffuse light through a single spectrometer and two separate CCD cameras having different bandpass filters at nonisosbestic and isosbestic wavelengths in front of each. This configuration fills the gaps in each other’s capabilities for acquiring optical properties of tissue at high spectral and spatial resolution. Experiments were performed on both tissue-mimicking phantoms as well as hands of healthy human volunteers to quantify their optical properties as proof of concept for the present technique. In a separate experiment, we derived the optical properties of the hand skin from the measured diffuse reflectance, based on a recently developed camera model. Additionally, oxygen saturation levels of tissue measured by the system were found to agree well with reference values. Taken together, the present results demonstrate the potential of this integrated setup for diagnostic and research applications.

光学技术的创新应用：细菌芽孢萌发机理研究

光学技术的创新应用：细菌芽孢萌发机理研究

Dictionary of biomedical optics and biophotonics—A book review

VALERY Tuchin, a leading expert in biophotonics and biomedical optics, guest editor of the special issue on in vivo flow cytometry (1), coeditor of the Journal of Biophotonics (2), and editor of numerous textbooks recently published a dictionary on biomedical optics and biophotonics (3). Biophotonics can be described as the ‘‘development and application of optical techniques, particularly imaging, to the study of biological molecules, cells and tissue’’. One of the main benefits of using optical techniques which make up biophotonics is that they preserve the integrity of the biological cells being examined, according to Wikipedia (4), with an extensive explanation. So one may critically ask: Is it timely to publish a printed dictionary in the era of Wikipedia? The dictionary with approximately 2500 key terms and 576 pages is bolded throughout the text to direct the reader from definition to definition (similar to a hyperlink) and gives a rich understanding of the terminology in this quickly developing field. The key terms were selected by Professor Tuchin from the glossaries of his numerous text books on this topic and all definitions are precise and to the point. It contains all terms relevant for those working with biological material in combination with high-end optical technologies and is thereby a unique publication in the field. Even so, why have a 700g book on your shelf when all the information is also available on the web, in addition to rich information density, graphical explanations, and so on? But is the web information really better? I made, as an experimental scientist, the test. I selected arbitrary key words from the dictionary and looked them up in Wikipedia. And the answer is yes, you can also find the terms on the web but most explanations are extensive whereas those in the dictionary are crisply short and topically focused on biophotonics’ relationship. Not only that, but looking the terms up in the book is (astonishingly) faster than doing it via the internet. Still, for the electronic display aficionados the whole content of the dictionary is also available in electronic format so that you may also search and find key words on your tablet PC. Who should read it? In my view, Valery Tuchin’s dictionary is a must-have reference for all novices in the field. It is a rapid way to find definitions and connections with other fields and should be on the optical bench in any biophotonic laboratory.

Application of optical techniques for in situ analysis of plasma facing carbon tiles

Optical absorption/emission spectroscopy is considered to be used for in situ characterization of plasma facing carbon tiles and quantitative evaluation of tritium. In this paper we have applied ex situ laser Raman spectroscopy for carbon tiles used as first wall and divertor in JT-60 exposed to HH discharge plasma to verify the applicability of the technique. The analysis shows that the micro-structure of the carbon tile surfaces is modified in a similar way like damaging by energetic ion irradiation and that one can get information of how graphite structures are damaged by plasma exposure or what kind of structures the redeposited carbon obtains.

Applications of Digital Correlation Method to Structure Inspection

In structure inspections, applications of optical techniques are rare, but the advantages of a non-contact, full field technique using a simple apparatus are attractive. The main requirements for structure inspection are the full-field strain measurement with the required precision and on-site measurement ability. The digital correlation method (DCM), a new optical deformation measurement tool, can satisfy all of the requirements for structure inspection. A smoothing algorithm which can greatly improve the strain measurement precision, and a 3-D DCM have been developed in this paper. For verifying this improvement, a comparison of strain measurements by computer-simulated speckle images has been carried out. Additionally, three structure inspection examples that cover typical materials and structure styles are presented: the interface shear stress distribution for reinforced concrete piles bedded on rock, the 3-D strain distribution of a composite vessel structure, and stresses in a hookup that connects two steel bridge structures. All the examples show that the new structural inspection tool is exemplary and illustrates the obvious advantages of this optical non-destructive technique.

Time resolved electroluminescence measurements on GaAs and GaN devices

Time correlated single photon electroluminescence maps have been recorded on operating semiconductor devices with a spatial resolution approaching 1μm and a time resolution of 50 ps. The technique is noninvasive and observes signal wave forms optically, directly at the device. Spectral measurements in the near infrared and visible were also performed. Two examples of the application of this technique to semiconductor devices are presented. An AlGaAs∕GaAs heterojunction bipolar transistor typical of high speed bipolar devices used in rf circuitry, and an AlGaN∕GaN heterostructure field-effect transistor as an example of the application of optical techniques in characterizing the emerging technology.

New photonic technologies for the treatment and diagnosis of hepatic diseases: an overview of the experimental work performed in collaboration, between Physics Institute of São Carlos and Ribeirão Preto Faculty of Medicine of the University of São Paulo

Recent advances in optical techniques have created a great range of possibilities for diagnosis and therapeutics in liver related diseases. With the uses of efficient light sources like lasers and LEDs (Light Emitting Diodes) it is possible to employ the light-tissue interaction to promote hepatic tissue regeneration after partial hepatectomy, to detect hepatocarcinoma and steatosis by utilizing optical fluorescence, to evaluate the metabolism of the liver during hepatic transplantation as well as to treat liver tumors. We present here an overview of the technique presently in development at the Ribeirâo Preto Faculty of Medicine-USP in cooperation with the Physics Institute of São Carlos-USP. The results obtained so far have been the subject of a list of publications and are here presented as an overview. A new perspective for modern application of optical techniques in different medical practices related to the liver is presented.

Industrial applications of optical techniques that measure displacements

Full-field optical techniques have reached a level of development that makes them ideal tools to solve many practical industrial problems. The areas of application include metrology; nondestructive evaluation of components; solutions to stress analysis problems, both static and dynamic; and development of sensors. In metrology, of particular significance are problems of three-dimensional (3-D) shape measurement. The shape measurement is connected to computer-aided design/computer-aided manufacturing programs, rapid prototyping, and reverse engineering. Unlike tactile machines that provide single-point data, optical methods provide high-density information, and their accuracy has reached a level comparable to tactile machines. This information makes feasible a number of new applications of high industrial interest in reverse engineering. Another area of great interest is 3-D visualization. Other areas of growth are the detection of flaws in nondestructive evaluation, problems arising from dynamic effects, refining of modeling techniques, and development of new sensors. A completely new area of application is the use of optical techniques in the field of microelectromechanical systems and in the area of nanosciences. Very recent work shows that one can go beyond the Rayleigh limit and obtain information at the nanolevel. It is possible to anticipate that a great expansion will take place in these fields in the next few years.

Optical characterization techniques for process monitoring

AbstractThe aim of this special issue is to bring to the attention of the surface science community the potential and application of optical techniques. This paper gives an overview of the major optical characterization techniques and the subsequent papers. Where possible, links with other surface science techniques are discussed and the use of optical methods for process monitoring and control is emphasized. © Crown Copyright 2001. Published by John Wiley & Sons, Ltd.

Optical characterization techniques for process monitoring

The aim of this special issue is to bring to the attention of the surface science community the potential and application of optical techniques. This paper gives an overview of the major optical characterization techniques and the subsequent papers. Where possible, links with other surface science techniques are discussed and the use of optical methods for process monitoring and control is emphasized. © Crown Copyright 2001. Published by John Wiley & Sons, Ltd.

Applied Optical Measurements: Heat and Mass Transfer

This book, dedicated to Professor�Franz Mayinger, contains a large selection of recent work on the application of optical techniques to heat and mass transfer. The book is arranged in the form of a selection of technical papers sourced from high profile international workers in the field, including Durst, Goldstein and Whitelaw, to name a few. The book is split into three sections looking at general technique application, multiphase flow and combustion application of various optical techniques. Major techniques reviewed include liquid crystal approaches, holographic methods, laser and phase Doppler techniques and tomographic methods. There are also additional articles on areas such as heat exchanger design and porous medium combustion technology. The technical level of the book is high, and a good background knowledge in optical methods is assumed by the authors. It is therefore not suitable as an introductory text in the subject area, but is thoroughly recommended as a comprehensive reference for postgraduate or industrial researchers who are closely involved in optical techniques for fluid mechanics. Nick Lawson

Highly accurate non-contact characterization of engineering surfaces using confocal microscopy

Optical non-contact techniques are very interesting for 3D characterization of sensitive and complex engineering surfaces. Unfortunately, the application of optical techniques was for many years restricted to selected types of surfaces which have only moderate variations of height and surface slope relative to their lateral resolution and measurement field. Owing to the fact that artefacts and form deviations occur with high spatial frequencies in optically measured topographs, there were some difficulties in interpreting the results and comparing them with the tactile standard techniques for surface characterization. Furthermore, artefacts in optically measured profiles have often been misinterpreted in terms of the resolution of optical techniques being higher than that of the tactile techniques. This paper presents two optical methods of confocal microscopy for highly accurate characterization of surfaces. The first method works on measurement fields of less than 1 and is in practice absolutely comparable to the mechanical stylus instrument, even on rough surfaces. For this method results compare very well not only in surface statistics but also in topographic raw data, as will be demonstrated for the PTB roughness standards. The second method works on measurement fields up to square centimetres.

Rate-equation model for quantitative concentration measurements in flames with picosecond pump–probe absorption spectroscopy

Measurement of radical concentrations is important in understanding the chemical kinetics involved in combustion. Application of optical techniques allows for the nonintrusive determination of specific radical concentrations. One of the most challenging problems for investigators is to obtain flame data that are independent of the collisional environment. We seek to obviate this difficulty by the use of picosecond pump-probe absorption spectroscopy. A picosecond pump-probe absorption model is developed by rate-equation analysis. Implications are discussed for a laser-pulse width that is much smaller than the excited-state lifetime of the absorbing atom or molecule. The possibility of quantitative, quenching-independent concentration measurements is discussed, and detection limits for atomic sodium and the hydroxyl radical are estimated. For a three-level absorber-emitter, the model leads to a novel pump-probe strategy, called dual-beam asynchronous optical sampling, that can be used to obtain both the electronic quenching-rate coefficient and the doublet mixing-rate coefficient during a single measurement. We discuss the successful demonstration of the technique in a companion paper [Appl. Opt. 34, XXX (1995)].

ICA in the UK Water Industry: Highlights of Recent Developments in the Applications of Optical Techniques

The current situation in respect of the impact of recent legislation and funding mechanisms on progress with developments in instrumentation, control and automation (ICA) in the UK Water Industry is discussed, problems with progress identified and potential solutions discussed. Recent developments in applied optical sensing are detailed, particularly those involving the use of Raman Scattering and optical fluorescence utilising non-contact laser probes and detectors and fibre-optic based sensors for use in portable and permanent station monitors.

The application of optical techniques in aspheric surface assessment

During the last decade, there has been a dramatic increase in the number of aspheric optical systems generated. Two large contributors to this are the Compact Disc Lens' focusing system and the Ophthalmic contact lens industry. The requirement for faster and more accurate methods of quality control has increased proportionally. The paper briefly discusses methods of manufacturing such complex forms, measurement methods available and describes a unique system for assessing the absolute form error, forming an open loop feedback system to the manufacturing cell. Reference to the Form Talysurf Laser Interferometric measurement system will be made, with a full description of gauging technology utilised. The implementation of the Michelson Interferometer and necessity for arcuate correction of the stylus tip in a pivoted arm arrangement will be described. The general aspheric form will be discussed which emphasises the need for Form and Surface Texture analysis. The paper then proposes methods of analysis that may be necessary in the future for aspheric and other complex forms.