Download or read book Apparatus and Method for Qualitative and Quantitative Measurements of Optical Properties of Turbid Media Using Frequency domain Photon Migration written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical measurements of turbid media, that is media characterized by multiple light scattering, is provided through an apparatus and method for exposing a sample to a modulated laser beam. The light beam is modulated at a fundamental frequency and at a plurality of integer harmonics thereof. Modulated light is returned from the sample and preferentially detected at cross frequencies at frequencies slightly higher than the fundamental frequency and at integer harmonics of the same. The received radiance at the beat or cross frequencies is compared against a reference signal to provide a measure of the phase lag of the radiance and modulation ratio relative to a reference beam. The phase and modulation amplitude are then provided as a frequency spectrum by an array processor to which a computer applies a complete curve fit in the case of highly scattering samples or a linear curve fit below a predetermined frequency in the case of highly absorptive samples. The curve fit in any case is determined by the absorption and scattering coefficients together with a concentration of the active substance in the sample. Therefore, the curve fitting to the frequency spectrum can be used both for qualitative and quantitative analysis of substances in the sample even though the sample is highly turbid.
Download or read book Official Gazette of the United States Patent and Trademark Office written by and published by . This book was released on 1995 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantitative Broadband Absorption and Scattering Spectroscopy in Turbid Media by Combined Frequency domain and Steady State Methodologies written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique for measuring broadband near-infrared absorption spectra of turbid media that uses a combination of frequency-domain and steady-state reflectance methods. Most of the wavelength coverage is provided by a white-light steady-state measurement, whereas the frequency-domain data are acquired at a few selected wavelengths. Coefficients of absorption and reduced scattering derived from the frequency-domain data are used to calibrate the intensity of the steady-state measurements and to determine the reduced scattering coefficient at all wavelengths in the spectral window of interest. The absorption coefficient spectrum is determined by comparing the steady-state reflectance values with the predictions of diffusion theory, wavelength by wavelength. Absorption spectra of a turbid phantom and of human breast tissue in vivo, derived with the combined frequency-domain and steady-state technique, agree well with expected reference values.
Download or read book Frequency Domain Photon Migration Measurements written by Sharnay Etasha Torrance and published by . This book was released on 2004 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement and Analysis of Optical Properties of Turbid Media written by Ilpo Niskanen and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Literaturangaben.
Download or read book Method and Apparatus for Measuring the Intensity and Phase of One Or More Ultrashort Light Pulses and for Measuring Optical Properties of Materials written by and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The intensity and phase of one or more ultrashort light pulses are obtained using a non-linear optical medium. Information derived from the light pulses is also used to measure optical properties of materials. Various retrieval techniques are employed. Both "instantaneously" and "non-instantaneously" responding optical mediums may be used.
Download or read book Characterization of Two Layer Diffuse Media by Reflection of Gigahertz Photon Density Waves written by and published by . This book was released on 2001 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffuse reflected light is used to characterize optical properties of two-layer turbid media. The source is modulated in gigahertz frequencies. The phase and amplitude of analytical reflectance is fitted to the data generated by adding 2.5% noise in amplitude and 1 degree noise in phase to the solution of diffusion approximation in gigahertz frequency regime. The extracted optical properties are in good agreement with the real values.
Download or read book Optical Imaging Through Turbid Media with a Degenerate Four wave Mixing Correlation Time Gate written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical imaging through turbid media is demonstrated using a degenerate four-wave mixing correlation time gate. An apparatus and method for detecting ballistic and/or snake light while rejecting unwanted diffusive light for imaging structures within highly scattering media are described. Degenerate four-wave mixing (DFWM) of a doubled YAG laser in rhodamine 590 is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore has lost memory of the structures within the scattering medium. Images have been obtained of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye, which demonstrates the utility of DFWM for imaging through turbid media. Use of DFWM as an ultrafast time gate for the detection of ballistic and/or snake light in optical mammography is discussed.
Download or read book Development of a New Spectrophotometric Method for Full Characterization of Turbidity written by Stephen M Mutisya and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Characterization of turbid materials by determining their inherent optical properties have attracted strong research interest for potentially wide applications in fields such as material analysis and biomedical optics. The response of a homogeneous turbid sample to an optical excitation can be accurately described by absorption coefficient [mu]a, scattering coefficient [mu]s, and anisotropy factor g based on the radiative transfer theory. Existing spectrophotometric methods typically uses integrating spheres to acquire the light signals. These approaches, however, are difficult to be translated into instruments for users without special training. The research goal of this dissertation research project is two-fold: (1) Develop and validate a new spectrophotometric method without integrating sphere to characterize turbidity for optically thick samples by three optical parameters of [mu]a([lambda]), [mu]s([lambda]) and g([lambda]). (2) Demonstrate the applicability of the new spectrophotometric method as a label-free assay of cell suspension samples treated by a chemotherapy drug. An experimental system has been developed to measure signals of diffuse reflectance Rd, diffuse transmittance Td and forward transmittance Tf as functions of wavelength [lambda] between 460 and 1000nm from two types of samples. We have inversely determined the optical parameters of polystyrene microsphere samples by an in-house build individual photon Monte Carlo (iMC) simulation software. Validation of the new method has been achieved by comparing the optical parameters determined from the measured signals to those predicted by the Mie theory. In addition, we have applied the validated method to obtain the optical properties of MCF-7 cell samples treated by an apoptosis inducing drug doxorubicin for three different doses and three post-treatment times. By comparing to apoptosis measurement results of MTT assay and fluorescent flow cytometry, we were able to qualitatively demonstrate the potential applications of the new spectrophotometric method as a label-free assay to detect cellular apoptosis in treated samples.
Download or read book Optical Spectroscopy of Turbid Media written by Erik Alerstam and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Time correlated single photon counting written by Desmond O'Connor and published by Academic Press. This book was released on 2012-12-02 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-correlated Single Photon Counting has been written in the hope that by relating the authors' experiences with a variety of different single photon counting systems, they may provide a useful service to users and potential users of this formidably sensitive technique. Of all the techniques available to obtain information on the rates of depopulation of excited electronic singlet states of molecular species, monitoring of fluorescence provides, in principle, the simplest and most direct measure of concentration. This volume comprises eight chapters, with the first focusing on the time dependence and applications of fluorescence. Succeeding chapters go on to discuss basic principles of the single photon counting lifetime measurement; light sources; photomultipliers; electronics; data analysis; nanosecond time-resolved emission spectroscopy; time dependence of fluorescence anisotropy. This book will be of interest to practitioners in the field of chemistry.
Download or read book SOME OPTICAL PROPERTIES OF TURBID MEDIA written by and published by . This book was released on 1964 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical Properties of Absorbing and Turbid Liquids written by Anssi Jääskeläinen and published by . This book was released on 2001 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytic Transfer Function of the Forward Propagation of Diffuse Photon Density Waves in Turbid Media with an Embedded Spherical Inhomogeneity written by Deborah L. Lasocki and published by . This book was released on 1997-12-01 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusing photons can be used to detect and localize optical inhomogeneities embedded in turbid media such as clouds, fog, paint and human tissue. This thesis shows that a transfer function derived from an analytic solution of the Helmholtz equation can completely characterize in three dimensions the perturbations in the forward propagation phenomena caused by a spherical defect object in a multiple-scattering medium. Two models of the forward propagation behavior of diffuse photon density waves in homogeneous, infinite, turbid media that contains a spherical inhomogeneity are examined. The first model is an exact analytic solution based on a modal expansion in spherical harmonics. The second model uses Fourier optics theory for wave propagation in a plane through homogeneous turbid media containing a spherical lens. The Fourier optics model is found to be a good approximation to the exact analytic solution when the optical absorptive contrast of the inhomogeneity and the surrounding media is weakly perturbative, and the detector is not near the inhomogeneity. Using linear system theory, a transfer function from the analytic model is derived. This function improves the Fourier optics model by replacing the spherical lens approximation with an exact representation of the system perturbation behavior. The transfer function is shown through simulation to completely characterize the sensitivity of the system to detect and localize in three dimensions inhomogeneities of varying optical contrast with the surrounding media.
Download or read book Apparatus for in Situ Measurements of Optical Properties of Evaporated Thin Films written by N. BLUZER and published by . This book was released on 1973 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: A SINGLE BEAM DEVICE WHICH MEASURES CONTINUOUSLY AS A FUNCTION OF WAVELENGTH REFLECTANCE AND TRANSMITTANCE IS DESCRIBED. THE UNIT IS ATTCHED TO A MCPHERSON 218 MONOCHROMATOR, BUT IT CAN BE ADAPTED FOR ANY MONOCHROMATOR. A NOTABLE FEATURE OF THE DEVICE IS THAT WITH A SPECIALLY CONSTRUCTED VACUUM EVAPORATOR THIS SYSTEM ENABLES THE STUDY OF THE OPTICAL PROPERTIES OF THIN FILMS WITHOUT EXPOSING THEM TO AIR. DESCRIBED ALSO IS A FEEDBACK LIGHT CONTROL SYSTEM DESIGNED TO COMPENSATE FOR SIGNAL INTENSITY VARIATIONS WITH WAVELENGTH CAUSED BY VARIOUS OPTICAL COMPONENTS.
Download or read book Real time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms written by Babin, Marcel and published by UNESCO. This book was released on 2008-06-05 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.
Download or read book Holographic Sensors written by Ali Kemal Yetisen and published by Springer. This book was released on 2014-12-03 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a theoretical and experimental approach for the rapid fabrication, optimization and testing of holographic sensors for the quantification of pH, organic solvents, metal cations, and glucose in solutions. Developing non-invasive and reusable diagnostics sensors that can be easily manufactured will support the monitoring of high-risk individuals in any clinical or point-of-care setting. Sensor fabrication approaches outlined include silver-halide chemistry, laser ablation and photopolymerization. The sensors employ off-axis Bragg diffraction gratings of ordered silver nanoparticles and localized refractive index changes in poly (2-hydroxyethyl methacrylate) and polyacrylamide films. The sensors exhibited reversible Bragg peak shifts, and diffracted the spectrum of narrow-band light over the wavelength range λpeak ≈ 495-1100 nm. Clinical trials of glucose sensors in the urine samples of diabetic patients demonstrated that they offer superior performance compared to commercial high-throughput urinalysis devices. Lastly, a generic smartphone application to quantify colorimetric tests was developed and tested for both Android and iOS operating systems. The sensing platform and smartphone application may have implications for the development of low-cost, reusable and equipment-free point-of-care diagnostic devices.
