Papers by Indu FieslerSaxena
Applied optics, Sep 10, 1996
Sigmoid-like activation functions as available in analog hardware di er in various ways from the ... more Sigmoid-like activation functions as available in analog hardware di er in various ways from the standard sigmoidal function as they are usually asymmetric, truncated, and have a non-standard gain. We present an adaptation of the backpropagation learning rule to compensate for these non-standard sigmoids. This method is applied to multilayer neural networks with all-optical forward propagation and liquid crystal light v alves (LCLV) as optical thresholding devices. In this paper, the results of simulations of a backpropagation neural network with ve di erent LCLV response curves as activation functions are presented. While performing poorly with the standard backpropagation algorithm, it is shown that our adapted learning rule performs well with these LCLV curves.
Optical fiber static strain sensors: reliability issues
SPIE Proceedings, 2007
There is much interest in using optical fiber sensors for strain measurement because they are lig... more There is much interest in using optical fiber sensors for strain measurement because they are lightweight and are insensitive to electromagnetic interference. Structural monitoring applications can employ fiber Bragg gratings (FBGs) for point-by-point measurements, whereas continuous sensors, based on Brillouin scattering, can be used to measure strain along entire lengths of un-modified optical fibers. These two strain measurement methodologies, and their practical limitations, are compared. Accurate and reliable static strain measurement with FBGs, a turnkey instrumentation with multichannel detection ability, and embedding techniques with repeatable calibration ability are reported. Embedding techniques that survive high temperature cycling, and high humidity under salt water environments, have been developed.
Bacteria sensor and method
Bacteria sensor and method
Apparatus and Method for High Resolution Temperature Measurement and for Hyperthermia Therapy
An all-optical forward propagation multilayer neural network
Lecture Notes in Computer Science, 1995
ABSTRACT An adaptive multilayer optical neural network with optical thresholding by a liquid crys... more ABSTRACT An adaptive multilayer optical neural network with optical thresholding by a liquid crystal light valve (LCLV) and all-optical forward propagation is described. It has a large number of modifiable optical interconnections which are implemented by liquid crystal television screens, and it has a modular structure allowing the cascading of layers, each layer with its own light source.
Propagation Loss with Frequency of Ultrasound Guided Waves in a Composite Metal-Honeycomb Structure
Proceedings of Spie the International Society For Optical Engineering, 2009
High-speed digital ellipsometer for the study of fiber optic sensor systems
Fiber Optic and Laser Sensors VIII, 1991
ABSTRACT The paper describes a high-speed digital ellipsometer, called 'discrete retardat... more ABSTRACT The paper describes a high-speed digital ellipsometer, called 'discrete retardation modulation ellipsometer', designed for investigating fiber-optic sensor systems. The new device uses an electrooptic modulator to extract all four Stokes parameters and, thus, does not require lock-in amplifiers. The ellipsometer was used to measure the response of an optical fiber current sensor to test current at 4 kHz. The result was found to be within 10 percent from the expected value.
Apparatus and Method for Damage Location and Identification in Structures
Detection of Bacteria Accumulations ( Biofilm) on the Interior Walls of Tubes or Conduits Carrying Fluids in Which Bacteria Are Entrained by Using a Bacterial Target Substrate in the Conduit ; Autofluorescence
Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications VIII, 2008
Radiation doses used in radiation therapy are calculated during the course of treatment planning.... more Radiation doses used in radiation therapy are calculated during the course of treatment planning. Cross-validation of calculated dose versus received dose is performed mostly in-vitro and may not represent actual therapy doses. In vivo measurements are at best typically limited to a few surface points. Presently, dose is measured primarily with diodes, thermoluminescent or MOSFET dosimeters. Their outer sizes are in the range of 3 mm, which are unpractical for in vivo internal use, in particular for interstitial or intracavital brachytherapy. In addition, diode and MOSFET sensors are individually tethered to cables and are therefore inconvenient for making multiple point measurements. Feasibility of multiple point radiation dosimetry using luminescent optical fibers for in vivo dosimetry during radiation therapy is described that overcomes these difficulties. The spectral response of a candidate rare-earth doped optical fiber dosimetric probe is reported, having 0.5 rads/cm sensitivity. This sensor capability would enable continuous radiation monitoring of dose and dose rate during therapy at multiple locations along the sensor fiber.
<title>Characterization of an ADP electro-optic modulator in the near-IR</title>
Electro-Optic and Magneto-Optic Materials II, 1990
ABSTRACT Electro-optic modulators (EOM&#39;s) can be used for polarization modulation of ligh... more ABSTRACT Electro-optic modulators (EOM&#39;s) can be used for polarization modulation of light at frequencies up to hundreds of megahertz and are therefore strong candidates for high speed effipsometer systems. The characteristic of this device is the half wave voltage, V ,which is a function of the wavelength of light and the temperature. A description of the particular ADP EOM we are using, and a discussion of the effect of laser linewidth and temperature on the measurement of V,, is presented. For the laser diode wavelength of )t = 830 nm, V, and the extinction ratio are measured at different temperatures.
Optical Multilayer Perceptrons based on Liquid Crystal Devices
Keywords: neuron ; learning Reference EPFL-CONF-82314 Record created on 2006-03-10, modified on 2... more Keywords: neuron ; learning Reference EPFL-CONF-82314 Record created on 2006-03-10, modified on 2017-05-10
An Optical Tresholding Perceptron
<title>Noninvasive measurement of ion currents in plasma-assisted processes using an optical fiber Faraday ring ammeter</title>
In-Process Optical Measurements and Industrial Methods, 1990
ABSTRACT The efficiency of plasma assisted deposition processes such as reactive ion plating with... more ABSTRACT The efficiency of plasma assisted deposition processes such as reactive ion plating with regard to the densification of the deposited thin films depends strongly on the arrival rate ratio of ionized species (atoms molecules) to the total influx of vaporized coating material. While it is relatively easy to measure ion beam currents produced by an auxiliary ion beam source (for example a Kaufman gun) it is much more difficult to measure ion currents in plasma processes. Typical probe measurements change the plasma conditions almost instantaneously. An optical fiber Faraday ring ammeter initially developed for space plasma research provides for a non-invasive measurement of ion currents present in plasma assisted deposition processes. We will be discussing the principles and the potential use of such a device in a high vacuum box coater equipped for low voltage reactive ion plating deposition. 1.
Polarization noise in optical fiber Faraday ring ammeters : a dissertation /
Thesis (Ph. D.)--University of Alabama in Huntsville, 1991. Typescript (photocopy). Includes bibl... more Thesis (Ph. D.)--University of Alabama in Huntsville, 1991. Typescript (photocopy). Includes bibliographical references.
An adaptive multilayer dual-wavelength optical neural network design with all-optical forward pro... more An adaptive multilayer dual-wavelength optical neural network design with all-optical forward propagation, based on a large number of modifiable optical interconnections and a special weight discretization algorithm to compensate for em noise, is described. The presentation of input and interconnection weights is performed by liquid crystal television screens, and optical thresholding at the hidden layer by a liquid crystal light valve.
3-D Morphology and Viability Status Imaging of Tissue Culture
Proposal to Defence Health Agency, 2011
DESCRIPTION Keywords: three-dimensional characterization, tissue viability, engineered tissue ass... more DESCRIPTION Keywords: three-dimensional characterization, tissue viability, engineered tissue assessment, tissue engineering, imaging
Intelligent Optical Systems (IOS) proposes to develop a multimodal measurement tool to provide an assessment of the overall state of engineered soft tissue and its maturity for transplantation. The proposed multimodal system will provide continuous, real time, nondestructive, quantitative assessment of growing soft tissue cultures by measuring several critical parameters that are indicative of tissue health, namely: tissue morphology using optical coherence tomography (OCT), ultrasound (US) for deeper imaging, and tissue viability by means of optical fluorescence excitation. This multimodal technique, combined with sophisticated image processing tools, will be capable of non-invasively assessing the neovascularization, cell state, viability, and microstructure of the tissue, rendering a quantitative indication of the tissue's health as it grows. IOS's proposed multimodal optical diagnostic probe will add a viability imaging capability to the structural, morphological imaging OCT probe currently being developed. The proposed novel diagnostics tool will permit the complete characterization of healthy and unhealthy tissue on the basis of tissue density, as well as molecular composition.
Detecting the Onset of Fire in an Aircraft by Employing Correlation Spectroscopy
The cause of aircraft fire and locations of the fires are numerous. Worldwide, numerous in-flight... more The cause of aircraft fire and locations of the fires are numerous. Worldwide, numerous in-flight fires have been passenger initiated, the prime location being the lavatory areas. Most in-flight fires in commercial carriers are of electrical origin and cigarettes. A cargo bay fire can be caused by a variety of reasons. The sheer number of different types of cargo makes it difficult to identify the origin, especially when the fire reaches the catastrophic level. The damage can be minimized, and fire can be suppressed effectively if a warning system for the onset of fire is available for onboard monitoring.
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Papers by Indu FieslerSaxena
Intelligent Optical Systems (IOS) proposes to develop a multimodal measurement tool to provide an assessment of the overall state of engineered soft tissue and its maturity for transplantation. The proposed multimodal system will provide continuous, real time, nondestructive, quantitative assessment of growing soft tissue cultures by measuring several critical parameters that are indicative of tissue health, namely: tissue morphology using optical coherence tomography (OCT), ultrasound (US) for deeper imaging, and tissue viability by means of optical fluorescence excitation. This multimodal technique, combined with sophisticated image processing tools, will be capable of non-invasively assessing the neovascularization, cell state, viability, and microstructure of the tissue, rendering a quantitative indication of the tissue's health as it grows. IOS's proposed multimodal optical diagnostic probe will add a viability imaging capability to the structural, morphological imaging OCT probe currently being developed. The proposed novel diagnostics tool will permit the complete characterization of healthy and unhealthy tissue on the basis of tissue density, as well as molecular composition.