ABSTRACT We are developing an advanced computer-controlled digital optoelectronic holographic sys... more ABSTRACT We are developing an advanced computer-controlled digital optoelectronic holographic system (DOEHS) with the ability to measure both shape and acoustically induced deformations of the tympanic membrane of several species, including humans. The DOEHS have been deployed for testing and use in clinical environment. The DOEHS consists of laser delivery (LD), optical head (OH), sound presentation (SP), computing platform (CP), and a mechatronic otoscope positioner (MOP) subsystems. In this paper, we present advances in our development of the MOP subsystem, which is capable of positioning the OH subsystem near the patient’s ear and maintaining of its relative position and orientation during holographic eardrum examinations. Our work focuses on the development and implementation of various approaches for mechanical stabilization of the MOP-OH subsystems, including custom designed packaging of the OH as well as automatic interferometric compensation against measuring disturbances induced by periodic oscillations, such as those produced by heartbeat and breathing of a patient during examination. We present preliminary results of our investigations of acoustically induced motions on tympanic membranes by measurements with our DOEHS enabled with a structurally stable MOP subsystem. Keywordsstructural stabilization-mechatronics-middle ear mechanics-otology-shape and deformation measurements
The malleus and incus in the human middle ear are linked by the incudo-malleolar joint (IMJ). The... more The malleus and incus in the human middle ear are linked by the incudo-malleolar joint (IMJ). The mobility of the human IMJ under physiologically relevant acoustic stimulation and its functional role in middle-ear sound transmission are still debated. In this study, spatial stapes motions were measured during acoustic stimulation (0.25-8 kHz) in six fresh human temporal bones for two conditions of the IMJ: (1) normal IMJ and (2) IMJ with experimentally-reduced mobility. Stapes velocity was measured at multiple points on the footplate using a scanning laser Doppler vibrometry (SLDV) system, and the 3D motion components were calculated under both conditions of the IMJ. The artificial reduction of the IMJ mobility was confirmed by measuring the relative motion between the malleus and the incus. The magnitudes of the piston-like motion of the stapes increased with the reduced IMJ mobility above 2 kHz. The increase was frequency dependent and was prominent from 2 to 4 kHz and at 5.5 kHz....
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
ABSTRACT This project investigates an innovative approach to imaging with Micro Electro-Mechanica... more ABSTRACT This project investigates an innovative approach to imaging with Micro Electro-Mechanical Systems (MEMS) based devices. By using a Linnik interferometer and advanced phase unwrapping algorithms for processing data, the feasibility of generating high-resolution grayscale images in real-time was proven with an array of individually addressable MEMS micro-mirrors. Further investigations on a thermal imaging detector consisting of an array of pixels defined by surface micromachined bimaterial beam structures were carried out. A thermal loading fixture was manufactured and incorporated into the interferometer setup, which was also optimized to provide high measuring resolution. Interferometric images were collected at several temperatures in order to determine the beams’ response as a function of temperature, which successfully demonstrated the suitability of the detector to imaging with high-sensitivity and with a linear response. Experimental results were used with analytical and computational models to further predict the thermo-mechanical characteristics of the beams and to perform parametric investigations and optimization of their design. Further developments will consist of integrating the detector into a highly advanced, completely mechanical, imaging device having mK thermal resolution. The availability of such device will greatly improve current thermal imaging technology. Keywordsinterferometry-infrared imaging-MEMS-metrology-thermoelasticity-micromachining
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
The abilities to increase precision of surgical procedures by tracking real-time motions, accurat... more The abilities to increase precision of surgical procedures by tracking real-time motions, accurately measuring the mechanical properties of complex 3D geometries, and tracking deformations of components over time, among many other applications, depend on the availability of robust, high-speed, full-field-of-view, 3D shape measurement systems. In this paper, we present advances in our development of a high-speed 3D shape measurement system based on fringe projection. The system consists of a high-speed projector, with speeds up to 20,000 frames per second, that is integrated with a CCD camera to provide full-field-of-view information. By using high-speed projection of sinusoidal fringe patterns with varying spatial densities together with temporal phase unwrapping algorithms that we are developing, we are able to compute and display unwrapped phase maps at video rates, which enable the capability to perform absolute shape measurements of components. We present representative results obtained with our system as we have applied it to art conservation and to biomedical imaging. Results validate system capabilities as a high-speed method of dynamically gathering, analyzing, and displaying shape information.
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
ABSTRACT Holographic interferometric methods for measuring 3D displacement fields require at leas... more ABSTRACT Holographic interferometric methods for measuring 3D displacement fields require at least three individual sensitivity vectors. Methods based on multiple directions of illumination have limited application when studying transient phenomena, including, but not limited to, measurements of biological tissues that have temporally-varying responses, such as the eardrum or Tympanic Membrane (TM). Therefore, to measure 3D displacements in such applications, all the measurements have to be done concomitantly. In this paper, we propose a new multiple illumination direction approach to measure 3D displacements from a single-shot hologram that contains displacement information from three sensitivity vectors. In our approach, the hologram of an object of interest is recorded with three simultaneous incoherently-superimposed pairs of reference and object beams, such that the modulation image corresponding to each illumination direction is reconstructed at a particular position on the image. Incoherent superposition of the beams is implemented by using three different laser diodes. Because of the differences in the position of each reference beam and wavelength of each pair of beams, the reconstruction distance and magnification of each sensitivity vector are different. We, therefore, developed and implemented a registration algorithm to accurately translate individual views into a single global coordinate system. Representative results will include measurements of shape and sound-induced 3D displacements of the TM.
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
ABSTRACT Microelectromechanical Systems (MEMS) technologies have allowed the development of novel... more ABSTRACT Microelectromechanical Systems (MEMS) technologies have allowed the development of novel, uncooled infrared imaging detectors consisting of arrays of bi-material structures that deflect linearly as a function of temperature associated with infrared radiation from a scene. An optical readout system can be used to measure the deformation of the structures based on reflected light, and offers several advantages over the microbolometer sensors that are currently in widespread use including the ability to sense each structure without the need for complex addressing and sensing circuitry in the array. This leads to lower production costs, easier scalability, and reduced conduction between the substrate and individual sensing elements. However, it has been shown that optical readout methods based on reflectometry suffer from the effects of low array uniformity and offer only a qualitative response. Our previous work has shown that live digital holography can be used to compensate for initial non-uniformity across a small subsection of a representative array of sensing elements, and interferometric techniques have been used to observe a responsivity of 1.5 nm/K along with an NEDT of 220 mK. The current work explores the use of unpowered interferometric techniques such as Nomarski differential interference and live phase holography to overcome the previously mentioned limitations of reflectometry based measurements in order to demonstrate the viability of creating an infrared direct viewer.
In this paper, we propose a multi-pulsed double exposure (MPDE) acquisition method to quantify in... more In this paper, we propose a multi-pulsed double exposure (MPDE) acquisition method to quantify in full-field-of-view the transient (i.e., >10 kHz) acoustically induced nanometer scale displacements of the human tympanic membrane (TM or eardrum). The method takes advantage of the geometrical linearity and repeatability of the TM displacements to enable high-speed measurements with a conventional camera (i.e., <20 fps). The MPDE is implemented on a previously developed digital holographic system (DHS) to enhance its measurement capabilities, at a minimum cost, while avoiding constraints imposed by the spatial resolutions and dimensions of high-speed (i.e., >50 kfps) cameras. To our knowledge, there is currently no existing system to provide such capabilities for the study of the human TM. The combination of high temporal (i.e., >50 kHz) and spatial (i.e., >500k data points) resolutions enables measurements of the temporal and frequency response of all points across the ...
Acoustically-induced vibrations of the Tympanic Membrane (TM) play a primary role in the hearing ... more Acoustically-induced vibrations of the Tympanic Membrane (TM) play a primary role in the hearing process, in that these motions are the initial mechanical response of the ear to airborne sound. Characterization of the shape and 3D displacement patterns of the TM is a crucial step to a better understanding of the complicated mechanics of sound reception by the ear. In this paper, shape and sound-induced 3D displacements of the TM in cadaveric chinchillas are measured by a lensless Dual-Wavelength Digital Holography system (DWDHS). The DWDHS consists of Laser Delivery (LD), Optical Head (OH), and Computing Platform (CP) subsystems. Shape measurements are performed in double-exposure mode and with the use of two wavelengths of a tunable laser while nanometer-scale displacements are measured along a single sensitivity direction and with a constant wavelength. In order to extract the three principal components of displacement in full-field-of-view, and taking into consideration the anato...
Current ear examination procedures provide mostly qualitative information which results in insuff... more Current ear examination procedures provide mostly qualitative information which results in insufficient or erroneous description of the patient&#39;s hearing. Much more quantitative and accurate results can be achieved with a holographic otoscope system currently under development. Various ways of accurate positioning and stabilization of the system in real-life conditions are being investigated by this project in an attempt to bring
ABSTRACT We are developing an advanced computer-controlled digital optoelectronic holographic sys... more ABSTRACT We are developing an advanced computer-controlled digital optoelectronic holographic system (DOEHS) with the ability to measure both shape and acoustically induced deformations of the tympanic membrane of several species, including humans. The DOEHS have been deployed for testing and use in clinical environment. The DOEHS consists of laser delivery (LD), optical head (OH), sound presentation (SP), computing platform (CP), and a mechatronic otoscope positioner (MOP) subsystems. In this paper, we present advances in our development of the MOP subsystem, which is capable of positioning the OH subsystem near the patient’s ear and maintaining of its relative position and orientation during holographic eardrum examinations. Our work focuses on the development and implementation of various approaches for mechanical stabilization of the MOP-OH subsystems, including custom designed packaging of the OH as well as automatic interferometric compensation against measuring disturbances induced by periodic oscillations, such as those produced by heartbeat and breathing of a patient during examination. We present preliminary results of our investigations of acoustically induced motions on tympanic membranes by measurements with our DOEHS enabled with a structurally stable MOP subsystem. Keywordsstructural stabilization-mechatronics-middle ear mechanics-otology-shape and deformation measurements
The malleus and incus in the human middle ear are linked by the incudo-malleolar joint (IMJ). The... more The malleus and incus in the human middle ear are linked by the incudo-malleolar joint (IMJ). The mobility of the human IMJ under physiologically relevant acoustic stimulation and its functional role in middle-ear sound transmission are still debated. In this study, spatial stapes motions were measured during acoustic stimulation (0.25-8 kHz) in six fresh human temporal bones for two conditions of the IMJ: (1) normal IMJ and (2) IMJ with experimentally-reduced mobility. Stapes velocity was measured at multiple points on the footplate using a scanning laser Doppler vibrometry (SLDV) system, and the 3D motion components were calculated under both conditions of the IMJ. The artificial reduction of the IMJ mobility was confirmed by measuring the relative motion between the malleus and the incus. The magnitudes of the piston-like motion of the stapes increased with the reduced IMJ mobility above 2 kHz. The increase was frequency dependent and was prominent from 2 to 4 kHz and at 5.5 kHz....
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
ABSTRACT This project investigates an innovative approach to imaging with Micro Electro-Mechanica... more ABSTRACT This project investigates an innovative approach to imaging with Micro Electro-Mechanical Systems (MEMS) based devices. By using a Linnik interferometer and advanced phase unwrapping algorithms for processing data, the feasibility of generating high-resolution grayscale images in real-time was proven with an array of individually addressable MEMS micro-mirrors. Further investigations on a thermal imaging detector consisting of an array of pixels defined by surface micromachined bimaterial beam structures were carried out. A thermal loading fixture was manufactured and incorporated into the interferometer setup, which was also optimized to provide high measuring resolution. Interferometric images were collected at several temperatures in order to determine the beams’ response as a function of temperature, which successfully demonstrated the suitability of the detector to imaging with high-sensitivity and with a linear response. Experimental results were used with analytical and computational models to further predict the thermo-mechanical characteristics of the beams and to perform parametric investigations and optimization of their design. Further developments will consist of integrating the detector into a highly advanced, completely mechanical, imaging device having mK thermal resolution. The availability of such device will greatly improve current thermal imaging technology. Keywordsinterferometry-infrared imaging-MEMS-metrology-thermoelasticity-micromachining
Conference Proceedings of the Society for Experimental Mechanics Series, 2011
The abilities to increase precision of surgical procedures by tracking real-time motions, accurat... more The abilities to increase precision of surgical procedures by tracking real-time motions, accurately measuring the mechanical properties of complex 3D geometries, and tracking deformations of components over time, among many other applications, depend on the availability of robust, high-speed, full-field-of-view, 3D shape measurement systems. In this paper, we present advances in our development of a high-speed 3D shape measurement system based on fringe projection. The system consists of a high-speed projector, with speeds up to 20,000 frames per second, that is integrated with a CCD camera to provide full-field-of-view information. By using high-speed projection of sinusoidal fringe patterns with varying spatial densities together with temporal phase unwrapping algorithms that we are developing, we are able to compute and display unwrapped phase maps at video rates, which enable the capability to perform absolute shape measurements of components. We present representative results obtained with our system as we have applied it to art conservation and to biomedical imaging. Results validate system capabilities as a high-speed method of dynamically gathering, analyzing, and displaying shape information.
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
ABSTRACT Holographic interferometric methods for measuring 3D displacement fields require at leas... more ABSTRACT Holographic interferometric methods for measuring 3D displacement fields require at least three individual sensitivity vectors. Methods based on multiple directions of illumination have limited application when studying transient phenomena, including, but not limited to, measurements of biological tissues that have temporally-varying responses, such as the eardrum or Tympanic Membrane (TM). Therefore, to measure 3D displacements in such applications, all the measurements have to be done concomitantly. In this paper, we propose a new multiple illumination direction approach to measure 3D displacements from a single-shot hologram that contains displacement information from three sensitivity vectors. In our approach, the hologram of an object of interest is recorded with three simultaneous incoherently-superimposed pairs of reference and object beams, such that the modulation image corresponding to each illumination direction is reconstructed at a particular position on the image. Incoherent superposition of the beams is implemented by using three different laser diodes. Because of the differences in the position of each reference beam and wavelength of each pair of beams, the reconstruction distance and magnification of each sensitivity vector are different. We, therefore, developed and implemented a registration algorithm to accurately translate individual views into a single global coordinate system. Representative results will include measurements of shape and sound-induced 3D displacements of the TM.
Conference Proceedings of the Society for Experimental Mechanics Series, 2014
ABSTRACT Microelectromechanical Systems (MEMS) technologies have allowed the development of novel... more ABSTRACT Microelectromechanical Systems (MEMS) technologies have allowed the development of novel, uncooled infrared imaging detectors consisting of arrays of bi-material structures that deflect linearly as a function of temperature associated with infrared radiation from a scene. An optical readout system can be used to measure the deformation of the structures based on reflected light, and offers several advantages over the microbolometer sensors that are currently in widespread use including the ability to sense each structure without the need for complex addressing and sensing circuitry in the array. This leads to lower production costs, easier scalability, and reduced conduction between the substrate and individual sensing elements. However, it has been shown that optical readout methods based on reflectometry suffer from the effects of low array uniformity and offer only a qualitative response. Our previous work has shown that live digital holography can be used to compensate for initial non-uniformity across a small subsection of a representative array of sensing elements, and interferometric techniques have been used to observe a responsivity of 1.5 nm/K along with an NEDT of 220 mK. The current work explores the use of unpowered interferometric techniques such as Nomarski differential interference and live phase holography to overcome the previously mentioned limitations of reflectometry based measurements in order to demonstrate the viability of creating an infrared direct viewer.
In this paper, we propose a multi-pulsed double exposure (MPDE) acquisition method to quantify in... more In this paper, we propose a multi-pulsed double exposure (MPDE) acquisition method to quantify in full-field-of-view the transient (i.e., >10 kHz) acoustically induced nanometer scale displacements of the human tympanic membrane (TM or eardrum). The method takes advantage of the geometrical linearity and repeatability of the TM displacements to enable high-speed measurements with a conventional camera (i.e., <20 fps). The MPDE is implemented on a previously developed digital holographic system (DHS) to enhance its measurement capabilities, at a minimum cost, while avoiding constraints imposed by the spatial resolutions and dimensions of high-speed (i.e., >50 kfps) cameras. To our knowledge, there is currently no existing system to provide such capabilities for the study of the human TM. The combination of high temporal (i.e., >50 kHz) and spatial (i.e., >500k data points) resolutions enables measurements of the temporal and frequency response of all points across the ...
Acoustically-induced vibrations of the Tympanic Membrane (TM) play a primary role in the hearing ... more Acoustically-induced vibrations of the Tympanic Membrane (TM) play a primary role in the hearing process, in that these motions are the initial mechanical response of the ear to airborne sound. Characterization of the shape and 3D displacement patterns of the TM is a crucial step to a better understanding of the complicated mechanics of sound reception by the ear. In this paper, shape and sound-induced 3D displacements of the TM in cadaveric chinchillas are measured by a lensless Dual-Wavelength Digital Holography system (DWDHS). The DWDHS consists of Laser Delivery (LD), Optical Head (OH), and Computing Platform (CP) subsystems. Shape measurements are performed in double-exposure mode and with the use of two wavelengths of a tunable laser while nanometer-scale displacements are measured along a single sensitivity direction and with a constant wavelength. In order to extract the three principal components of displacement in full-field-of-view, and taking into consideration the anato...
Current ear examination procedures provide mostly qualitative information which results in insuff... more Current ear examination procedures provide mostly qualitative information which results in insufficient or erroneous description of the patient&#39;s hearing. Much more quantitative and accurate results can be achieved with a holographic otoscope system currently under development. Various ways of accurate positioning and stabilization of the system in real-life conditions are being investigated by this project in an attempt to bring
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