1. Hrebesh M. Subhash

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    1. Mentioned In 32 Articles

    2. Feature Of The Week 5/19/13: Using Optical Coherence Tomography For Anti-Spoof Fingerprint Detection

      Feature Of The Week 5/19/13: Using Optical Coherence Tomography For Anti-Spoof Fingerprint Detection

      Fingerprint biometrics, including automated fingerprint identification systems (AFIS), currently occupy two-thirds of the biometric market and are expected to remain the dominant player in this area. The technology can be integrated into small, compact devices and the instruments are relatively fast. However, the overall success of using fingerprints for identification and verification purposes greatly depends upon the quality of the fingerprints initially enrolled. For example, fingerprints captured from older people are significantly lower quality than those from younger people due primarily to ridge-wearing and difficulty of interacting effectively with conventional fingerprint scanners. The ramification is that the problem of obtaining ...

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    3. Feasibility of correlation mapping optical coherence tomography (cmOCT) for anti-spoof sub-surface fingerprinting

      Feasibility of correlation mapping optical coherence tomography (cmOCT) for anti-spoof sub-surface fingerprinting

      We propose the use of correlation mapping optical coherence tomography (cmOCT) to deliver additional biometrics associated with the finger that could complement existing fingerprint technology for law enforcement applications. The current study extends the existing fingerprint paradigm by measuring additional biometrics associated with sub-surface finger tissue such as sub-surface fingerprints, sweat glands, and the pattern of the capillary bed to yield a user-friendly cost effective and anti-spoof multi-mode biometric solution associated with the finger. To our knowledge no other method has been able to capture sub-surface fingerprint, papillary pattern and horizontal vessel pattern in a single scan or to show ...

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    4. Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea

      Reflective type objective based spectral-domain phase-sensitive optical coherence tomography for high-sensitive structural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea
      ...tural and functional imaging of cochlear microstructures through intact bone of an excised guinea pig cochlea Hrebesh M. Subhash ; Ruikang K. Wang ; Fangyi Chen ; Alfred L. Nuttall; Reflective type objective based spectr...
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    5. Feature Of The Week 3/17/13: Using Optical Coherence Tomography to Study Mechanisms of Hearing

      Feature Of The Week 3/17/13: Using Optical Coherence Tomography to Study Mechanisms of Hearing
      ...within the organ of Corti at a subnanometer scale: a preliminary study”, J. Biomed. Opt. 15, 056005 (2010).5. Hrebesh M. Subhash, Anh Nguyen-Huynh, Ruikang K. Wang, Steven L. Jacques and Alfred L. Nuttall, "Feasibility o...
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    6. Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography

      Measurement of in vivo basal-turn vibrations of the organ of Corti using phase-sensitive Fourier domain optical coherence tomography
      ... Fourier domain optical coherence tomography Sripriya Ramamoorthy ; Yuan Zhang ; Tracy Petrie ; Fangyi Chen ; Hrebesh M. Subhash ; Niloy Choudhury ; Ruikang Wang ; Steven L. Jacques ; Alfred L. Nuttall; Measurement of in...
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    7. Depth-resolved dual-beamlet vibrometry based on Fourier domain low coherence interferometry

      Depth-resolved dual-beamlet vibrometry based on Fourier domain low coherence interferometry

      We present an optical vibrometer based on delay-encoded, dual-beamlet phase-sensitive Fourier domain interferometric system to provide depth-resolved subnanometer scale vibration information from scattering biological specimens. System characterization, calibration, and preliminary vibrometry with biological specimens were performed. The proposed system has the potential to provide both amplitude and direction of vibration of tissue microstructures on a single two-dimensional plane.

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    8. Feature Of The Week 6/17/12: Middle Ear Vibrometry of Human Cadaver Temporal Bone with Spectral Domain Phase-Sensitive Optical Coherence Tomography

      Feature Of The Week 6/17/12: Middle Ear Vibrometry of Human Cadaver Temporal Bone with Spectral Domain Phase-Sensitive Optical Coherence Tomography

      Hearing loss is the most frequent sensory deficit in the human population, affecting more than 250 million people in the world. The National Center for Health Statistics estimates that 37 million adults (17%) in the United States have hearing difficulty. Analysis of a large database of audiometric records from the University of Minnesota reveals that 39% of patients diagnosed with hearing loss have conductive hearing loss (CHL) either alone (15%) or in combination with SNHL (24%). There are several contemporary audiological tests that are commonly used to diagnose middle ear function for CHL. However, these contemporary tests of middle ear ...

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    9. Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

      Feasibility of spectral-domain phase-sensitive optical coherence tomography for middle ear vibrometry

      We describe a novel application of spectral-domain phase-sensitive optical coherence tomography (SD PS-OCT) to detect the tiny motions of the middle ear structures, such as the tympanic membrane and ossicular chain, and their morphological features for differential diagnosis of CHL. This technique has the potential to provide meaningful vibration of ossicles with a vibration sensitivity of ∼ 0.5  nm at 1 kHz of acoustic stimulation. To the best of our knowledge, this is the first demonstration of depth-resolved vibration imaging of ossicles with a PS-OCT system at a nanometer scale.

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    10. Full-Field and Single-Shot Full-Field Optical Coherence Tomography: A Novel Technique for Biomedical Imaging Applications

      Full-Field and Single-Shot Full-Field Optical Coherence Tomography: A Novel Technique for Biomedical Imaging Applications

      Since its introduction, optical coherence tomography (OCT) technology has advanced dramatically in various field of both clinical and fundamental research. Full-field and Single-shot full-field OCT (FF-OCT and SS-FF-OCT) are alternative OCT concepts, which aims to improve the image acquisition speed and to simplify the optical setup of conventional point-scan OCT by realizing direct line field or full-field sample imaging onto an array or line detector such as CCD or CMOS camera. FF-OCT and SS-FF-OCT are based on bulk optics Linnik-type Michelson interferometer with relatively high numerical aperture (NA) microscopic objectives. This paper will give you an overview of the principle ...

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    11. Optical detection of indocyanine green encapsulated biocompatible poly (lactic-co-glycolic) acid nanoparticles with photothermal optical coherence tomography

      Optical detection of indocyanine green encapsulated biocompatible poly (lactic-co-glycolic) acid nanoparticles with photothermal optical coherence tomography

      We describe a functional imaging paradigm that uses photothermal optical coherence tomography (PT-OCT) to detect indocyanine green (ICG)-encapsulated biocompatible poly(lactic-co-glycolic) acid (PLGA) nanoparticles embedded in highly scattering tissue phantoms with high resolution and sensitivity. The ICG-loaded PLGA nanoparticles were fabricated using a modified emulsification solvent diffusion method. With a 20 kHz axial scan rate, PT-OCT based on spectral-domain interferometric configuration at 1310 nm was used to detect phase changes induced by a 808 nm photothermal excitation of ICG-encapsulated PLGA nanoparticles. An algorithm based on Fourier transform analysis of differential phase of the spectral interferogram was developed for detecting ...

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    12. Simultaneous depth-resolved imaging of sub-nanometer scale ossicular vibrations and morphological features of the human-cadaver middle ear with spectral-domain phase-sensitive optical coherence tomography

      Simultaneous depth-resolved imaging of sub-nanometer scale ossicular vibrations and morphological features of the human-cadaver middle ear with spectral-domain phase-sensitive optical coherence tomography

      We describe a novel method for the detection of the tiny motions of the middle ear (ME) ossicles and their morphological features with a spectral-domain phase sensitive optical coherence tomography (PS-OCT). Laser Doppler Vibrometry (LDV) and its variations are the most extensively used methods for studding the vibrational modes of the ME. However, most techniques are limited to single point analysis methods, and do not have the ability to provide depth resolved simultaneous imaging of multiple points on the ossicles especially with the intact eardrum. Consequently, the methods have the limited ability to provide relative vibration information at these points ...

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    13. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

      Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

      Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from ...

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    14. Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

      Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

      Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head ...

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  2. About Hrebesh M. Subhash

    Hrebesh M. Subhash

    Hrebesh Molly Subhash is with the Biophotonics & Imaging Lab in the School of Medicine at the Oregon Health & Science University. Hrebesh is currently a research associate in Biophotonics and Imaging Laboratory (BAIL), School of Medicine, OHSU Hospital at Portland, OR USA. He works with Prof. R. K. Wang, who is the director of BAIL. His current research activity involves the development of novel optical coherence domain imaging techniques for both anatomical and functional imaging.

    He received his Ph.D. degree in Human Sensing and Functional Sensor Engineering in 2008 from Yamagata University, Yonezawa, Japan. He earned his bachelor's degree in Applied Electronics from the University of Kerala in 1998; his master's in Applied Electronics from the University of Bharathiar in 2000; and his M. Phil in Photonics from the International School of Photonics at the Cochin University of Science and Technology in 2004.

    He was a member of Dr. P.K . Gupta's Biomedical Application Section of RRCAT , Indore. I worked with the Optical Imaging Laboratory led by Dr. Divaker Rao and played a key role in developing the first indigenous Optical Coherence Tomography setup in India.