Andrew Rollins | Case Western Reserve University (original) (raw)

Papers by Andrew Rollins

(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005

... From CFA7 © 2005 OSA/CLEO 2005 Page 2. ... We placed the mirror at 3.07mm, aligned the system... more ... From CFA7 © 2005 OSA/CLEO 2005 Page 2. ... We placed the mirror at 3.07mm, aligned the system and recorded the spectrum. Using a micrometer stage we laterally displaced the camera by 7 CFA7 © 2005 OSA/CLEO 2005 Page 3. ...

Handbook of Optical Coherence Tomography, 2001

Color Doppler optical coherence tomography (CDOCT) is a functional extension of optical coherence... more Color Doppler optical coherence tomography (CDOCT) is a functional extension of optical coherence tomography that can image flow in turbid media. We have developed a CDOCT system capable of imaging flow in real time. Doppler processing of the analog signal is accomplished in hardware in the time domain using a novel autocorrelation technique. This Doppler processing method was implemented arm

Journal of biomedical optics, 2016

We developed robust, three-dimensional methods, as opposed to traditional A-line analysis, for es... more We developed robust, three-dimensional methods, as opposed to traditional A-line analysis, for estimating the optical properties of calcified, fibrotic, and lipid atherosclerotic plaques from in vivo coronary artery intravascular optical coherence tomography clinical pullbacks. We estimated attenuation [Formula: see text] and backscattered intensity [Formula: see text] from small volumes of interest annotated by experts in 35 pullbacks. Some results were as follows: noise reduction filtering was desirable, parallel line (PL) methods outperformed individual line methods, root mean square error was the best goodness-of-fit, and [Formula: see text]-trimmed PL ([Formula: see text]-T-PL) was the best overall method. Estimates of [Formula: see text] were calcified ([Formula: see text]), fibrotic ([Formula: see text]), and lipid ([Formula: see text]), similar to those in the literature, and tissue classification from optical properties alone was promising.

Urology, Jan 5, 2011

OBJECTIVES-To verify the ability to identify the layered structures of ureteral wall and to image... more OBJECTIVES-To verify the ability to identify the layered structures of ureteral wall and to image a segment of ureter in three dimensions with a high speed endoscopic optical coherence tomography (EOCT).

Conference on Lasers and Electro Optics 2003 Cleo 03, 2003

... Cameron J. Pedersen, Siavash Yazdanfar, Volker Westphal, Andrew M. Rollins Department of Biom... more ... Cameron J. Pedersen, Siavash Yazdanfar, Volker Westphal, Andrew M. Rollins Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106 Phone: 216-844-3298; Fax: 216-844-8011; email:cpedersen@cwru.edu ... 2003 OSA/CLEO 2003 ...

Bailliere X027 S Best Practice and Research in Clinical Gastroenterology, Apr 30, 2001

Light interacts with tissue in a variety of ways, including absorption, fluorescence, elastic sca... more Light interacts with tissue in a variety of ways, including absorption, fluorescence, elastic scattering and Raman scattering. These interactions enable a number of promising technologies for endoscopic diagnosis of pre-malignancy, including chromoscopy; fluorescence, scattering and Raman spectroscopies; and optical coherence tomography. Although still in various stages of technical development and clinical trials, these optical diagnostic techniques are demonstrating strong potential to significantly enhance the clinical endoscopist's ability to detect dysplasia in gastrointestinal mucosae.

Optics Communications, Apr 1, 2008

We demonstrate a compact, inexpensive, and reliable fiber-coupled light source with broad bandwid... more We demonstrate a compact, inexpensive, and reliable fiber-coupled light source with broad bandwidth and sufficient power at 1300 nm for high resolution optical coherence tomography (OCT) imaging in real-time applications. By combining four superluminescent diodes (SLEDs) with different central wavelengths, the light source has a bandwidth of 145 nm centered at 1325 nm with over 10 mW of power. OCT images of an excised stage 30 embryonic chick heart acquired with our combined SLED light source (<5 μm axial resolution in tissue) are compared with images obtained with a single SLED source (˜10 μm axial resolution in tissue). The high resolution OCT system with the combined SLED light source provides better image quality (smaller speckle noise) and a greater ability to observe fine structures in the embryonic heart.

Optics Letters, Mar 1, 2003

We describe a novel technique for contrast enhancement in optical coherence tomography (OCT) that... more We describe a novel technique for contrast enhancement in optical coherence tomography (OCT) that makes possible molecular-specific imaging for what is believed to be the first time. A pump-probe technique is employed in which a pulsed pump laser is tuned to ground-state absorption in a molecule of interest. The location of the target molecule population is derived from the resulting transient absorption of OCT sample-arm light acting as probe light. A signal processing technique for three-dimensional localization of the transient absorption signal is described, and preliminary results exhibiting OCT contrast from methylene blue dye in multilayer and scattering phantoms are presented.

Coherence Domain Optical Methods in Biomedical Science and Clinical Applications Iv, Apr 1, 2000

The most straightforward interferometer for optical coherence tomography (OCT) is a simple Michel... more The most straightforward interferometer for optical coherence tomography (OCT) is a simple Michelson interferometer. A low-coherence source illuminates the interferometer. The light is split by a 50/50 beamsplitter into a sample and a reference path. Light retro reflected from the reference and the sample is recombined at the beamsplitter and half is collected by a photodetetor in the detection arm of the interferometer. Half of the light is returned towards the source, where it is lost. In addition, the reference arm light is typically attenuated by orders of magnitude in order to improve signal to noise ratio. Thus, using this typical configuration, virtually 75 percent of the optical power supplied by the source is not used for image formation. We present a family of novel interferometer designs incorporating optical circulators, unbalanced couplers, and/or balanced detection which are designed to optimize optical power efficiency and circulators, unbalanced couplers, and/or balance detection which are designed to optimize optical power efficiency and system signal to noise ratio. We evaluate the expected performance of the novel interferometers as compared with the standard Michelson interferometer. We review signal and noise sources important for the design of OCT interferometers, and specify the design equations for evaluation and optimization of signal to noise ratio. This analysis, based on sound, experimentally verified literature, predicts improved sensitivity for all of the new interferometer designs.

The Journal of Innovations in Cardiac Rhythm Management, 2011

We report the first in vivo use of optical coherence tomography (OCT), a highresolution (,10 mm) ... more We report the first in vivo use of optical coherence tomography (OCT), a highresolution (,10 mm) real-time imaging technology, to scan subendocardial tissue and to monitor radiofrequency (RF) lesion formation. Endocardial imaging during an open chest procedure in a female pig was conducted with a forward imaging catheter with a Fourier Domain OCT system at 20 frames per second. Images of the endocardial surface and subendocardial tissue were obtained when the catheter was in direct contact with the endocardial surface. The formation and progressive increase in size of cavities within the myocardium were observed in the OCT images when a steam pop was audible. Our initial findings suggest that imaging with a forward scanning OCT catheter can assess tip electrode-tissue interface contact, image subsurface myocardial structure, and visualize dynamic effects of intramural RF energy delivery.

This report presents an advanced analysis of the optics of optical coherence tomography (OCT) sys... more This report presents an advanced analysis of the optics of optical coherence tomography (OCT) systems. Study indicates that spectral filtering functions are contributed by the system optics, the coupling efficiency of both sample and reference arms, and the position of the sample relative to the optics. Simulations by advanced optical software, experiments on two existing OCT systems and the modified theoretical formula demonstrate that the different optics give different filtering functions. These filtering function narrow down the spectrum, shift the center of the spectrum and drop the amplitude of the intensity. Defining a composite standard deviation and a composite center wavelength of the two filtered spectra, we developed a new formula to describe the interference term of OCT, which clearly indicates the detail of the filtering function. An experiment in an extreme condition has been investigated in one of our existing OCT systems. We placed a narrow bandwidth filter into the reference arm. The filter has a center wavelength of 1313.6 nm with a full bandwidth of 6.4nm. The light source has a center wavelength of 1292nm with a bandwidth of 34nm. Experimental resolutions are 19 microns and 85 microns, with and without filter respectively. The calculations are 21.6 and 85.5 microns, respectively, using our new formula.

Optics Letters a Publication of the Optical Society of America, Nov 1, 2004

We describe a novel imaging technique, second-harmonic-generation optical coherence tomography (S... more We describe a novel imaging technique, second-harmonic-generation optical coherence tomography (SHOCT). This technique combines the spatial resolution and depth penetration of optical coherence tomography (OCT) with the molecular sensitivity of second-harmonic-generation spectroscopy. As a consequence of the coherent detection required for OCT, polarization-resolved images arise naturally. We demonstrate this new technique on a skin sample from the belly of Icelandic salmon, acquiring polarization-resolved SHOCT and OCT images simultaneously.

Yan Li and David Huang Division of Ophthalmology The Cleveland Clinic Foundation 9500 Euclid Aven... more Yan Li and David Huang Division of Ophthalmology The Cleveland Clinic Foundation 9500 Euclid Avenue Cleveland, OH 44195 huangd@ccf.org ... Joseph A. Izatt Department of Biomedical Engineering Duke University Box 90281 Durham, NC 27708-0281 jizatt@duke.edu