Publications & Presentations

High-resolution retinal imaging: enhancement techniques

Mircea Mujat, Ankit Patel, Nicusor Iftimia, James D. Akula, Anne B. Fulton, and R. Daniel Ferguson
High-resolution retinal imaging: enhancement techniques
SPIE Photonics West, San Francisco, CA, (February 7 -12, 2015)

AO has achieved success in a range of applications in ophthalmology where microstructures need to be identified, counted, and mapped. Multiple images are averaged to improve the SNR or analyzed for temporal dynamics. For small patches, image registration by cross-correlation is straightforward. Larger images require more sophisticated registration techniques.

Strip-based registration has been used successfully for photoreceptor mosaic alignment in small patches; however, if the deformations along long strips are not simple displacements, averaging will actually degrade the images. We have applied non-rigid registration that significantly improves the quality of processed images for mapping cones and rods, and microvasculature in dark-field imaging. Local grid deformations account for local image stretching and compression due to a number of causes. Individual blood cells can be traced along capillaries in high-speed imaging (130 fps) and flow dynamics can be analyzed.

Dynamic 3-D chemical agent cloud mapping using a sensor constellation deployed on mobile platforms

Bogdan R. Cosofret, Daisei Konno, Dave Rossi, William J. Marinelli and Pete Seem
2014 SPIE DSS, 6-8 May 2014

Dynamic 3-D chemical agent cloud mapping using a sensor constellation deployed on mobile platforms

Utilization of advanced clutter suppression algorithms for improved standoff detection and identification of radionuclide threats

Bogdan R. Cosofret, Kirill Shokhirev, Phil Mulhall, David Payne, and Bernard Harris
2014 SPIE DSS, 6-8 May 2014

Utilization of advanced clutter suppression algorithms for improved standoff detection and identification of radionuclide threats

SWNT and MWNT from a Polymeric Electrospun Nanofiber Precursor

John D. Lennhoff, Ph.D.
Materials Research Society, 2014 MRS Fall Meeting & Exhibit, November 30 – December 5, 2014, Boston, MA

Carbon nanotubes (CNT) are expected to revolutionize a range of technologies because of their unique mechanical and electrical properties.

Using nanotubes in structural materials holds significant promise due to their extremely high modulus and tensile strength, however their cost, production rate and integration into a fiber form severely limit the current structural application opportunities. The high cost of CNT is tied to their slow, batch synthesis using vapor phase, vacuum processes. We report the investigation of the formation of carbon nanotubes from a polymeric precursor using an electrospinning production process. Electrospinning generates nanofibers at velocities up to 10 m/s from a single nozzle without a vacuum requirement, with the potential to generate CNT appropriate from structural and electrical applications. Our CNT formation concept is based upon Reactive Empirical Bond order calculations that show carbon nanofibers have a thermodynamic preference for the cylindrical graphite conformation. Simulations suggest that for small diameter carbon fibers, less than about 60 nm, the single wall and multi wall nanotubes (SWNT and MWNT) phases are thermodynamically favored relative to an amorphous or planar graphitic nanofiber structure. We have developed a novel process using continuous electrospun polyacrylonitrile (PAN) nanofibers as precursors to continuous SWNT and MWNT. The process for converting PAN nanofibers to SWNT's and MWNT's follows the process for typical carbon fiber manufacture. The PAN nanofibers, of 10 to 100 nm in diameter, are crosslinked by heating in air and then decomposed to carbon via simple pyrolysis in inert atmosphere. The pyrolyzed carbon nanofibers are then annealed to form the more energetically favorable SWNT or MWNT phase, depending upon the precursor diameter. We will discuss the process and characterization data.

Utilization of advanced clutter suppression algorithms for improved spectroscopic portal capability against radionuclide threats

Bogdan Cosofret, Kirill Shokhirev, and Phil Mulhall
2013 IEEE Conference on Technologies for Homeland Security, Waltham, MA, November 12-14, 2013

Utilization of advanced clutter suppression algorithms for improved spectroscopic portal capability against radionuclide threats