Graduate Exam Abstract

Keith Wernsing

Ph.D. Preliminary
May 16, 2018, 11:00 am - 1:00 pm
Odyssey Design Studio, Scott Bioengineering
Optical-to-RF Mapping for Multiphoton Imaging and Spectroscopy

Abstract: Current standard optical detectors like cameras and spectrometers are well-engineered workhorses of modern research. However, they
still exhibit certain limitations, such as imaging scattered light or resolving small spectral shifts. This work discusses two developments in
pulsed laser imaging and spectroscopy, both of which discard standard expensive optical detectors – namely, a camera and a
spectrometer - in place of a single pixel photodiode. For our imaging application, we spatiotemporally encode a pulsed laser before
sample interaction. The nonlinear laser-sample interaction and detection takes the form of spatial frequency projections, where the
bandwidth exceeds that of the focusing objective lens. The electronic signal is processed to reveal super-resolved images, and is general
to multiple modalities – most consequently, to harmonic generation, where very few super-resolution techniques operate. In our
spectroscopic application, we use a pair of laser pulse trains to excite and probe Raman vibrations in the sample. The information-bearing
probe pulse train is converted to an RF pulse train with a photodiode in order to measure small frequency shifts imparted by the object.
For both applications, we have developed robust fiber-based pulsed lasers, where front-end work in managing the pulse generation pays
off in terms of long-term operational sources.

Adviser: Randy Bartels
Co-Adviser: N/A
Non-ECE Member: Thomas Borch, Soil and Crop Sciences
Member 3: Jesse Wilson, ECE
Addional Members: Jeff Squier, ECE

[1] K. Wernsing, J. Field, S. Domingue, A. Allende-Motz, K. DeLuca, D. Levi, J. DeLuca, M. Young, J. Squier, R. Bartels, "Point spread function engineering with multiphoton SPIFI," Proc. SPIE 9713, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXIII, 971304 (2016)

[2] J. Field, K. Wernsing, S. Domingue, A. Allende-Motz, K. DeLuca, D. Levi, J. DeLuca, M. Young, J. Squier, R. Bartels, “Superresolved multiphoton microscopy,” Proceedings of the National Academy of Sciences, 113 (24), 6605-6610 (2016)

[3] D. Kuciauskas, K. Wernsing, S. A. Jensen, T. M. Barnes, T. H. Myers, and R. A. Bartels, "Analysis of Recombination in CdTe Heterostructures With Time-Resolved Two-Photon Excitation Microscopy," IEEE Journal of Photovoltaics, 6 (6), 1581-1586 (2016)

[4] B. Reagan, M. Berrill, K. Wernsing, C. Baumgarten, M. Woolston, and J. Rocca, “High-average-power, 100-Hz-repetition-rate, tabletop soft-x-ray lasers at sub-15-nm wavelengths,” Phys. Rev. A 89 053820 (2014)

[5] B. Reagan, W. Li, L. Urbanski, K. Wernsing, C. Salsbury, C. Baumgarten, M. Marconi, C. Menoni, and J. Rocca, "Hour-long continuous operation of a tabletop soft x-ray laser at 50-100 Hz repetition rate," Opt. Express 21, 28380-28386 (2013)

[6] B. Reagan, A. Curtis, K. Wernsing, F. Furch, B. Luther and J. Rocca, "Development of High Energy Diode-Pumped Thick-Disk Yb:YAG
Chirped-Pulse-Amplification Lasers," IEEE Journal of Quantum Electronics, 48(6), 827-835 (2012)

[7] B. Reagan, K. Wernsing, A. Curtis, F. Furch, B. Luther, D. Patel, C. Menoni, and J. Rocca, "Demonstration of a 100 Hz repetition rate gain-saturated diode-pumped table-top soft x-ray laser," Opt. Lett. 37, 3624-3626 (2012)

Program of Study: