Abstract: Transient phase detection, which measures the real component of the complex refractive index, is the complement to transient absorption detection, which measures the imaginary component of the complex refractive index. This work extends transient phase detection from spectroscopy to microscopy using a fast-galvanometer point-scanning setup and compares the trade-offs in transient phase versus transient absorption microscopy for the same pump and probe wavelengths. The realization of transient phase microscopy in conjunction with transient absorption microscopy opens a new door to measure the excited-state kinetics with phase-based or absorption-based techniques; depending on the sample and the wavelengths in use, transient phase detection may provide a signal improvement over transient absorption. Up until this point, transient phase microscopy has been a neglected technique in ultrafast pump-probe imaging applications. Additionally, this work evaluates a miniature piezoelectric actuator to replace galvanometers in a compact point-scanning microscope design. Sparsity limitations present in the design are addressed by the construction of a Fourier-projections based inpainting algorithm which could enable faster imaging acquisition in future applications.

Adviser: Jesse Wilson
Co-Adviser: N/A
Non-ECE Member: Nancy Levinger, CHEM
Member 3: Randy Bartels, ECE
Addional Members: Henry Adams, MATH

Publications:
Coleal, C. N., Hudson, W. A., & Wilson, J. W. (2023). Sparse Lissajous scanning reflectance confocal microscope with an adjustable field of view and fast iterative Fourier filtering reconstruction. Journal of the Optical Society of America A, 40(5), 942. https://doi.org/10.1364/JOSAA.484370

Program of Study:
ECE-503 Ultrafast Optics
ECE-604 Nonlinear Optics
ECE-504 Physical Optics
ECE-502 Advanced Fourier Optics
CHEM-571A Quantum Chemistry Foundations
ECE-518 Biophotonics
ECE-537 Biomedical Signal Processing
ECE-520 Optimization Methods-Control and Communication