We welcome Dr. Jeff Squier from the Colorado School of Mines, where he is a Professor in the Department of Physics.
Advances in Linear and Nonlinear Spatial Frequency Modulation Imaging
Abstract: In this talk we present multiple new paradigms in single element detection, two-dimensional, linear and nonlinear spatial frequency modulated imaging (SPIFI) platforms. SPIFI is one of the first single element detection methods to achieve enhanced resolution across imaging modalities. First, in order to optimize the nonlinear imaging conditions across the field-of-view, a compact, efficient dispersion compensation system well suited for these applications is presented. This system can be seamlessly deployed in line between the femtosecond laser source and the multiphoton microscope. A novel aspect of this system is that it can also be used to retrieve the spectral phase and amplitude of the femtosecond laser pulse at the focus (image plane) of the microscope objective. This enables rigorous characterization of the focal intensities at all times to ensure optimized imaging conditions and a quantitative understanding of exposure conditions which can be especially important when imaging delicate biological systems. Notably it is compatible with simultaneous spatial and temporal focusing (SSTF) methods as well. We will present a series of measurements for different ultrafast laser sources and nonlinear imaging platforms demonstrating the utility of this new pulse characterization and compensation system. Next, we will present novel extensions of the SPIFI method to two-dimensional image acquisition. The first method enables two-dimensional random-access imaging, while the second method provides enhanced resolution in multiple directions across the field-of-view in SPIFI for the first time.
Bio: Jeff Squier received his PhD in Optics from the University of Rochester in 1992 and his advisor was Professor Gérard Mourou (the 2018 Nobel Laureate in Physics). While a graduate student, he developed the first solid-state, femtosecond chirped pulse amplification systems. These systems broke the one Watt average power barrier (10 mW was the previous state-of-the-art!). He used these lasers to perform some of the earliest work in femtosecond micromachining, multiphoton imaging, femtosecond laser eye surgery, and filimentation. Indeed, collaborating with G.J. Brakenhoff, he developed the first real-time two-photon excitation fluorescence imaging system. He joined the Physics department at Colorado School of Mines in 2002, where his research focuses on novel laser development, pulse shaping and characterization, multiphoton imaging, laser trapping, and filimentation studies. He served as Department Head of Physics(2014-2017) where he collaborated on the design of the CoorsTek Center for Applied Science and Engineering, the new home for the Physics Department. His group, collaborating with Professor Randy Bartels (Colorado State University), has most recently developed a single element detection, extended excitation source for linear and nonlinear imaging that exhibits enhanced resolution cross all imaging modalities. He is a Fellow of the Optical Society of America and the 2014 recipient of the SPIE. Harold E. Edgerton Award.