Research Interests:
We present a simplified approach for imaging a linear diode bar laser for application as an optical stretcher within a microfluidic geometry. We have recently shown that these linear sources can be used to measure cell mechanical... more
We present a simplified approach for imaging a linear diode bar laser for application as an optical stretcher within a microfluidic geometry. We have recently shown that these linear sources can be used to measure cell mechanical properties; however, the source geometry creates imaging challenges. To minimize intensity losses and simplify implementation within microfluidic systems without the use of expensive objectives, we combine aspheric and cylindrical lenses to create a 1:1 image of the source at the stretcher focal plane and demonstrate effectiveness by measuring the deformation of human red blood cells and neutrophils.
Research Interests:
A Ti:Al(3)O(2) multipass chirped pulse amplification system is outfitted with a single-grating, simultaneous spatial and temporal focusing (SSTF) compressor platform. For the first time, this novel design has the ability to easily vary... more
A Ti:Al(3)O(2) multipass chirped pulse amplification system is outfitted with a single-grating, simultaneous spatial and temporal focusing (SSTF) compressor platform. For the first time, this novel design has the ability to easily vary the beam aspect ratio of an SSTF beam, and thus the degree of pulse-front tilt at focus, while maintaining a net zero-dispersion system. Accessible variation of pulse front tilt gives full spatiotemporal control over the intensity distribution at the focus and could lead to better understanding of effects such as nonreciprocal writing and SSTF-material interactions.
Research Interests:
Research Interests:
Characterization of the nonlinear refractive index of a material is important in order to fully understand the nonlinear propagation of femtosecond laser pulses. The most common method to obtaining the nonlinear refractive index is... more
Characterization of the nonlinear refractive index of a material is important in order to fully understand the nonlinear propagation of femtosecond laser pulses. The most common method to obtaining the nonlinear refractive index is Z-scan. However, since it averages over pulse duration and beam profile, Z-scan is not reliable when there is time- and intensity-dependence of the nonlinear response. The
Research Interests:
Research Interests:
We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less... more
We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband x-ray emission from an ultrashort pulse laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We amplified femtosecond pulses at repetition rates of as much as 7.2 kHz in a Ti:Al(2)O(3) regenerative amplifier pumped by a frequency-doubled Q-switched Nd:YLF laser. Energies of as much as 1 mJ at 1 kHz and 85 microJ at 7.2 kHz in a... more
We amplified femtosecond pulses at repetition rates of as much as 7.2 kHz in a Ti:Al(2)O(3) regenerative amplifier pumped by a frequency-doubled Q-switched Nd:YLF laser. Energies of as much as 1 mJ at 1 kHz and 85 microJ at 7.2 kHz in a 150-fs pulse have been obtained. This source was used to produce 1 W of femtosecond white light through spectral continuum generation.
Research Interests:
Research Interests: Applied Mathematics, Materials Science, Optics, Microscopy, Nonlinear Optics, and 11 moreFundamental Frequency, Refractive Index, Optical physics, Harmonic, Layered Structure, Paraxial Approximation, Material Properties, Third Harmonic Generation, Electrical And Electronic Engineering, Numerical Aperture, and Harmonic Generation
Research Interests:
Relatively small-scale laser-driven sources of short wavelength radiation covering a range from the extreme ultraviolet to the hard X-ray regime are now available. Because the duration of the X-ray pulses is comparable to, or shorter than... more
Relatively small-scale laser-driven sources of short wavelength radiation covering a range from the extreme ultraviolet to the hard X-ray regime are now available. Because the duration of the X-ray pulses is comparable to, or shorter than the laser pulse width, it is possible to carry out X-ray measurements with picosecond or femtosecond time resolution.
Research Interests:
Research Interests: Engineering, Materials Science, Optical Tweezers, Microfluidics, Flow Cytometry, and 15 moreLab On A Chip, Medicine, Cell separation, Lasers, Colloids, Optical Waveguide, Sorting, CHEMICAL SCIENCES, Particle Size, Optics and Photonics, Diode Laser, Sensitivity and Specificity, Equipment Design, Microfluidic Analytical Techniques, and Cell culture techniques
It is demonstrated that fluorescence lifetimes in the nanosecond and picosecond time‐scale range can be observed with the recently proposed double‐pulse fluorescence lifetime imaging technique (Müller et al., 1995, Double‐pulse... more
It is demonstrated that fluorescence lifetimes in the nanosecond and picosecond time‐scale range can be observed with the recently proposed double‐pulse fluorescence lifetime imaging technique (Müller et al., 1995, Double‐pulse fluorescence lifetime imaging in confocal microscopy. J. Microsc177, 171–179).A laser source with an optical parametric amplifier (OPA) system is used to obtain short pulse durations needed for high time resolution, wavelength tunability for selective excitation of specific fluorophores and high pulse energies to obtain (partial) saturation of the optical transition.It is shown that fluorescence lifetimes can be determined correctly also with nonuniform saturation conditions over the observation area.A correction scheme for the effect on the measurements of laser power fluctuations, which are inherently present in OPA systems, is presented. Measurements on bulk solutions of Rhodamine B and Rhodamine 6G in different solvents confirm the experimental feasibilit...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We have developed a 2 stage amplifier for ultrafast that will deliver 20mJ, 20fs laser pulses at a repetition rate of 1kHz. The novel power amplifier is pumped by up to 100W from 4 pump lasers, necessitating cryogenic cooling of the... more
We have developed a 2 stage amplifier for ultrafast that will deliver 20mJ, 20fs laser pulses at a repetition rate of 1kHz. The novel power amplifier is pumped by up to 100W from 4 pump lasers, necessitating cryogenic cooling of the amplifier crystal. In collaboration with ...
Research Interests:
SummaryTwo‐dimensional Fourier transform spectral interferometry is used to characterize the spatio‐temporal aberrations of a UV microscope objective. The spatial and temporal profiles of a 420 nm, 38 fs pulse at the focus of a 0.32 NA UV... more
SummaryTwo‐dimensional Fourier transform spectral interferometry is used to characterize the spatio‐temporal aberrations of a UV microscope objective. The spatial and temporal profiles of a 420 nm, 38 fs pulse at the focus of a 0.32 NA UV objective are then deduced using a wave propagation code incorporating the measured aberrations.