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We demonstrate the first use, to our knowledge, of a compact, diode-pumped, femtosecond fiber laser for third-harmonic generation (THG) microscopy. We discuss the utility of this technique, as well as the technical issues involved in using this compact source, and demonstrate the first use, to our knowledge, of imaging by THG backlighting.
We demonstrate a widefield multiphoton microscope and a temporally decorrelated, multifocal, multiphoton microscope that is based on a high-efficiency array of cascaded beamsplitters. Because these microscopes use ultrashort pulse excitation over large areas of the sample, they allow efficient use of the high-average power available from modern ultrashort… (More)
Ultrashort-pulse lasers are now commonly used for multiphoton microscopy, and optimizing the performance of such systems requires careful characterization of the pulses at the tight focus of the microscope objective. We solve this problem by use of a collinear geometry in frequency-resolved optical gating that uses type II second-harmonic generation and… (More)
We show that frequency-resolved optical gating combined with spectral interferometry yields an extremely sensitive and general method for temporal characterization of nearly arbitrarily weak ultrashort pulses even when the reference pulses is not transform limited. We experimentally demonstrate measurement of the full time-dependent intensity and phase of a… (More)
Frequency-resolved optical gating (FROG), a technique for measuring ultrashort laser pulses, involves producing a spectrogram of the pulse and then retrieving the pulse intensity and phase with an iterative algorithm. We study how several types of noise — multiplicative, additive, and quantization — affect pulse retrieval. We define a convergence criterion… (More)
We use the algorithmic method of generalized projections (GP's) to retrieve the intensity and phase of an ultrashort laser pulse from the experimental trace in frequency-resolved optical gating (FROG). Using simulations, we show that the use of GP's improves significantly the convergence properties of the algorithm over the basic FROG algorithm. In… (More)
We demonstrate a temporally decorrelated, multifocal multiphoton microscope. Using an etalon, we split the 800-nm light from either an ultrashort-pulsed Ti:Al (2)O (3) oscillator or a Ti:Al (2)O (3) regenerative amplifier into an array of beamlets that are delayed with respect to one another in time. The collimated beams overlap at slightly different input… (More)
We introduce a transient-grating beam geometry for frequency-resolved optical-gating measurements of ultrashort laser pulses and show that it offers significant advantages over currently used geometries. Background free and phase matched over a long interaction length, it is the most sensitive third-order pulse-measurement geometry. In addition, for pulses… (More)
We demonstrate what is to our knowledge the first frequency-resolved optical gating (FROG) technique to measure ultrashort pulses from an unamplified Ti:sapphire laser oscillator without direction-of-time ambiguity. This technique utilizes surface third-harmonic generation as the nonlinear-optical effect and, surprisingly, is the most sensitive third-order… (More)
A background-free, fringe-free form of frequency-resolved optical gating using the third-harmonic signal generated from a glass coverslip is used to characterize 100 fs pulses at the focus of a 0.65 NA objective.