Publications by authors named "J Omachi"

Frequency recognition algorithm for multiple exposures (FRAME) is a high-speed videography technique that exposes a dynamic object to time-varying structured illumination (SI) and captures two-dimensional transients in a single shot. Conventional FRAME requires light splitting to increase the number of frames per shot, thereby resulting in optical loss and a limited number of frames per shot. Here, we propose and demonstrate a novel FRAME method which overcomes these problems by utilizing an interferometer to generate a time-varying SI without light splitting.

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Nonlinear optical microscopy allows for rapid high-resolution microscopy with image contrast generated from the intrinsic properties of the sample. Established modalities, such as multiphoton excited fluorescence and second/third-harmonic generation, can be combined with other nonlinear techniques, such as coherent Raman spectroscopy, which typically allow chemical imaging of a single resonant vibrational mode of a sample. Here, we utilize a single ultrafast laser source to obtain broadband coherent Raman spectra on a microscope, together with other nonlinear microscopy approaches on the same instrument.

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We report a broadband refractive index measurement method based on a higher harmonic generation tabletop coherent extreme ultraviolet source. We measured the complex refractive index of a sample material by measuring the interference pattern produced by a bare double slit and comparing this with the pattern produced by another double slit with one slit covered by the sample material. We validated the method by measuring the complex refractive index of aluminum in the photon energy range of 63-78 eV using a neon gas jet.

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Ultrahigh-repetition-rate (1.1 GHz), deep-ultraviolet coherent light at 208.8 nm is generated by applying an external Fabry-Pérot cavity for repetition-rate multiplication to the fourth harmonics of a 10-ps, mode-locked Ti:sapphire laser.

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We demonstrate ultra-broadband Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy spanning over 3,000 cm with a rapid-scan Michelson interferometer at a scan rate of 24,000 spectra/s. Using sub-10-fs optical pulses from a mode-locked laser, we measure broad CARS spectrum covering both the fingerprint region (500-1,800 cm) and the C-H, N-H, O-H stretching region (2,700-3,600 cm). To the best of our knowledge, this is the first demonstration of coherent Raman scattering spectroscopy covering over 3,000 cm at a scan rate of more than 10,000 spectra/s.

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