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Luca Poletto - One of the best experts on this subject based on the ideXlab platform.

  • Single-Grating Monochromators for Extreme-Ultraviolet Ultrashort Pulses
    Applied Sciences, 2012
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    A Single-Grating monochromator can be used for the spectral selection of ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. Two configurations are compared: the classical-diffraction mount (CDM) and the off-plane mount (OPM). The advantages and drawbacks of both configurations are presented. The two geometries can be joined in a new and innovative design of a monochromator with two interchangeable diffracting stages both used at grazing incidence, one with the Gratings in the CDM and the other in the OPM. The use of two stages gives great flexibility: the OPM stage is used for sub-50 fs time response and low spectral resolution and the CDM stage for 100-200 fs time response and high spectral resolution. The design overcomes the limits of the two Single configurations, giving on the same instrument either ultrafast response with low spectral resolution or slower response with higher resolution.

  • Single-Grating monochromator for extreme-ultraviolet ultrashort pulses
    Optics Express, 2011
    Co-Authors: Fabio Frassetto, Cephise Cacho, C.a. Froud, I C Edmund Turcu, Paolo Villoresi, W. A. Bryan, Emma Springate, Luca Poletto
    Abstract:

    Extreme-ultraviolet high-order-harmonic pulses with 1.6·10(7) photons/pulse at 32.5 eV have been separated from multiple harmonic orders by a time-preserving monochromator using a Single Grating in the off-plane mount. This Grating geometry gives minimum temporal broadening and high efficiency. The pulse duration of the monochromatized harmonic pulses has been measured to be in the range 20 to 30 fs when the harmonic process is driven by an intense 30 fs near-infrared pulse. The harmonic photon energy is tunable between 12 and 120 eV. The instrument is used in the monochromatized branch of the Artemis beamline at the Central Laser Facility (UK) for applications in ultrafast electron spectroscopy.

  • Design of time-preserving Grating monochromators for ultrashort extreme-ultraviolet pulses
    2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE EQEC), 2011
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    The design of Grating monochromators to increase the spectral purity of extreme-ultraviolet (XUV) ultrashort femtosecond sources, such as high-order laser harmonics (HHs) or free-electron lasers, is discussed. The use of Gratings for the spectral selection intrinsically introduces a temporal broadening of the output pulse because of diffraction. In the case of a Single-Grating monochromator, once the resolution λ/Δλ at the output has been defined, the minimum number of grooves that have to be involved in the diffraction to support such a resolution is N min = λ/Δλ. It can be shown that the corresponding time broadening is close to the Fourier limit for a given bandwidth Δλ [1]. Therefore the Single-Grating design can be adopted for ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. A Grating monochromator is defined to be time-preserving if the temporal duration at the output is close to the Fourier limit for a given spectral bandwidth.

  • Time-preserving Grating monochromators for ultrafast extreme-ultraviolet pulses
    Applied Optics, 2010
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    We analyze the time response of Single-Grating monochromators for application to extreme-ultraviolet ultrashort pulses. It is shown that time-preserving monochromators can be realized in a Single-Grating configuration if the number of illuminated grooves is the minimum for a given resolution and the Grating time response is close to the Fourier limit for such a resolution. Two different Grating configurations are compared: the classical diffraction mount (CDM) and the off-plane mount (OPM). We shown that the CDM is preferred for Single-Grating monochromators with relatively long time responses, i.e., 100-200 fs, while the OPM is suitable for ultrashort time responses in the 10-50 fs range to realize femtosecond time-preserving monochromators.

Fabio Frassetto - One of the best experts on this subject based on the ideXlab platform.

  • Single-Grating Monochromators for Extreme-Ultraviolet Ultrashort Pulses
    Applied Sciences, 2012
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    A Single-Grating monochromator can be used for the spectral selection of ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. Two configurations are compared: the classical-diffraction mount (CDM) and the off-plane mount (OPM). The advantages and drawbacks of both configurations are presented. The two geometries can be joined in a new and innovative design of a monochromator with two interchangeable diffracting stages both used at grazing incidence, one with the Gratings in the CDM and the other in the OPM. The use of two stages gives great flexibility: the OPM stage is used for sub-50 fs time response and low spectral resolution and the CDM stage for 100-200 fs time response and high spectral resolution. The design overcomes the limits of the two Single configurations, giving on the same instrument either ultrafast response with low spectral resolution or slower response with higher resolution.

  • Single-Grating monochromator for extreme-ultraviolet ultrashort pulses
    Optics Express, 2011
    Co-Authors: Fabio Frassetto, Cephise Cacho, C.a. Froud, I C Edmund Turcu, Paolo Villoresi, W. A. Bryan, Emma Springate, Luca Poletto
    Abstract:

    Extreme-ultraviolet high-order-harmonic pulses with 1.6·10(7) photons/pulse at 32.5 eV have been separated from multiple harmonic orders by a time-preserving monochromator using a Single Grating in the off-plane mount. This Grating geometry gives minimum temporal broadening and high efficiency. The pulse duration of the monochromatized harmonic pulses has been measured to be in the range 20 to 30 fs when the harmonic process is driven by an intense 30 fs near-infrared pulse. The harmonic photon energy is tunable between 12 and 120 eV. The instrument is used in the monochromatized branch of the Artemis beamline at the Central Laser Facility (UK) for applications in ultrafast electron spectroscopy.

  • Design of time-preserving Grating monochromators for ultrashort extreme-ultraviolet pulses
    2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE EQEC), 2011
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    The design of Grating monochromators to increase the spectral purity of extreme-ultraviolet (XUV) ultrashort femtosecond sources, such as high-order laser harmonics (HHs) or free-electron lasers, is discussed. The use of Gratings for the spectral selection intrinsically introduces a temporal broadening of the output pulse because of diffraction. In the case of a Single-Grating monochromator, once the resolution λ/Δλ at the output has been defined, the minimum number of grooves that have to be involved in the diffraction to support such a resolution is N min = λ/Δλ. It can be shown that the corresponding time broadening is close to the Fourier limit for a given bandwidth Δλ [1]. Therefore the Single-Grating design can be adopted for ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. A Grating monochromator is defined to be time-preserving if the temporal duration at the output is close to the Fourier limit for a given spectral bandwidth.

  • Time-preserving Grating monochromators for ultrafast extreme-ultraviolet pulses
    Applied Optics, 2010
    Co-Authors: Luca Poletto, Fabio Frassetto
    Abstract:

    We analyze the time response of Single-Grating monochromators for application to extreme-ultraviolet ultrashort pulses. It is shown that time-preserving monochromators can be realized in a Single-Grating configuration if the number of illuminated grooves is the minimum for a given resolution and the Grating time response is close to the Fourier limit for such a resolution. Two different Grating configurations are compared: the classical diffraction mount (CDM) and the off-plane mount (OPM). We shown that the CDM is preferred for Single-Grating monochromators with relatively long time responses, i.e., 100-200 fs, while the OPM is suitable for ultrashort time responses in the 10-50 fs range to realize femtosecond time-preserving monochromators.

Ding Zhao - One of the best experts on this subject based on the ideXlab platform.

Wenqiu Xie - One of the best experts on this subject based on the ideXlab platform.

Kazuto Yamauchi - One of the best experts on this subject based on the ideXlab platform.

  • X-Ray Single-Grating Interferometry for Wavefront Measurement and Correction of Hard X-Ray Nanofocusing Mirrors.
    Sensors (Basel Switzerland), 2020
    Co-Authors: Jumpei Yamada, Takato Inoue, Satoshi Matsuyama, Kazuto Yamauchi, Nami Nakamura, Takashi Kameshima, Makina Yabashi
    Abstract:

    X-ray Single-Grating interferometry was applied to conduct accurate wavefront corrections for hard X-ray nanofocusing mirrors. Systematic errors in the interferometer, originating from a Grating, a detector, and alignment errors of the components, were carefully examined. Based on the measured wavefront errors, the mirror shapes were directly corrected using a differential deposition technique. The corrected X-ray focusing mirrors with a numerical aperture of 0.01 attained two-dimensionally diffraction-limited performance. The results of the correction indicate that the uncertainty of the wavefront measurement was less than λ/72 in root-mean-square value.

  • Wavefront measurement for a hard-X-ray nanobeam using Single-Grating interferometry.
    Optics Express, 2012
    Co-Authors: Satoshi Matsuyama, Hikaru Yokoyama, Ryosuke Fukui, Yoshiki Kohmura, Kenji Tamasaku, Makina Yabashi, Wataru Yashiro, Atsushi Momose, Tetsuya Ishikawa, Kazuto Yamauchi
    Abstract:

    Wavefront measurement for a hard-X-ray nanobeam using Single-Grating interferometry based on the Talbot effect and the Fourier transform method was demonstrated in the 1-km-long beamline of SPring-8. 10 keV X-rays were one-dimensionally focused down to 32 nm using a total-reflection elliptical mirror. An intentionally distorted wavefront was generated using a deformable mirror placed just upstream of the focusing mirror. The wavefront measured by interferometry was cross-checked with the phase retrieval method using intensity profiles around the beam waist. Comparison of the obtained wavefront errors revealed that they are in good agreement with each other and with the wavefront error estimated from the shape of the deformable mirror at a ~0.5 rad level.