Two-dimensional spatiotemporal focusing of femtosecond pulses and its applications in microscopy

Qiyuan Song, Aoi Nakamura, Kenichi Hirosawa, Keisuke Isobe, Katsumi Midorikawa, Fumihiko Kannari

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We demonstrate and theoretically analyze the two-dimensional spatiotemporal focusing of femtosecond pulses by utilizing a two-dimensional spectral disperser. Compared with spatiotemporal focusing with a diffraction grating, it can achieve widefield illumination with better sectioning ability for a multiphoton excitation process. By utilizing paraxial approximation, our analytical method improves the axial confinement ability and identifies that the free spectra range (FSR) of the two-dimensional spectral disperser affects the out-of-focus multiphoton excitation intensity due to the temporal self-imaging effect. Based on our numerical simulation, a FSR of 50 GHz is necessary to reduce the out-of-focus two-photon excitation by 2 orders of magnitude compared with that in a grating-based spatiotemporal focusing scheme for a 90-fs excitation laser pulse. We build a two-dimensional spatiotemporal focusing microscope using a virtually imaged phased array and achieve an axial resolution of 1.3 μm, which outperforms the resolution of conventional spatiotemporal focusing using a grating by a factor of 1.7, and demonstrate better image contrast inside a tissue-like phantom.

Original languageEnglish
Article number083701
JournalReview of Scientific Instruments
Volume86
Issue number8
DOIs
Publication statusPublished - 2015 Aug 1

Fingerprint

Ultrashort pulses
Microscopic examination
microscopy
pulses
excitation
gratings
phased arrays
image contrast
gratings (spectra)
Diffraction gratings
Optical resolving power
illumination
microscopes
Laser pulses
Microscopes
Photons
Lighting
photons
Tissue
approximation

ASJC Scopus subject areas

  • Instrumentation

Cite this

Two-dimensional spatiotemporal focusing of femtosecond pulses and its applications in microscopy. / Song, Qiyuan; Nakamura, Aoi; Hirosawa, Kenichi; Isobe, Keisuke; Midorikawa, Katsumi; Kannari, Fumihiko.

In: Review of Scientific Instruments, Vol. 86, No. 8, 083701, 01.08.2015.

Research output: Contribution to journalArticle

Song, Qiyuan ; Nakamura, Aoi ; Hirosawa, Kenichi ; Isobe, Keisuke ; Midorikawa, Katsumi ; Kannari, Fumihiko. / Two-dimensional spatiotemporal focusing of femtosecond pulses and its applications in microscopy. In: Review of Scientific Instruments. 2015 ; Vol. 86, No. 8.
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