Scattered light fluorescence microscopy in three dimensions

Author(s): Giulia Ghielmetti and Christof M. Aegerter

Abstract:

“Recently, we have proposed a method to image fluorescent structures behind turbid layers at diffraction limited resolution using wave-front shaping and the memory effect. However, this was limited to a raster scanning of the wave-front shaped focus to a two dimensional plane. In applications, it can however be of great importance to be able to scan a three dimensional volume. Here we show that this can be implemented in the same setup. This is achieved by the addition of a parabolic phase shift to the shaped wave-front. Via the memory effect, this phase shift leads to a shift of the interference based focus in the z-direction, thus opening the possibility of three dimensional imaging using scattered light fluorescence microscopy. Here, we show an example of such a three dimensional image of fluorescent nano-beads taken behind a turbid layer more than 10 mean free paths thick. Finally, we discuss the differences of the scanning in the z-direction with that in the x–y plane and the corresponding possibilities and limitations of the technique.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 20, Issue 4, pp. 3744-3752 (2012)
DOI: 10.1364/OE.20.003744

Pure two-dimensional polarization patterns for holographic recording

Author(s): Ulises Ruiz, Clementina Provenzano, Pasquale Pagliusi, and Gabriella Cipparrone

Abstract:

“Two-dimensional (2D) polarization patterns are achieved by the interference of two pairs of beams with perpendicular planes of incidence and orthogonal polarizations (i.e. linear or circular). In both cases, imposing a phase shift of π/2 between consecutive beams contains the amplitude modulation of the optical field in the superposition region and, thus, pure 2D polarization patterns are created. The recording of these interference fields in a polarization-sensitive material, namely an amorphous azopolymer, creates reconfigurable 2D periodic microstructures with peculiar diffraction properties.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 37, Issue 3, pp. 311-313 (2012)
DOI: 10.1364/OL.37.000311

Fabrication of three-dimensional electrospun microstructures using phase modulated femtosecond laser pulses

Author(s): Nathan J. Jenness, Yiquan Wu, Robert L. Clark.

Abstract:

“Electrospun polycaprolactone nanofibers were selectively ablated to form microstructures via the phase modulation of femtosecond laser beams. Ablation width (1–15 μm) and depth (15–110 μm) resolution were dependent upon the selection of pulse energy and microscope objective. Because phase modulation shapes light in a maskless fashion, desired templates were digitally created and physically transferred to electrospun mats within a matter of minutes. Several microarchitectures were formed in parallel by dividing pulse energy between multiple foci, substantially increasing throughput. The data presented herein demonstrates that phase-based laser ablation can be used to rapidly shape and tailor electrospun mats in three dimensions.”

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Publication: Materials Letters
Issue/Year: Materials Letters, Volume 66, Issue 1, 1 January 2012, Pages 360–363
DOI: 10.1016/j.matlet.2011.09.015