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ref: -0 tags: 3D SHOT Alan Hillel Waller 2p photon holography date: 05-31-2019 22:19 gmt revision:4 [3] [2] [1] [0] [head]

PMID-29089483 Three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT).

  • P├ęgard NC1,2, Mardinly AR1, Oldenburg IA1, Sridharan S1, Waller L2, Adesnik H3,4
  • Combines computer-generated holography and temporal focusing for single-shot (no scanning) two-photon photo-activation of opsins.
  • The beam intensity profile determines the dimensions of the custom temporal focusing pattern (CTFP), while phase, a previously unused degree of freedom, is engineered to make 3D holograph and temporal focusing compatible.
  • "To ensure good diffraction efficiency of all spectral components by the SLM, we used a lens Lc to apply a small spherical phase pattern. The focal length was adjusted so that each spectral component of the pulse spans across the short axis of the SLM in the Fourier domain".
    • That is, they spatially and temporally defocus the pulse to better fill the SLM. The short axis of the SLM in this case is Y, per supplementary figure 2.
  • The image of the diffraction grating determines the plane of temporal focusing (with lenses L1 and L2); there is a secondary geometric focus due to Lc behind the temporal plane, which serves as an aberration.
  • The diffraction grating causes the temporal pattern to scan to produce a semi-spherical stimulated area ('disc').
  • Rather than creating a custom 3D holographic shape for each neuron, the SLM is after the diffraction grating -- it imposes phase and space modulation to the CTFP, effectively convolving it with a holograph of a cloud of points & hence replicating at each point.