Holographic optical tweezers

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Holographic optical tweezers

Principal investigator : Serge Monneret

Holographic optical tweezers (HOT) allow the trapping beam to be split up into more than one trap at different positions, by means of a diffractive optical element (DOE) which is generally a hologram. Most holographic setups place the traps in the Fourier-plane of the DOE implying that a linear phase at the DOE results in a lateral displacement of the optical trap. Originally demonstrated with a commercial diffractive 4x4 square array generator, HOT have since then been implemented with a computer-addressed spatial light modulator as the DOE, allowing diffractive pattern to be quickly replaced in a cartoon fashion, and dynamically reconfigure the resulting spatial distribution of traps. HOT use holograms that are almost always phase holograms, also called kinoforms, as intensity holograms would decrease the power in the trapping beam.

Figure 1 : examples of holographic traps, where the trapped particles are silica beads of diameter 2.3 micrometers.

Figure 2 : trapping of two living cells, with simultaneous fluorescence imaging.

During year 2008, we made a copy of the HOT setup, which is now settled in one of our partner lab (CIML), where biologists from the group of D. Marguet and HT He are using it to study cell membrane dynamics and /or realize cell-cell contacts with controlled parameters.

People involved

  • Serge Monneret
  • Didier Marguet (CIML)
  • Vincent Rouger (CIML)