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Optical Tweezers

Trapping of a large dinoflagellate
Movie (647KB)

Optical micromanipulation makes use of the fact that light carries energy and momentum, and sometimes even angular momentum. This allows one to build micro-tools of pure light which are able to catch, hold, move or stretch µm-size particles with pN forces.

We use Spatial Light Modulators (SLMs) to holographically shape optical traps. In the past we have realized dual-beam fiber optical traps, 2D or 3D arrays of trapping beams (operating in the Fourier or in the Fresnel regime), doughnut-shaped trapping beams which carry optical angular momentum and line traps of arbitrary shape

Recently we have developed a large-range mirror-trap, the Optical "Macro-Tweezers" system which is suitable to trap large and fast microorganisms. Adding an ultrasonic standing wave in a combined acoustic and optical trap we have a "best of both worlds scenario" with strong acoustic levitation and flexible and precisely controllable optical manipulation (see Topics below).

Projects

direct force measurement

Direct measurement of optical forces and torque with optical tweezers

overdrive_spot_switch_animated

Speeding up SLMs with overdrive

Optical "Macro-Tweezers"

Combined acoustic and optical trap

Holographic trapping patterns

Optical force measurements on pulmonary surfactant

Self-regularization in dual beam fiber traps

Moreover, we also use optical traps to hold specimens in place for quantitative phase microscopy.

Collaborations:

External links:

Optical Tweezers on Wikipedia

World Map of Optical Tweezers

Roberto di Leonardo's group in Rome