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).



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.


External links:

Optical Tweezers on Wikipedia

World Map of Optical Tweezers

Roberto di Leonardo's group in Rome