Dextrous use of a micromanipulation platform. An optical trap is teleoperated with an interface that allows force measurement feedback to be haptically experienced. A 3D reconstruction of the scene can also increase the user immersion. The haptic interface presented is the Omega™ from Force Dimension.
Comparison of the AFM and OT techniques for bilateral teleoperation purposes. Force-position characteristics with high adhesion effects for an AFM sensor (a) and the corresponding coupling scheme (b). Force-position characteristic for an OT sensor (c) and the corresponding coupling scheme (d). “z” is the displacement of the AFM support and “u” is the laser displacement. The useful domain of the characteristics have been colored on the graph. S disp and S force stand for the displacement and force scaling gains, respectively.
Comparison of two actuation techniques. (a) Conventional design for a single trap: the actuator is a motorized stage and the force sensor is a camera. (b) Modification of OT setup with a deflective actuator (galvanometers). Schematic representation of the impact of the two different actuation methods on the sample and the microscope camera for stage-based (c) and deflective methods (d).
Different actuators used in optical tweezers. (a) Motorized stage: MS; (b)Piezo-Motorized Lens: PML; (c) Piezo-Motorized mirror: PMM; (d) Galvanometers: G; (e) Acousto-optical deflector: AOD; (f) Spatial light modulator: SLM.
Position detection techniques for optical force measurement. (a) Interferometer using Wollaston prisms (W), a polarizer (P), and a quadrant photodiode (Q). (b) Technique using back focal plane (BFP) interferences of the condenser. (c) Imaging technique with quadrant or camera (C).
Backward and forward imaging principle. (a) The image is obtained in the back of the actuator on the laser path, (b) the image is obtained in the front of the actuator and stays aligned with the laser deflection. The image area can be reduced to decrease acquisition and processing times. The actuator, here galvanometers, should be reversible, i.e., reflective or transmissive in both ways.
Results with the forward imaging technique. (a) Operator during an exploration. The haptic interface is here a Novint Falcon®. (b) Haptic feedback rounds the corner of a silica cubic MEMS. Reproduced with permission from Pacoret et al., Optics Express 17, 10259 (2009). Copyright 2009 by Optical Society of America.
Dynamic image of two microspheres (3 μm and 11 μm) put into contact. Dots are the events sent by the asynchronous pixels in a 30 ms time windows. The color of the dots depends on the increment or decrement of light intensity on pixels.
Concept of advanced nimble microtools to explore cells using optical tweezers and haptic force feedback.
Comparison of three individual techniques of micromanipulation (based on molecular study applications 16 ).
Comparison of usual optical tweezers actuators according to the supplier's data-sheets. Abbreviations: MS: Motorized stage; PS: Piezoelectric stage; G: Galvanometer; PMM/PML: Mirror or lens mount on a piezoelectric scanner; AOD: Acousto-Optical Deflectors; SLM: Spatial Light Modulator; PI: Physik Instrument; CT: Cambridge Technology; QT: QUANTA TECH.
Comparison of high speed position detection methods. The acquisition and image processing are in frames per second (fps) for cameras and in refreshing rate (Hz) for others.
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