We have set up two distinct Optical Fiber Tweezers, one dedicated to the spectroscopic characterization of nanoparticles trapped in suspension (Tweezers I) and the second one optimized for optical trapping of air-born particles, but also working in suspension (Tweezers II). The main characteristics of the two set-ups are summarized in the table below. Both tweezers are working at a wavelength of 808 nm, outside of the main water absorption bands. They can be used in single and dual fiber configurations. The optical fibers are mounted on piezoelectric xyz translation stages with sub-nanometer precision. Particle trapping is observed perpendicular to the optical fibers, using a long working distance microscope objective and a scientific CMOS camera.
Tweezers I |
Tweezers II |
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intensity control |
(no alignment) |
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- resolution - max. frame rate |
100 nm/pixel 330 fps |
130 nm/pixel 1000 fps |
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decay time |
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Different pump lasers are available to observe and/or characterize Cr3+, Er3+/Yb3+, and Eu3+-doped particles. Tweezers I allows us to record the trapped particle emission in three orthogonal directions for spectroscopic or emission decay time measurements. On the other hand, Tweezers II includes a three stage trapping chamber together with a nebulizer to inject air-born particles into the trapping volume.
The trap stiffness is calculated from trapping videos using Power Spectrum Analysis and Boltzmann statistics in the framework of the equipartition theorem. The corresponding programs have been developed in the Scilab environment.
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Schema of Optical Fiber Tweezers I. |
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Schema of the spectroscopic configuration of Tweezers I. |
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Schema of Optical Fiber Tweezers II. |
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Optical Fiber Tweezers I. |
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Optical Fiber Tweezers II. |
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