National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Multiple Probe Photonic Force Microscopy
Jákl, Petr ; Šerý, Mojmír ; Zemánek, Pavel
Single beam optical trap (also known as optical tweezers) is created by a laser beam that is tightly focused by microscope objective with high numerical aperture. A dielectric particle in water medium is then dragged by optical forces to place of the highest optical intensity, i.e. to the laser beam focus. Photonic force microscopy (PFM) is a technique that utilizes optical tweezers for confining the local probe, usually a dielectric particle of a sub-micron diameter. I.e. PFM belongs to the of large family of scanning probe microscopy (SPM) techniques. We have used fluorescently labeled polymer sphere in order to conveniently measure the distance between the particle center and the focal point of the laser beam. To make the measurement more precise, we have measured two-photon-fluorescence, which is quickly decreasing with the probe-focus distance.
Measurement of Intensity Profile in the Focal Region of Microscope Objective
Šerý, Mojmír ; Ježek, Jan ; Jákl, Petr ; Jonáš, Alexandr ; Zemánek, Pavel ; Liška, M.
This work describes an experimental method for the measurement of the profile of the laser beam focused by an immersion microscope objective. The method makes use of the two-photon excited fluorescence emitted by a 200 nm dyed polystyrene bead fixed to the cover slip. A piezo driven stage is used for scanning of the bead through the focal volume of an infrared laser beam and the excited two-photon fluorescence is detected by a photomultiplier.

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