Label-free CARS microscopy through a multimode fibre endoscope

Multimode fibres have recently been employed as high-resolution ultra-thin endoscopes, capable of imaging biological structures deep inside tissue in vivo. Here, we extend this technique to label-free non-linear microscopy with chemical contrast using coherent anti-Stokes Raman scattering (CARS) through a multimode fibre endoscope, which opens up new avenues for instant and in-situ diagnosis of potentially malignant tissue. We use a commercial 125 µm diameter, 0.29 NA GRIN fibre, and wavefront shaping on an SLM is used to create foci that are scanned behind the fibre facet across the sample. The chemical selectivity is demonstrated by imaging 2 µm polystyrene and 2.5 µm PMMA beads with per pixel integration time as low as 1 ms for epi-detection.Multimode fibres have recently been employed as high-resolution ultra-thin endoscopes, capable of imaging biological structures deep inside tissue in vivo. Here, we extend this technique to label-free non-linear microscopy with chemical contrast using coherent anti-Stokes Raman scattering (CARS) through a multimode fibre endoscope, which opens up new avenues for instant and in-situ diagnosis of potentially malignant tissue. We use a commercial 125 µm diameter, 0.29 NA GRIN fibre, and wavefront shaping on an SLM is used to create foci that are scanned behind the fibre facet across the sample. The chemical selectivity is demonstrated by imaging 2 µm polystyrene and 2.5 µm PMMA beads with per pixel integration time as low as 1 ms for epi-detection

Optical sorting and detection of sub-micron objects in a motional standing wave

An extended interference pattern close to surface may result in both a transmissive or evanescent surface fields for large area manipulation of trapped particles. The affinity of differing particle sizes to a moving standing wave light pattern allows us to hold and deliver them in a bi-directional manner and importantly demonstrate experimentally particle sorting in the sub-micron region. This is performed without the need of fluid flow (static sorting). Theoretical calculations experimentally confirm that certain sizes of colloidal particles thermally hop more easily between neighboring traps. A new generic method is also presented for particle position detection in an extended periodic light pattern and applied to characterization of optical traps and particle behaviorComment: 5 pages, 6 figures, Optical Trapping pape

Measurement of Intensity Profile in the Focal Region of Microscope Objective

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

SMV-2014-04: Micro-stereolithography writer

Contractual research is dealing with experimental development of apparatus for creating of microstructures with strongly focused laser beams. The microstructures are written into photoresist material by two-photon process. It is possible to write details in the range of hundreds of nanometers

SMV-2019-68: Implementation of advanced management and Implementation of optomechanical module

During the contract research work, a module for dynamic detection of vertical position of the substrate based on quadrature detection of astigmatic properties of laser diode beams and a module for advanced exposure control for writing in vector mode were created. Both modules were implemented in the apparatus and their function verifie

SMV-2022-45: Design of the Raman optical tweezers module

Design of the Raman optical tweezers module. The result of the research is a laser microscope adapter, which allows the introduction of a beam of laser radiation through an optical fiber into the optical system of a microscope. The micro-object is captured in the focused laser beam near its focal point. The captured micro-object remains fixed in the field of view of the microscope and can be moved relative to its surroundings by movement of the microscope stage. The microscope objective is used to display the field of view of the micro-objects and also focuses the laser beam

Optical tweezers and applications

Optical tweezers is very popular tool in many areas of science, namely in medicine, biology and physics. This micromanipulation tool is contactless, sterille and could be used as very sensitive force sensor

SMV-2022-44: Fabrication of optical tweezers for microrheology

Fabrication of optical tweezers for microrheology. The result of the research is a laser microscope adapter, which allows the introduction of a beam of laser radiation through an optical fiber into the optical system of a microscope. The micro-object is captured in the focused laser beam near its focal point. The captured micro-object remains fixed in the field of view of the microscope and can be moved relative to its surroundings by movement of the microscope stage. The microscope objective is used to display the field of view of the micro-objects and also focuses the laser beam