In this paper a phase recovering scheme from the optical vortex microscope is presented. Laguerre-Gaussian beam with the vortex charge equal to one passes through the phase sample and then is detected at the observation plane. The sample modifies the internal structure of the vortex beam. The way of measuring such perturbation is presented. Numerical results are confirmed by the experiment.
We report the comprehensive application of double wavelength multifunctional optical tweezers. In the presented setup the measurement system is based on an inverted biological microscope. The system is equipped with two lasers of different wavelengths. The lasers’ beams, which generated optical traps, are controlled by galvanometer mirrors systems. Application of this setup has been presented in three examples. First one describes measurement of liposomes’ deformation, which is widely utilized in medical research. Secondly, the application of double wavelength multifunctional optical tweezers in precise control of micro-tools such as micro-dumbbells is presented. The third application of this system is the measurement of cell-to-cell adhesion forces, what is essential to understand the physical characteristics of living cells. In this paper we described preparation and process of samples measurement.
Magnetic fluids (ferrofluids) consist of magnetic nanoparticles (diameter ~10nm) which are dispersed in a liquid, often with the use of surfactants. They were first developed by NASA to address the unique requirements of moving liquid fuel in microgravity conditions. With a help of a holographic optical tweezers, interaction of magnetic nanoparticles with strongly focused laser beam was observed. When the light intensity was high enough, magnetic nanoparticles were removed from the beam center and they formed a dark ring. Creation process lasts less than 330μs and cannot be observed precisely even with ultrafast camera. Such rings exist when the laser beam is affecting the sample and disappear (with a lifespan of 10’th second range) after the laser is switched off. Moreover, when several rings are created simultaneously, complex interactions between them can be observed. In this work, the results of our experiments will be presented with hypotheses about the physical background of such a behavior.