Linear versus Non Linear Super Resolved Microscopy

Classically, microscopes have a fundamental resolution limit due to diffraction. Super resolution techniques may overcome this limit by using a priori information about the input object. In this chapter we discuss the usage of time multiplexing based super resolution technique while comparing between two options of realization one through linear optics and one through non linear one. The linear optics technique is based upon injecting randomly space and time-varied gold nano-particles close to the inspected object. This flow of particles is used as the encoding pattern and since the size of the particles is smaller than the resolution limit of the microscope, proper time multiplexing algorithm allows obtaining a decoding i.e. generation of synthetic aperture with higher NA leading to the recovery of the spatial high resolution features. In the non linear optics technique similar time multiplexing super resolved method is applied. This time the randomly space and time varying encoding structure having high resolution features is obtained due to various nonlinear fluorescence emission effects. The chapter overview various non linear relevant effects and examines the minimal power that is required from the excitation light in order to obtain super resolution. The results show that it is almost impossible to get the nonlinear fluorescence effect without getting being limited by the fluorescence quenching, bleaching and saturation phenomena.