Proximity projection grating structured illumination microscopy

Structured illumination has been employed in fluorescence microscopy to extend its lateral resolution. It has been demonstrated that a factor of 2 improvement can be achieved. In this thesis, we introduce a novel optical arrangement, which we call Proximity Projection Grating Structure Illumination Microscopy (PGSIM). Although the method is based on the original structured illumination, the present technique can further improve the lateral resolution of the microscope. The technique makes use of a fine grating held in close proximity to the sample, with a layer of high refractive index optical thin film sandwiched between the two. The fringe pattern thus projected onto the sample contains grating vectors substantially higher than those that are possible with the original structured illumination setup. The presence of these very high grating orders is the basis for the significant improvement in the system resolution. In this thesis, the principle behind the PGSIM will be explained. The optical system used to demonstrate the technique will be described, with particular attention paid towards the construction and alignment of the unit containing the fine grating. Experimental results will be presented to demonstrate the characteristics of the grating unit and the operation of the system. Further results obtained with the system applied to fine particles will be given, showing the resolution improvement of greater than a factor of 2 compared to a conventional optical microscope. The thesis also contains detailed analysis of the performance of the system. From this analysis, it is concluded that greater resolution improvement can be achieved by using appropriate material for the optical thin film.EThOS - Electronic Theses Online ServiceGBUnited Kingdo