Analysis of sensitivity and resolution in plasmonic microscopes

Pechprasarn, Suejit (2012) Analysis of sensitivity and resolution in plasmonic microscopes. PhD thesis, University of Nottingham.

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Surface plasmons (SP) are guided electromagnetic wave propagating along the surface of metal. The properties of SP are affected by the material attached to the metallic surface so they can be used as a very sensitive sensor capable of detecting the deposition of subnanometric layers of dielectric. SP has been widely investigated for biosensor applications and the theory is well established.

Although SP sensors have been well studied, integrating the SP to a microscope is a relatively young field. Since the SPs are surface waves; microscopy techniques to optimise the SP microscope performance will require totally different techniques to non-surface wave microscopy.

This thesis develops a theoretical framework to understand different types of SP microscope setups through the rigorous diffraction theory. The framework analyses the diffraction process through rigorous wave coupled analysis (RCWA) and a software package processes the diffracted orders to recover the microscope response for a range of different systems. In this thesis I will investigate the non-interferometric SP microscope, interferometric SP microscope and confocal SP microscope. I will show that the non-interferometric system exhibits a trade-off between lateral resolution and sensitivity, where an image obtained with a good contrast will have low lateral resolution. In order to get around the trade-off, the interferometric system can be employed; however, the main challenge for the interferometric setup is its optical alignment. I will show that a confocal SP microscope, which has been developed as a part of this thesis, can simplify the complexity of the interferometric system and give similar measurement performance.

For the interferometric and confocal systems, the SP measurements are normally carried out through the interference signal, which is interference between a reference beam and the SP. I will suggest a method to extract SP propagation parameters from the interference signal by employing a spatial light modulator and also show that the SP propagation parameters do not only give us some insight to the SP effect for the interferometric system, but also gives us a new imaging mode to improve the resolution.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Somekh, M.G.
Keywords: Surface plasmon resonance, microscopy, resolution (Optics)
Subjects: Q Science > QC Physics > QC170 Atomic physics. Constitution and properties of matter
Faculties/Schools: UK Campuses > Faculty of Engineering > Department of Electrical and Electronic Engineering
Item ID: 13100
Depositing User: EP, Services
Date Deposited: 26 Mar 2013 12:06
Last Modified: 15 Dec 2017 05:33

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