Analysis of the Fluorescence Imaging of Surface Plasmon-coupled Emission Microscopy

Surface plasmon-coupled emission microscopy (SPCEM) that makes use of a thin layer of metal deposited on glass slides to efficiently excite fluorophore and to collect the emission light is a widely used imaging technique that has found a number of applications in areas such as biotechnology and biological measurements. SPCEM is a relatively new imaging technique that potentially promises better detection sensitivity and higher signal-to-noise ratio than conventional total internal reflection fluorescence (TIRF) imaging. However, recent theoretical studies suggest that the sensitivity of SPCEM is actually reduced due to the metal layer. We have designed a metal-dielectric multilayer film structure which consists of Ag-Si3N4 layers, and we have analyzed the transmission of two counter-propagation lights from the multilayer film by using the characteristic matrix method in the film optics. In this paper, optimization is utilized in the design of the multilayer film structure. And it is coated on the glass slides to improve the quality of microscopic imaging. We mainly use the optimization method to design the thickness of the metal layer and the dielectric layer. We analyze the transmission coefficient of two counter propagation lights from the multilayer film with different thickness and different number of layer. The refractive indexes with different number of the layer of multilayer film are also discussed.