Improved resolution in SPR and MCWG microscopy by combining images acquired with distinct mode propagation directions

Abstract

In high-resolution surface plasmon (SPR) imaging, lateral resolution is limited along the direction of plasmon propagation by the longitudinal decay length. Though SPR systems can achieve sub-micrometer resolution, the decay length causes a degradation in the images in the direction of plasmon propagation akin to a blurring artifact, with ringing along resonant to nonresonant transition edges. We present a method to significantly reduce this effect based on combining images of a sample acquired with distinct guided-mode propagation directions. As SPR is a special case of the class of optical structures known as metal-clad waveguides (MCWG) that are also affected by the decay length, this work is broadly applicable.

Nanoplasmonics-enhanced label-free imaging of endothelial cell monolayer integrity

“…However, SPRI is limited in spatial resolution due to the mode attenuation distance, which results in a directional blur in acquired images that was described by analytical models (Berger et al, 1994;Yeatman, 1996). Various approaches have been proposed to address this issue, but carry losses in sensitivity, temporal resolution or image contrast (Banville et al, 2015;Berguiga et al, 2016;de Bruijn et al, 1993;Giebel et al, 1999;Huang et al, 2007;Somekh et al, 2000;Wei et al, 2015). In previous works, we showed that nanostructured metal films are well suited for high resolution SPRI as they support a "hybrid" plasmonic mode, which is the result of a strong coupling between propagating (SPP) and localized (LSP) modes (Sarkar et al, 2015).…”

Quantitative Amplitude- and Phase- Contrast Plasmonic Microscopy with High Spatial Resolution

“…Another disadvantage of SPRM is the spatial resolution, which is limited by the micrometers-long propagating length of SPs on metal film (20,21). Including multiple-directions illumination could improve the spatial resolution, but complicate the optical systems and lower the imaging rate (22)(23)(24).…”

Monitoring individual cell-signaling activity using combined metal-clad waveguide and surface-enhanced fluorescence imaging

“…14 Note that spatial resolution in SPR and MCWG images is limited along the direction of light propagation by the finite mode attenuation length, rather than by diffraction. 17,18 Furthermore, there is an intrinsic trade-off between mode attenuation length and penetration depth into the sensing medium such that any increase in penetration depth comes at the expense of a commensurate decrease in imaging spatial resolution. Compared to SPR, MCWG offers the better compromise between spatial resolution and penetration depth.…”