Study on the Despeckle Methods in Angular Surface Plasmon Resonance Imaging Sensors

Abstract

The speckle effects caused by the coherence of the laser light sources have restricted the performances of angular surface plasmon resonance (SPR) imaging sensors, which are widely used due to their wide linear rage, high refractive index (RI) resolution, and simple structure. In this work, we experimentally studied the influence of two common despeckle methods (laser with a rotating diffuser and an incoherent light-emitting diodes (LED) light source) on the RI resolution of an angular SPR imaging sensor. We found that the LED light source with a band-pass filter could not only eliminate the speckle effect completely but also provide better RI resolution than the other despeckle method. This low-cost specklefree method has the potential to promote the development and the industrialization of angular SPR imaging sensors.

Integration of Faradaic electrochemical impedance spectroscopy into a scalable surface plasmon biosensor for in tandem detection

“…A 18mW 780nm centered LED (Thorlabs LED780E), bandpassed to 3nm spectral FWHM (Semrock Line filter 785nm) is used as the source to excite surface plasmons on the grating. An LED was chosen over a diode laser in order to remove coherent speckle interference, an artifact of coherence that is severely intolerant of system instability and detrimental to sensitivity [19]. The diverging beam is collimated, passed through a polarizer, and focused by a cylindrical lens onto the grating, through the mounted PDMS.…”