Improving surface plasmon resonance sensors with speckle image processing

This paper investigates digital image correlation approaches for assessing speckle patterns produced by surface plasmon resonance (SPR) imaging. An SPR sensor based on the Kretschmann setup comprising a gold-coated prism in a fixed angular position performs refractive index assessments in ethanol solutions. Subsequently, the acquisition system collects the reflected light and processes the speckle field images to evaluate the sensor's sensitivity, noise, and limit of detection. Based on three repetitions under similar conditions, the maximum resolution for the average intensity, zero-mean normalized cross-correlation, and the relative sum of square differences metrics are 4.90×10−4, 2.31×10−5, and 7.45×10−6 RIU, respectively, leading to an improved limit of detection without modifying the optical setup.