An incident signal illuminates an SPR sensor over a wavelength range. Intensity of a reflected signal from the SPR sensor is detected with wavelength discrimination imposed on the incident signal or the reflected signal. The wavelength discrimination is imposed at a predesignated tuning rate within the wavelength range. The detected intensity is then sampled at a sampling rate and an intensity profile associated with the SPR sensor is established from the sampling with a wavelength resolution determined by the tuning rate and the sampling rate.