In this work, we implement an optical resonant sensor with high throughput capabilities to act as chemical or biosensor. We optimized the diffraction grating structures by FDTD simulations. Based on this study, we produced dielectric diffractive gratings in 1 cm2 areas by laser interference lithography (LIL) and interrogated them with white light. The reflected single wavelength shifted with changes of the external medium's refractive index (RI), resolving variations of 7.3 × 10-5 refractive index units (RIU). To exploit the broad active areas fabricated, we developed a custom instrument to acquire spatial maps of the resonance. We called the technique broad area resonance scan (BARS) and used it to characterize the geometric and material uniformity of the surfaces. We suggest this as an in situ practice to characterize photonic crystals and also as a method to scan highly parallelized analysis on a single chip in real time. In addition to a refractometric label-free application, we demonstrated a fluorescent-based measurement with the same readout and found state of the art sensitivities. Thus, the multimethod platform presented is able to double prove an assay with a single experiment in addition to its ability to screen large numbers of interactions using low volume of reagents.