Practical limits for optical test of spatial resolution in advanced imaging devices

Decreasing pixel size, perfection of isolation, and improved dynamic range of advanced imaging devices requires an adequate optical arrangement to check crosstalk behavior within the pixel matrix. The Fraunhofer diffraction pattern; an inherent feature of any focused circular beam, leads to unintended direct illumination of the neighbors even if accurately centered. A Simple setup has been applied to determine the beam profile focused down to the subwavelength range. We propose to characterize the beam focusing for spatial resolution tests by the first zero to-zero width independent of peak intensity. We provide an estimate of minimum requirements to be fulfilled in order to test for a given crosstalk and demonstrate their importance on filled trench-isolated pixels.