Measuring chromatic aberration in imaging systems using plasmonic nano-particles

We demonstrate a novel method to measure chromatic aberrations of microscope objectives with metallic nano-particles using incoherent white light. Extinction spectra are recorded while scanning a single nano-particle through a lens's focal plane. We show a direct correlation between the focal wavelength and the longitudinal chromatic focal shift through analysis of the variations between scanned extinction spectra at each scan position and peak extinction over the entire scan. The method has been tested on achromat and apochromat objectives using aluminum nano-particles.