(a) EMCCD image of the photoluminescence from a single QD and reflected light by the alignment marks (metallic crosses), acquired by illuminating the sample simultaneously with both the red and near-infrared LEDs. (b) Orthogonal line cuts (horizontal=x axis, vertical=y axis) of the photoluminescence image, showing the profiles of the QD emission (solid symbols) and of the image of the alignment marks (open symbols) and their Gaussian fits (solid lines). (c) Histograms of the uncertainties of the QD and alignment mark positions and QD-alignment mark separations, measured from the Gaussian fits of line cuts from 45 images. The uncertainties represent one standard deviation values determined by a nonlinear least squares fit of the data. (d,e) Photoluminescence imaging through a solid-immersion lens. (d) Image of the photoluminescence from single QDs and reflected light from the alignment marks (metallic crosses), collected under the 630 nm/940 nm co-illumination scheme. (e) y axis line cuts from the photoluminescence image, showing the profiles of the QD emission (solid symbols) and reflected light from the alignment mark (open symbols). The solid lines are nonlinear least squares fits to Gaussians.