Comparison of optical resolutions of nanostructures on a Blu-ray disc when using a PS-20 microparticle with different magnifications of the microscope objective. (a) PS-20 microparticle (top) on a Blu-ray disc in the same region of interest but at a different Z value as the image taken with just the objective lens (bottom). The nanostructure is best focused through the microparticle when Z is 7.5 μm (top) and focused without the microparticle when Z is 0 μm (bottom) for the 5× microscope objective. (b) 10×, (c) 20×, (d) 50× objective imaging results respectively. (e) Line plot profile of the nanostructures captured at different focal distances (i) through the microparticle and (ii) without the microparticle using a 5× objective. (f) 10×, (g) 20×, (h) 50× objective imaging results, respectively.