The National Institute of Standards and Technology (NIST) has developed a new calibration method with the goal of improving precision and accuracy when viewing the nanometer-scale. The reference materials used in their publication were dependent on nanometer-scale fabrication techniques. Additionally, they used ion milling and electron beams to create pinhole apertures in a film of platinum on a glass slide.
The aperture arrays would significantly increase the optical microscope's ability to locate the positions of molecules and nanoparticles.