NIST has developed a new method called Critical-Dimension Localization Microscopy (CDLM) that establishes SI-traceability for optical microscopy. This method allows for subnanometer localization accuracy over a submillimeter field, which is significantly more precise than current calibration methods.
The key innovation is using a reference artifact with two dimensional members that are subjected to critical-dimension metrology. By calibrating the optical field to the primary length, which is traceable to the International System of Units meter, CDLM enables the performance of critical-dimension localization microscopy.
NIST demonstrated the effectiveness of CDLM by fabricating arrays of sub-resolution apertures in an opaque metal film and characterizing a small field of the aperture array. The results showed that CDLM achieved subnanometer accuracy over submillimeter fields and greatly increased the throughput of such measurements compared to other forms of critical-dimension metrology.
This new method will enable CDLM for manufacturing metrology to perform quality control of reference materials with high throughput at low cost. It is the first method that allows a widefield optical microscope to achieve SI-traceable subnanometer localization accuracy across a submillimeter field.
Source: https://www.nist.gov/patents/apparatus-critical-dimension-localization-microscopy
Keywords: subnanometer, metrology, traceability, optical, microscopy
