Surface Roughness Techniques for Measuring Super-Smooth Optics
Thursday, September 28, 2023, 1:00 PM - 1:30 PM

For UV, EUV, and X-ray wavelength applications, optics must be extremely smooth to avoid scattering, which affects image quality, signal-to-noise, and other critical optical performance properties. The typically high incident energy can also degrade optics quickly.  In order to ensure sub-nanometer level smoothness for optical performance, a reliable, reproducible measurement method is critical.  But, while newer manufacturing techniques have enabled production of supersmooth optics, the metrology to accurately measure these surfaces has lagged behind.

This presentation will discuss some of the challenges of measuring sub-nanometer level surface roughness and compare the different measurement techniques for these types of measurements available today.  It will also introduce a novel vibration-insensitive measurement technique that has demonstrated advanced capabilities in measuring super-smooth optics, especially in noisy environments.

Last, the talk will discuss different factors to consider while choosing a technology to measure super smooth optics, such as spatial requirements, repeatability, size of the optic, and environmental considerations such as vibration, turbulence, and automation requirements.