Optical metrology at the NSLS-II

Rapid progress in synchrotron optics performance places a high demand on optical characterization techniques used to validate surface parameters prior to installation of the X-ray optics. It is now necessary to characterize optical surface figure and slope errors and roughness on meter-long optics over spatial frequencies as short as 0.1 μm The new NSLS-II Optical Metrology Laboratory (OML) includes instruments for measuring: (1) long spatial frequency figure errors with a ZYGO MST Fizeau-type 4″ interferometer, capable of 0.1 nm sensitivity, (2) mid spatial frequencies with an upgraded ZYGO NewView 6300 white light interferometric microscope, capable of reaching 0.1 nm accuracy at a lateral resolution of 1 μm, (3) high frequency roughness with an AFM (Nanosurf AG) with linearity better than 0.2% over the 80 μm measurement area and sensitivity approaching 0.01 nm, and (4) slope errors with a long trace profiler currently under development that will be able to reach 50 nrad slope error accuracy. At present, the OML supports the NSLS-II R&D efforts and provides ongoing testing for NSLS optics. Future plans include the construction of a specialized metrology beamline for at-wavelength metrology, radiometry, in situ surface figuring, crystal optics characterization, and instrumentation development.