Optical and At Wavelength Metrology Team
Continue the Development of Next Generation of Metrology Tools and Techniques
This is essential to enable measurements of figure errors at sub 100-nrad levels. This targeted R&D strategic plan will be done by upgrading instrumentation in the existing NSLS-II optical metrology laboratory and efforts on the development of new instruments for slope errors measurements to reach 50 nrad slope error accuracy (NanoSurface Profiler and Software configurable optical test SCOTS ) and stitching interferometry capabilities for sub nm rms accuracy both on highly curved surfaces. These combine efforts towards the construction of new instruments with stitching capabilities using interferometer and Shack Hartmann and software configurable optical test (SCOTS) stations will be able to perform 2D mapping of the optical surfaces in order to feed a deterministic polishing process based on ion beam figuring.
At Wavelength Metrology / In Situ Alignment
In the same time, using the low emittance and the high stability of NSLS-II X-ray beam combined with extended possible beamline offered by large experimental hall may and should be used for metrology and optics characterization. The development of in situ at-wavelength metrology tools (metrology using directly the x-ray beam) for x-ray component characterization, alignment and beamline performance studies is a necessary complementary method of visible light metrology. Availability of adequate measurement tools and adjustments directly at the beamlines is crucial for thorough optimization of operational performance of individual beamline components and entire beamline systems. One of the major missions of in situ at-wavelength metrology is to provide the required instrumentation and measurement techniques to fulfill these requirements. In situ metrology is complementary to ex situ in the sense that it deals with optics preliminary tested, characterized, and adjusted at an optical metrology laboratory. However, in situ metrology allows fine mutual optimization of a sequence of beamline optical elements at the places and conditions where the optics are designed to operate. It overcomes the insensitivity of ex situ measurements to the imperfections of the input beam, tolerances of mounting of optics at the beamline, surface shape distortion due to x-ray heat absorption, as well as limited optical quality of the surrounding optical components. Moreover, in situ metrology has the potential to provide direct feedback for active (on-line) correction of the beam by using adaptive optics. At-wavelength wavefront characterization techniques will open up perspectives, for instance, in the in situ optimization of adaptive optics or correction of reflective optics and could also be used as an online setup permitting focusing optimization, for example, by assisting in the alignment of critical x-ray optical components or compensating for the astigmatism of an incoming beam or mechanical deformation due to heat load or mounting stress.
