Hybrid Interferometric and Deflectometric Stitching and Data Reconstruction for X-ray Mirrors

Precision optics for high-power X-ray sources are required to propel a wide range of quantum and materials science investigations in support of new technology development and biomedical research. They are challenging to make and US technology currently lags behind international competitors. What is needed is improved methodology to measure the optical surface during the manufacturing process. The new approach to in-process mirror metrology combines measurements using smart fiducials in overlapping sub-apertures defined by a pseudo-random pattern. Separately, a deflectometry system looking at the mirror surface at an oblique angle provides a “framework” at mid to high spatial frequencies on which the interferometry data, at higher resolution and higher precision, may be hung. A newly developed method will precisely stitch together the measurements. A second new method will remove the instrument transfer function from the data to further enhance the measurement accuracy. In Phase I, the method will be demonstrated using an existing interferometer on mirror samples of order 100-200 mm. In parallel, the software tools will be developed to implement the fusion of interferometer and deflectometer data, sub-aperture stitching, and removal of the instrument transfer function. An intuitive and interactive user interface will be developed to display the surface maps, compute statistical metrics, and show synthetic X-ray images for a given beam profile computed from the measured mirror surface. The new technology will enable the commercial manufacture of grazing incidence X-ray mirrors of superior quality. The immediate applications of these mirrors are in high-power X-ray laser beam lines, where they will enable higher power density on the target. In turn, this will support a broad range of research efforts including, for example, elucidation of protein and macromolecular crystal structure on ever smaller scales, investigation of materials properties in the development of quantum computing hardware, and time-resolved structural and dynamic behavior of polymeric compounds of interest in advanced manufacturing processes such as 3D printing. Beyond X-ray systems, the new metrology tools will also serve to improve the quality of optics used in semiconductor lithography machines that use extreme ultraviolet light. These engines write the microscopic electronic components on silicon integrated circuits that are ubiquitous in computers and smart systems the world over. Moving further down the electromagnetic spectrum, the technology will also reduce the fabrication time for precision mirrors at visible wavelengths, used in optical systems from astronomical telescopes to space-based sensors, because of the wide dynamic range of the method compared to existing tools. This allows precise measurements of surface figuring requirements to be made during the manufacturing process which may then be completed in fewer steps.