SBIR-STTR Award

High-accuracy metrology is vitally essential in manufacturing and optimally using ultra-high-quality free-form mirrors designed, for example, for space X-ray telescopes to manipulate X-ray light with nanometer-scale wavelengths. Due to the shorter wavelength, requirements to the surface figure (shape) and finish (roughness) of X-ray mirrors are many orders of magnitude more stringent than for visible-light optics. Metrology technology has not kept up with the advancement in fabrication technologies. The deficiencies in the metrology, rather than in the fabrication technologies, primarily limit the optical quality. We propose to develop a novel “turn-key” technology and methodology for high precision calibration and sophisticated data processing directed to advance the Cylindrical Wavefront Interferometry. Realizing the proposed goals will open a principally new avenue for fabrication and performance characterization of large-area strongly-aspherical grazing-incidence X-ray mirrors that are critical optical elements of the high-performing space X-ray telescopes and beamline systems the modern X-ray facilities. Potential NASA Applications (Limit 1500 characters, approximately 150 words): The technology will enable superior fabrication and performance characterization of large-area & strongly-aspherical grazing-incidence X-ray mirrors for X-ray telescopes by improving the metrology methodology. The capability for a full-dynamic-range ITF characterization of the metrology tool and data reconstruction to recover “true” optical surface has never been available before. The technology can be easily integrated with the existing metrology systems at NASA. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Using sophisticated full-spatial-frequency ITF characterization and beyond-resolution reconstruction of the metrology data, this product will bring existing metrological tools to their highest possible performance level; it will improve the optical quality of optics, reduce the cost of fabrication, and enable faster improvements in future designs of the instrumentation by equipment manufacturers. Duration: 6

High-accuracy metrology is vitally important in manufacturing and optimally using ultra-high-quality free-form mirrors designed, for example, for space X-ray telescopes to manipulate X-ray light with nanometer-scale wavelengths. Due to the shorter wavelength, requirements on the surface figure (shape) and finish (roughness) of X-ray mirrors are many orders of magnitude more stringent than for visible-light optics. The metrology integrated into X-ray mirror manufacturing must ensure the accuracy of optical surface fabrication on the sub-nanometer level over a large area (on the scale of a meter and even more) strongly aspherical optical elements with the sagittal ROC on the order of a meter and less, whereas the tangential ROC can reach a few hundred meters. The absence of the required metrology is the major limitation of modern technology used for the fabrication of X-ray mirrors. As an adage says, "If you can't measure it, you can't make it." Binary Pseudo Random Array test artifacts and accompanying data processing software offer unparalleled advantages to quantitatively characterize the instrument transfer function (ITF) of the metrology tools and enable data reconstruction to reveal the "true" surface. Previously, BPRA Based methodology has been validated with planar wavefront. In this Project, BPRA-based test artifacts & data processing methodology is adapted for the Cylindrical Wavefront Interferometry for inspection and calibration for mid-long range spatial frequencies. In Phase II, we will develop BPRA test artifacts with adjustable Radius of Curvature, and Computer Generate Holograms combined with BPRA for thorough calibration, and then data reconstruction based on the measured calibration data. The final product will be the BPRA test artifact with user-friendly and GI-controlled software. Anticipated

Benefits:
This product improves the integrated metrology process. The ability to assess the high accuracy and high-efficacy metrology is key to further improvement of the optical fabrication and lowering the cost of the X-ray optics. Both precision optics manufacturers and metrology tool makers are strongly interested in this technology. They all agree on the importance of metrology to further improve the product quality in optics and provide better metrology tools (including interferometers) to the customers.