This Superflat task aims to develop new metrology methods and measurement protocols suitable for production environments.
Task strategy:
Many of the metrology tools used within the RI community for the quality control of reflective optics are ill adapted for use in an industrial process for X-ray mirror/substrate production.
Beyond the prototype stage, viable high performance manufacturing processes will require the necessary metrology tools to be at the production site to allow use in an iterative scheme of measurement followed by corrective figuring stages, where over ten cycles may be required. The metrology tool must also be capable of providing height (or slope) information over the entire surface meaning that instruments capable of providing only line profiles are ill-adapted.
All of the task participants operate state of the art optical metrology facilities. This task will build upon their expertise and resources to develop or extend the capabilities of metrology tools which can satisfy the constraints of the manufacturing processes.
The measurement protocols will permit validation of the prototypes produced in the PCP activity but also extend the state of the art in perspective of more complex curved surface figures.
The demands of reliable measurement of surface topography at the sub-nm level are such that it is important to repeat measurements across several independent sites to ensure overall consistency. The work will explore several alternative non-contact, optical inspection technologies including micro-stitching interferometry (SOLEIL, ESRF, DIAMOND), stitching Fizeau interferometry (ALBA, ESRF, SOLEIL, DIAMOND) with performance validation with more established line profile deflectometry techniques (ALBA, HZB, DIAMOND, ESRF, SOLEIL).
In addition to guaranteeing the data reliability, the use of complementary technologies will also probe the surface heights at different length scales. Efforts will be made to improve the flatness calibrations of the instruments with traceability to national flatness standards.