During 2009, Tinsley finished most of the Configuration 1 pre-cryo test Computer Controlled Optical Surfacing (CCOS)
operations on the James Webb Space Telescope primary mirror segments and in mid-2009 we began the Configuration 2
post-cryo test CCOS operations. After completing the grinding and polishing operations, including final figuring to a
cryo-null target, we delivered the finished Engineering Development Unit (EDU) to Ball Aerospace Technology
Corporation on 4 December 2009. Achieving fabrication and metrology conditions to meet the specifications for this off-axis
~1.5 m hexagonal point-to-point segmented mirror required special methods. Achieving repeatable and accurate
interferometric alignment of the off-axis aspherical mirror surface and stable thermal gradient control of the beryllium
substructure during tests required rigorous component and system-level validation. Final optical wavefront
measurements over the various spatial frequency ranges have demonstrated that all of the requirements are met. This
success has validated our processes of fabrication and metrology and allows us to proceed with the production of the 18
flight mirror segments. The first finished flight mirror, the Tertiary Mirror, was shipped to BATC on 24 February, 2010.
Performance of that mirror is reported here also.
JWST optical component in-process optical testing and cryogenic requirement compliance certification, verification &
validation is probably the most difficult metrology job of our generation in astronomical optics. But, the challenge has
been met: by the hard work of dozens of optical metrologists; the development and qualification of multiple custom test
setups; and several new inventions, including 4D PhaseCam and Leica Absolute Distance Meter. This paper summarizes
the metrology tools, test setups and processes used to characterize the JWST optical components.
The context, preparation, and facilitization of Tinsley to produce the 18 JWST primary mirror segments are described,
and an overview of the Project at Tinsley is presented. The mirror segments are aggressively lightweighted,
approximately hexagonal, and approximately 1.32m flat-to-flat. While the optical finishing approach is strongly seated
in Tinsley's Computer Controlled Optical Surfacing (CCOSTM) technology, extensions have been implemented to
address safe and efficient nearly simultaneous flow of the high value mirror segments through numerous cycles of
optical finishing, processing and metrology steps. JWST will operate at cryogenic temperatures, and Tinsley will do
final figuring from a "hit map" made during cryogenic testing at the NASA MSFC X-Ray Calibration Facility (XRCF).
A formal beryllium safety protocol has been established throughout. Extensive handling fixtures assure that the mirrors
are moved from station to station experiencing low accelerations. A rigorous qualification process is applied to each
new fixture, machine and instrument. Special problems of cryo figuring, and co-finishing the segments to stringent
specifications are described.