The Thirty Meter Telescope is a next-generation optical/infrared telescope to be constructed on Mauna Kea, Hawaii toward the end of this decade, as an international project. Its 30 m primary mirror consists of 492 off-axis aspheric segmented mirrors. High volume production of hundreds of segments has started in 2013 based on the contract between National Astronomical Observatory of Japan and Canon Inc.. This paper describes the achievements of the high volume production trials. The Stressed Mirror Figuring technique which is established by Keck Telescope engineers is arranged and adopted. To measure the segment surface figure, a novel stitching algorithm is evaluated by experiment. The integration procedure is checked with prototype segment.
The Thirty Meter Telescope (TMT) is a next-generation optical/infrared telescope to be constructed on Mauna Kea,
Hawaii toward the end of this decade, as an international project. Its 30 m primary mirror consists of 492 off-axis
aspheric segmented mirrors. This paper describes the progress of the test fabrication of an outermost mirror segment for
the TMT as a joint R&D program between National Astronomical Observatory and Canon. A zero-expansion glass
CLEARCERAM™ blank was polished by a computer-controlled small-tool polishing machine (CSSP, Canon) and its
surface shape was measured by a touch-probe measuring machine(A-Ruler, Canon). Residuals of lower Zernike terms of
the surface shape were 11 nmRMS, clearing the original specifications based on the structure function. There remains,
however, a need to fulfill latest revised specifications. Possible solutions to improve and achieve the new specifications
and a plan for revising the process for mass production are also described.
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