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<title>Fabrication of SUBARU primary mirror blank</title>

1994; SPIE; Volume: 2199; Linguagem: Inglês

10.1117/12.176263

1996-756X

Richard Smith, Mary J. Edwards, Donald B. Kloeber,

Laser and Thermal Forming Techniques

Coming Incorporated was awarded a contract in August 1991 by Mitsubishi Electric Corporation (Melco), Tokyo, Japan to fabricate an 8.31 meter diameter ULETMpnmary mirror blank for the Subaru (Japan National Large Telescope) Project. The project is sponsored by the National Astronomical Observatory of Japan. This paper reviews the progress and status of the project to date. Coming's history in producing mirror blanks for astronomy spans nearly 60 years beginning in 1936 with the manufacture of the 200 inch Hale Telescope blank made of Coming's borosilicate glass. Since that time, among the many mirror blanks made of Coming borosilicate, fused silica, and ULE glasses are such notable mirrors as the 3.6 meter ESO, 4.0 meter Canadian, 2.7 meter McDonald Observatory, 2.4 meter Hubble Space Telescope, and several 4.0 meter thin meniscus blanks. Coming ULE Ultra Low Expansion glass was the preferred material of choice for the Subaru primary mirror because of its highly homogeneous, zero thermal expansion coefficient.