| 摘要 |
1,167,895. Mirrors. OWEN-ILLINOIS Inc. Jan.3, 1967 [Jan.3, 1966], No.255/67. Heading G2J. [Also in Division C1] A light-weight, low expansion glass-ceramic telescope mirror blank, comprises two glassceramic members 13, 14 Fig.1 or 23, 24 Fig.5 disposed in facing relationship with at least one glassceramic spacing member 11, 12 or 25 disposed between and sealed thereto so as to contact each of the facing surfaces 15, 16 or 27 over only small portions of the area of the surfaces, the mirror blank having an average linear coefficient of thermal expansion within the range of 10 Î 10<SP>-7</SP> to -10 Î 10<SP>-7</SP> per ‹C. over the range from 0‹ to 300‹C. The compositions are preferably SiO 2 -Al 2 O 3 - Li 2 O glasses and the compositions used are as disclosed and claimed in Specification 1,124,002. As shown in Fig.1, inter-locking spacing members 11, 12 having co-operating slots (19), (20) which link to give the grid shown, and may or may not seal the spacing members together during sealing to the outer members 13, 14. Serial Nos. 1072421, 1167896 and 1167897 are referred to. |
