The arrival of 24 inch mirror blanks.
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
The arrival of 24 inch mirror blanks.
Dear ATMs,
The 24 inch mirror blanks have arrived. Both the mirror and the tool are of thickness 1 inch, diameter 24 inches.
The focal length of the mirror has been decided to be at 84 inches. i.e. at a focal ratio of 3.5. We also decided to grind and polish the mirror by a full size tool and full size lap. The figuring of the mirror will be done by a small lap, only 3.5" in diameter.
The method of testing the prarboloid has not yet been fixed. Any one who has any idea about testing of big mirror please do not hesitate to offer your opinion. You are always welcome.
Hofefully the telescope will be finished before June this year.
Best regards
Chan Yuk Lun
16-1-2003
The 24 inch mirror blanks have arrived. Both the mirror and the tool are of thickness 1 inch, diameter 24 inches.
The focal length of the mirror has been decided to be at 84 inches. i.e. at a focal ratio of 3.5. We also decided to grind and polish the mirror by a full size tool and full size lap. The figuring of the mirror will be done by a small lap, only 3.5" in diameter.
The method of testing the prarboloid has not yet been fixed. Any one who has any idea about testing of big mirror please do not hesitate to offer your opinion. You are always welcome.
Hofefully the telescope will be finished before June this year.
Best regards
Chan Yuk Lun
16-1-2003
- 附加檔案
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- Mr. Sodium and the 24 inch mirror blank. Mr.Sodium will be one of the mirror grinding team for this 24 inch telescope project.
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
Dear Mr. Subaru,Subaru 寫:
用full size tool磨完之後塊主鏡會唔會好薄?
For grinding and polishing of big mirror, a full size tool is a must. While a sub-diameter tool can also do the job quite well, it suffers from drawback of low efficiency.
You may have a lot of labour saved when using full size tool. All we need to do is to close monitor the edge thickness during rough grinding.The goal is to keep the edge as thick as possible. As experience from the 20 mirror inch tells, we can retain 100% edge thickness even with a full size tool.
Best regards
Chan Yuk Lun
16-1-2004
- david_kmng
- 白矮星
- 文章: 960
- 註冊時間: 週五 11 7月, 2003 00:10
- 來自: 草根階層
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- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
-
- 夸克星
- 文章: 3847
- 註冊時間: 週四 09 10月, 2003 21:06
oldsaltfish 寫:I am afraid the thickness is not enough
Dear Mr. OldSaltFish
This is also my worry. However as analysised by finite element method, the deformation of the mirror is verY very small even at 24:1 thickness ratio, under a 18 point floatation cell.
So we just go for it.
Best regard
Chan Yuk Lun
5-2-2004
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