The making of 30 in telescope - 29, mirror cell

自製天文望遠鏡 牛頓望遠鏡 杜蘇式 卡式 設計和磨鏡方法<br>
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Chanlunlun
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註冊時間: 週四 09 10月, 2003 21:06

The making of 30 in telescope - 29, mirror cell

文章 Chanlunlun » 週四 05 1月, 2006 10:52

Dear ATMs,

After much delaying ( Takahashi castle trip, examination of students…. ) the mirror cell designing stage is finally commenced. As a general routine we scrutinize various cell designs using the famous freeware PLOP.

It is in the earlier stage that we have decided to use a 27 points floatation cell. After careful calculations by PLOP it is to our surprise that a 27 points cell gives a residue mirror sag of about 1/6 wave( still below Reyleigh criterion ) while at the same time a 18 points cell gives a mirror sag of about 1/4 wave, a little worse than the 27 points cell, but certainly cannot be distinguished visually during star observation.

It seems that the 27 points cell does not deserve to pay much attention to as the work involved in making such cell is enormous. On the other hand the we are well experienced in making 18 points cell, not to mention the save of cost and labor in doing so.

So the decision is final – the 30 inch mirror will be supported by a 18 points cell.

This decision will greatly simplify our work.

Best regards
Chan Yuk Lun
5-1-2006
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30inch_18pts.jpg
The color contour of 18 pts. cell as given by PLOP. It has a residue mirror sag of about 1/4 wave p.v.
30inch_18pts.jpg (15.1 KiB) 已瀏覽 6373 次
30inch_27pts.jpg
The color contour of 27 pts. cell as given by PLOP. It has a residue mirror sag of about 1/6 wave p.v.
30inch_27pts.jpg (14.77 KiB) 已瀏覽 6373 次

Chanlunlun
夸克星
文章: 3847
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週四 05 1月, 2006 15:42

Dear ATMs,

The pads ( each pad contains three supprting points ) for the mirror cell has just been finished. I hereby attach a picture of them and you are free to supply your comments. As usual my craftmenship is poor.

Best regards
Chan Yuk Lun
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30_pad.jpg
Teh pads are made of garbage wood, cheap and easy to maneuver.
30_pad.jpg (70.25 KiB) 已瀏覽 6334 次

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