Parabolization of 24 inch continues

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>
佛科試鏡法 佛科刀片儀 光柵試鏡法 光柵片
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Chanlunlun
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文章: 3834
註冊時間: 週四 09 10月, 2003 21:06

Parabolization of 24 inch continues

文章 Chanlunlun » 週一 15 3月, 2004 13:31

Dear ATMs,

The parabolization of the 24 inch mirror continued. After nearly 5 hours of parabolization by the 14 inch lap, there was only little progress recorded. We think that it is high time for us to prepare the 9.5 inch parabolization specialized lap.

The second Foucalt test was also carried out and the result showed that the mirror was still an oblate spheroid, with a little bit corrected towards a sphere. It showed that the 14 inch lap was of very low efficiency when used as a parabolization tool.

At the moment we are still employing a simple Foucalt test to guide the figuring. Later we will proceed to use the Dall null test and figure the mirror against the Dall null tester. When we get a null figure we are close to a perfect paraboloid and we will switch to the Offner tester to finalize the figuring process. The star test will be the ultimate judge. We do not use the Offner tester first because it is still not yet calibrated. Only when the mirror surface get very close to perfect paraboloid do we use the Offner tester with confidence.

This is only the beginning of the final stage, we set no time limit to end this up.

Best regards

Chan Yuk Lun
14-3-2004
附加檔案
parabolization.jpg
One of the telescope making team member trying hard to parabolize the mirror.
parabolization.jpg (66.58 KiB) 已瀏覽 10370 次
upright_3.jpg
The 24 inch mirror was set up vertically waiting for the Foucalt test.
upright_3.jpg (48.46 KiB) 已瀏覽 10370 次
tester.jpg
The Foucalt tester, a simple torch with a slit produces the light source, the knife edge is at right side.
tester.jpg (52.79 KiB) 已瀏覽 10370 次

Chanlunlun
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文章: 3834
註冊時間: 週四 09 10月, 2003 21:06

Re: Parabolization of 24 inch continues

文章 Chanlunlun » 週一 15 3月, 2004 13:37

More pictures to come
附加檔案
Foucalt_test.jpg
The Foucalt test setup, notice that the mirror is at far side. As the mirror is really big the only feasible way to set up the test is onto the floor.
Foucalt_test.jpg (39.49 KiB) 已瀏覽 10368 次
D_Day.jpg
Proceeding to test the mirror, just like a soldier engage in a field battle.
D_Day.jpg (37.49 KiB) 已瀏覽 10368 次
Oblate_spheroid_2.jpg
What we see under the tester. Obviously the mirror surface is an oblate spheroid, we may consider it just an opposite to a paraboloid.
Oblate_spheroid_2.jpg (26.98 KiB) 已瀏覽 10368 次

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Wah!
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文章 Wah! » 週一 15 3月, 2004 13:54

睇到好開心呀!
我都要努力磨支12吋鏡!!!

disablewong

文章 disablewong » 週一 15 3月, 2004 20:06

+oil ar!!~!
the mirror seem great!~~~~~
looking forward to see the finish of the mirror!!!!!!!!! 8) :shock:

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豆豸苗
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文章: 9950
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文章 豆豸苗 » 週一 15 3月, 2004 20:19

嘩. 咁反光, 我諗好天的話都可以羅出去睇下個月亮? :roll:

Chanlunlun
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文章: 3834
註冊時間: 週四 09 10月, 2003 21:06

文章 Chanlunlun » 週一 15 3月, 2004 21:19

豆豸苗 寫:嘩. 咁反光, 我諗好天的話都可以羅出去睇下個月亮? :roll:
Dear Miss BeanKitty,

The mirror, if not coated, reflects only 4% of incident light. However even accounted for that the uncoated mirror has a light grasp as same as that of a 4.8 inch refractor. So the telescope can be used to view all Messier deep sky objects, even un-aluminized, not to mention the moon and planets.

Best regards

Chan Yuk Lun
15-3-2004

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Wah!
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文章 Wah! » 週一 15 3月, 2004 21:48

但係佢的解像力比起4.8"高好多喎!!

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豆豸苗
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文章 豆豸苗 » 週一 15 3月, 2004 22:22

其實我只係見佢咁光. 諗諗下諗緊唔用副鏡, 唔用目鏡, 就咁企0係個焦點度睇月亮會點? :roll: :roll: :roll:

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扒飯撈麵
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註冊時間: 週日 06 7月, 2003 00:12
來自: 太空

文章 扒飯撈麵 » 週一 15 3月, 2004 22:58

豆豸苗 寫:其實我只係見佢咁光. 諗諗下諗緊唔用副鏡, 唔用目鏡, 就咁企0係個焦點度睇月亮會點? :roll: :roll: :roll:
reading gua?^.^

looking forward to see dso with it

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