www.astrocafe.hk

I like to do experiment & DIY. Star testing a telescope needs a bright star. However, bright stars are not always present. Even u got a bright star, the transparency & seeing will affect the test result. So an artificial star is a resolution. BUT artificial stars are not cheap. 社長’s artificial star costs more than HK$2000! So I do it by myself. I borrowed the design from http://hubble-optics.com/artificial-stars.html
I asked my friend, a D&T teacher, to use laser to drill 5 holes on an acrylic plate. The sizes of the holes are 50um, 100um, 150um, 200um and 250um. Just put the acrylic plate in front of an LED torch and 5 artificial stars are formed! One can buy a powerful LED torch from Ap Liu street easily. Today, I tested my FS60C by this DIY artificial star at 178X. The diffraction rings are frozen and no more seeing problem. This provided a convenient, though reliable telescope testing. I have made 10 artificial stars. There are 9 spares. I will give them to the members of http://www.astrocafe.hk for free on the basis of first come first served. If u want it, please reply this thread. 社長 one is reserved for u. Can u help to distribute the artificial stars?

Thanks Willis for this great little tool, yes, please reserve one for me, and I can keep it in my office and help distribute it

香港以外的Astrocafers，因為這個東西很輕，用信封寄便成，空郵遠至加拿大也不超過三元，中國內地、台灣及東南才一元多，所以我免郵費寄給他們吧。

Astrocafers have a number of telescopes, it's time to setup simple yet powerful tools to test it. Its also good for optical alignment.

我又要......

So does this mean that I can, for example, collimate my C8, in the physics lab?

If so, please reserve one for me.

David 寫:So does this mean that I can, for example, collimate my C8, in the physics lab?

If so, please reserve one for me.

Yes! u can use it to collimate C8. Since the physics lab is not very long, the back focus of C8 may not support it. u may need to do it in the corridor.

Reserve list:
1. 社長
2. Lewis
3. David

Reserve list:
1. 社長
2. Lewis
3. David
4. xiaoer

Willis, as I need to pass you the lighter counter weight for the EQ1, may be I can ask Ah Ying to collect these from you and mail to everybody who are interested.

社長 寫:Willis, as I need to pass you the lighter counter weight for the EQ1, may be I can ask Ah Ying to collect these from you and mail to everybody who are interested.

Willis can pass mine to his colleague (you know who) because I will probably see her some time this week.

I am interested to have one also...very interesting stuff....
But I am live in Malaysia. Not sure 社长 can mail to me or not....

universe24 寫:I am interested to have one also...very interesting stuff....
But I am live in Malaysia. Not sure 社长 can mail to me or not....

Chin兄，沒問題的，因為東西很輕，我放進信封寄給你就是了。

Reserve list:
1. 社長
2. Lewis
3. David
4. xiaoer
5. universe24

請幫我留一個　　下次寄貨時一並寄到台灣　　謝謝　　Henry Wu (Taiwan)

Reserve list:
1. 社長
2. Lewis
3. David
4. xiaoer
5. universe24
6. Henry Wu

感谢社长。
还有感谢willis的用心。

另外，我想问下willis，那个laser切割，是否可以也切割出一条裂缝或者一条球面弧度裂缝，成为光谱仪的slit？

universe24 寫:感谢社长。
还有感谢willis的用心。

另外，我想问下willis，那个laser切割，是否可以也切割出一条裂缝或者一条球面弧度裂缝，成为光谱仪的slit？

I think the laser cutter can make a striaght & curved slits. But how precise the curvature I need to check with my colleague. I am not the one who operate the laser cutter...

I see. Is that the laser can cut any material? Can cut glass?
Let say I got a rectangle first surface mirror, I would like to cut a slit on it. Is that possible?
Thank you very much.

It is a low power laser used in secondary school. It can only cut plastic.

I see I see...thanks again.

Hi Willis兄…可否預留一件給我呀？Thanks!

Reserve list:
1. 社長
2. Lewis
3. David
4. xiaoer
5. universe24
6. Henry Wu
7. cwlam