First Surface Mirror?

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mnmyco
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First Surface Mirror?

#1 Post by mnmyco » Tue Oct 09, 2018 8:54 pm

Has anyone ever tried old hard drive platters as a first surface mirror? They are incredibly smooth and very reflective. I have several laying around, but I have no need to cut them and no way to test the outcome.

mnmyco

mnmyco
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Re: First Surface Mirror?

#2 Post by mnmyco » Tue Oct 01, 2019 7:55 pm

I found this website about using hard drive platters in laser as mirrors. In case anyone is interested to read it I posted it here. I think I will try cutting some soon.

http://www.imajeenyus.com/optical/20140 ... ndex.shtml

MNMyco

MichaelG.
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Re: First Surface Mirror?

#3 Post by MichaelG. » Tue Oct 01, 2019 8:01 pm

Interesting link ... Thanks

MichaelG.
Too many 'projects'

MicroBob
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Re: First Surface Mirror?

#4 Post by MicroBob » Wed Oct 02, 2019 11:45 am

These hard discs have a look as if they might not reflect the whole light spectrum equally so I would check the image quality before spending much time implementing them somewhere.

mnmyco
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Re: First Surface Mirror?

#5 Post by mnmyco » Fri Oct 18, 2019 4:47 pm

Good point. Do you have any suggestions for a good way to test that? Especially if it does not involve cutting the disks?

MNMyco

MicroBob
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Re: First Surface Mirror?

#6 Post by MicroBob » Fri Oct 18, 2019 7:57 pm

Well, I just took one and used it for my fluorescence condenser side lighting unit. The surface looks perfectly silvered to me, I didn't find a hint to uneven spectral reflection.
This was out of my stack of optic DIY material, a 2,5'' disc. It was made from some kind of glass. I tried to cut it with a glazers diamond - not good. Then with a diamond dremel wheel - not much better. In the end I needed two discs to get a suitable but ugly shard!
Another source are Polaroid cameras (be careful - prices mith increase already) or microfiche readers.

Bob

Hobbyst46
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Re: First Surface Mirror?

#7 Post by Hobbyst46 » Fri Oct 18, 2019 8:03 pm

A metallic first mirror for dental and mouth treatments is cheaply sold on eBay and is (I am sure) much easier to cut than a hard disk; I used an ordinary hacksaw, 24-32 TPI grade should be good. No diamond tools were needed.
Hard disks are useful as-are, spinning shiny gadgets. One reason they have been named called "hard" is the difficulty of cutting them, in contrast to floppies which could be cut with simple scissors :twisted:
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

MicroBob
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Re: First Surface Mirror?

#8 Post by MicroBob » Fri Oct 18, 2019 8:26 pm

Hi Doron,
what are the dental mirrors made of? Aluminium?
If precise size is important the hard discs I used are not great. The diamond wheel didn't cut them well (maybe a question of the right wheel) and the mirror got hot which induces cracks. With patience and water cooling it will be possible to cut it well , but this is quite an effort. On the other hand side it can be expected that they stay very flat which would be a big advantage for the observation light path. In my case a roughly oval shard was good enough so it didn't matter. I can imagine that a normal abrasive wheel would have cut this material better. I expected the hard discs to be aluminium based - these were not.

Bob

Hobbyst46
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Re: First Surface Mirror?

#9 Post by Hobbyst46 » Fri Oct 18, 2019 9:16 pm

Hi Bob
Dental mirrors are made of steel - some kind of stainless. Thickness about 1.5mm. They are coated, and the coating is fairly strong and does not chip off.
They are flat and optically good.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

mnmyco
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Re: First Surface Mirror?

#10 Post by mnmyco » Fri Oct 18, 2019 10:49 pm

There are two types of hard drive disks. Some are made of aluminum and others are made of ceramic. Seems most people that cut them use a jewelers saw and some sort of cutting fluid I believe. Maybe some day I will give making a DIY water jet cutter. I know it has been done.

MNMyco
Last edited by mnmyco on Sat Oct 19, 2019 1:50 am, edited 1 time in total.

Scarodactyl
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Re: First Surface Mirror?

#11 Post by Scarodactyl » Fri Oct 18, 2019 11:12 pm

Could a dental mirror be used for an image-reflecting sirface? I have some old sz7 trinocular add-ons with bad mirrors, and sizing a glass fsm is a pain.

Hobbyst46
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Re: First Surface Mirror?

#12 Post by Hobbyst46 » Sat Oct 19, 2019 12:02 pm

Scarodactyl wrote:
Fri Oct 18, 2019 11:12 pm
Could a dental mirror be used for an image-reflecting sirface? I have some old sz7 trinocular add-ons with bad mirrors, and sizing a glass fsm is a pain.
I cannot testify for the imaging quality (never tried); what are the allowed/wanted dimensions (l/w/t) of the replacement metallic fsm ?
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

MicroBob
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Re: First Surface Mirror?

#13 Post by MicroBob » Sat Oct 19, 2019 2:58 pm

What would be a good test for a mirror? Looking into it with a pair of binoculars at a subject with fine detail?
Ordinary sheet metal is not that flat so it is the question whether they ground it flat or not.

Hobbyst46
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Re: First Surface Mirror?

#14 Post by Hobbyst46 » Sat Oct 19, 2019 3:31 pm

Scarodactyl wrote:
Fri Oct 18, 2019 11:12 pm
Could a dental mirror be used for an image-reflecting sirface? I have some old sz7 trinocular add-ons with bad mirrors, and sizing a glass fsm is a pain.
MicroBob wrote:What would be a good test for a mirror? Looking into it with a pair of binoculars at a subject with fine detail?
Ordinary sheet metal is not that flat so it is the question whether they ground it flat or not.
I still have a leftover piece from the dental mirror. The mirror was large enough to cut out 3 pieces for my microscopes. If some of you folks can conceive a quick simple test of imaging, that can be done with basic means, I might be able to run it and report.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

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