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I've tested four different kind of 3D printing materials to see if they are transparent in any part of the spectrum.

https://www.dropbox.com/s/14mnhejcaofft ... t.pdf?dl=0

Best regards,
Paul

Hello,

I thought, the question was concerning STABILITY not TRANSPERENCY.(?)

Berthold

I got some remarks for Oliver Garde that 3D printed objects were transparent in the infrared. There was even suggested that it would be like using a transparent box. This test clearly shows that this is not the case. Of the four tested only PLA shows transparency. I almost excursively use ASA which appears to be completely opaque in the visible and near infrared.
Testing thermal and mechanical stability is something on my list. I recently acquired a role of Nylon filament with carbon particles. I’m still learning to print with this stuff but this material should be more rigid and thermally stable then ASA. We’ll see.

Paul

Hi - that's true... - but this is here a different thread ..

...my original question was about stability and use of printed parts - and also for devices connect by fiber. But however, if transparency is also a relevant question in this context, I'm happy to learn about it.. -

Meanwhile somebody else told me that parts created by 3D printers might be very fragile and does not allow mechanical stress - but looking on the LowRes Spectrograf, major parts looks to be printed and have to tolerate finally the weight of CCD... maybe the different printer technologies has some influence on stability.

Georg.

-----Ursprüngliche Nachricht-----
Von: Berthold Stober [mailto:fg-spek-tech@vdsastro.de]
Gesendet: Freitag, 9. März 2018 20:29
An: fg-spek-admin@vdsastro.de
Betreff: [fg spektroskopie] Re: testing 3D materials for transparency issues

Link zum neuen Beitrag: http://forum.vdsastro.de/viewtopic.php?t=5122#p31244

Hello,

I thought, the question was concerning STABILITY not TRANSPERENCY.(?)

Berthold

Hi Paul,

Your graph show the IR transparency only for wavelength up to 750nm (near IR) but IR wavelength go deeper to 1um-1mm.

have a look on this two posts show transparency of pastics bags in IR :
https://physics.stackexchange.com/quest ... ared-light
https://physics.stackexchange.com/quest ... ared-light

Of course you find that PETG, ASA or Nylon CF15 is more opaque, but may be these materials can pass wavelengths > 750nm and the IR can pollute the background of the spectrum as will the light pollution. A amateur CCD camera can record the IR until 1um.

So I think it would be nice to cover your spectrograph with aluminum tape that is opaque to IR like this one :
https://www.amazon.co.uk/No1-Packaging- ... 566663416X

Good point Olivier! I did not think of that.
So when I take a simple darkframe there should be a difference between a darkframe taken 'true' the LOWSPEC and one taken from the same camera covered by a metal cover.
I haven't done that yet but I've looked at the difference in darks from the situation where the DADOS was attached and when the LOWSPEC was. In both cases 30x120 sec averaged.
In these situations I cannot see any significant differences.