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Robert9
25-09-2009, 05:41 PM
Has anyone tried to use a section of a DVD as a reflection grating? Line pitch is 740Nm which, if my calcs. are right gives lines/mm = 1350.
bojan
25-09-2009, 06:17 PM
I tried on very bright objects, works for visual but do not expect quality.. plastic is not flat enough.
sheeny
25-09-2009, 06:23 PM
Yeah, but only as a handheld visual spectroscope. There are some threads here somewhere discussing CD and DVD gratings...

Al.
Robert9
25-09-2009, 06:48 PM
Thanks guys. I've just been tossing out a few old disks and the spectral effects set me wondering.
Have to get together for an eyeball sometime Bojan.

Robert
Merlin66
25-09-2009, 08:19 PM
Robert,
Practical Astronomical Spectroscopy by Tonkin has a whole chapter on CD/DVD gratings by David Randell.
Over on the Astronomical Spectroscope Yahoo forum
http://tech.groups.yahoo.com/group/astronomical_spectroscopy/?yguid=322612425

One of the members "Jack" is VERY supportive of CD/DVD gratings!!
I found them next to useless for anything other than showing what a spectrum looks like! HOWEVER, I would like to try the "spare" blank and clear disks that come in those stacks of CD's. I think there MAY be potential to use one as a transmission grating. Don't know anyone who has actually trialed it yet - want to be the first???
bojan
26-09-2009, 04:55 PM
No problems :thumbsup:
Robert9
28-09-2009, 11:00 AM
Oh how I hade colds in da dose!
I checked the on-line catalogue of our local library which has quite a good collection on astronomy, but found only one book on spectroscopy. Someone had reviewed it and said it was chemically oriented; so of no use.
I've just been burning some coasters (discovered my burner had died) and was wondering what to do with them. Good for keeping birds off fruit trees etc. Perhaps also for spectroscopy. Bojan, I'm a bit surprised that they are not flat enough. They are multi-layered which gives them a reasonable stability (yes, they do flex). But flat? I would have thought that flatness, considering the way they DVDs work, was rather critical. But then flat and optically flat, on second thoughts - I agree, there is probably a big difference.
Off for another cup of lemon tea with honey!

Robert
bojan
28-09-2009, 02:03 PM
It is :thumbsup: