Viewing DVDs

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jjtr1
Posts: 33
Joined: Sat May 07, 2022 8:51 am

Viewing DVDs

#1 Post by jjtr1 » Sat May 21, 2022 4:41 pm

Hi,

I'm wondering if there is a cheap way of viewing the pits and lands of a DVD disc. The problem is that the data layer is buried 0.6 mm below surface. 40x objective usually doesn't have sufficient working distance. Is there a way other than buying an expensive LWD objective?

DVD, CD and Blu-ray parameters:
https://en.m.wikipedia.org/wiki/Compact ... DVD_BD.svg

MichaelG.
Posts: 3976
Joined: Mon Apr 10, 2017 8:24 am
Location: North Wales

Re: Viewing DVDs

#2 Post by MichaelG. » Sat May 21, 2022 9:07 pm

it doesn’t answer your question, but I’m guessing you might find this of interest:
https://www.researchgate.net/publicatio ... prints_Too

MichaelG.
.

P.S. I think the answer is … that’s the sort of job that LWD objectives are designed for.
… but you don’t necessarily need an expensive one !
Too many 'projects'

MichaelG.
Posts: 3976
Joined: Mon Apr 10, 2017 8:24 am
Location: North Wales

Re: Viewing DVDs

#3 Post by MichaelG. » Sat May 21, 2022 9:09 pm

Sorry :oops: … Double post
Too many 'projects'

Chas
Posts: 422
Joined: Tue Jan 19, 2021 3:11 pm

Re: Viewing DVDs

#4 Post by Chas » Sun May 22, 2022 8:48 pm

About 8:30 into this :
https://www.youtube.com/watch?v=GuCdsyCWmt8
(peeled it off with sticky tape).

jjtr1
Posts: 33
Joined: Sat May 07, 2022 8:51 am

Re: Viewing DVDs

#5 Post by jjtr1 » Wed May 25, 2022 8:59 pm

Chas wrote:
Sun May 22, 2022 8:48 pm
About 8:30 into this :
https://www.youtube.com/watch?v=GuCdsyCWmt8
(peeled it off with sticky tape).
:-D Sticky tape for CDs and Xacto knife for DVDs. Sometimes brute force wins over fine optics :) I might try that.

I was wondering that maybe if I shortened the optical tube, I could extend the working distance of a 40x objective a bit to reach 0.6 mm into the DVD. I don't know whether the spherical aberration thus introduced would tend to compensate, or aggravate one caused by the too thick "cover slip".

Too bad I don't have an epi-illuminator. They seem to cost twice what I paid for my entire Alphaphot.

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