Near the center of the CD

Images made through a microscope. All subject types.

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Didier_Micro
Posts: 40
Joined: Sat Nov 21, 2020 1:48 pm
Location: Bailly Near Versailles

Near the center of the CD

Post by Didier_Micro »

Dear Microscopists,

I just had the idea to look at a computer CD under the microscope.
This is what it looks like.
CD - Didier Barbet
CD - Didier Barbet
.
CD - Obj X05 - Didier Barbet
CD - Obj X05 - Didier Barbet
.
CD - Obj X05 3D - Didier Barbet
CD - Obj X05 3D - Didier Barbet
.
CD - Obj X10 - Didier Barbet
CD - Obj X10 - Didier Barbet
.
CD - Obj X20 - Didier Barbet
CD - Obj X20 - Didier Barbet
.
CD - Obj X50 - Didier Barbet
CD - Obj X50 - Didier Barbet
.
Hoping that it will interest you.

Regards
Didier Barbet

Lou Jost
Posts: 5944
Joined: Fri Sep 04, 2015 7:03 am
Location: Ecuador
Contact:

Re: Near the center of the CD

Post by Lou Jost »

Interesting. So where are the bits?

Didier_Micro
Posts: 40
Joined: Sat Nov 21, 2020 1:48 pm
Location: Bailly Near Versailles

Re: Near the center of the CD

Post by Didier_Micro »

Hello Lou,

This is only a border near the center of the disk.
The pieces of information are stored on the silver part.
On the silver part, there is a protective layer, below a reflecting layer, and below a recording layer where the bits are.

Regards
Didier

Olympusman
Posts: 5090
Joined: Sun Jan 15, 2012 12:31 pm

Re: Near the center of the CD

Post by Olympusman »

There is a difference between a data CD-R and a Music CD-R. A Music CD-R has, as I recall, three dots in that inner band that identify it as a Music CD-R to devices dedicated to making a music CD. These tell the recorder that this is a Music CD-R. Music CD-R discs cost more than a data CD-R because the price difference goes into a pool shared by music labels to address royalty issues arising from piracy from home-grown copies sharing commercially produced music CDs.

Mike
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

iconoclastica
Posts: 486
Joined: Sat Jun 25, 2016 12:34 pm
Location: Wageningen, Gelderland

Re: Near the center of the CD

Post by iconoclastica »

My audio cd-player accepts both music and data cds. Only half of the data cds are rejected. Which I always thought strange, since audio data allow for some errors whereas a data backup must be byte perfect. If the test is in those dots, it seems not too reliable if also some data cds are accepted.
--- felix filicis ---

Olympusman
Posts: 5090
Joined: Sun Jan 15, 2012 12:31 pm

Re: Near the center of the CD

Post by Olympusman »

But the question is, does your audio player also record? I have downloaded audio in a computer and written it to CDs that will play anywhere - home car whatever. Some player/recorders such as my SONY are very uppity about what CDs they will record on. In other words, it must be a Music CD. This makes perfect sense since SONY is also in the music (and movie) business. However, I have found that if a CD is written to the RED BOOK specifications in a computer, they will usually play in anything.

Mike
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

iconoclastica
Posts: 486
Joined: Sat Jun 25, 2016 12:34 pm
Location: Wageningen, Gelderland

Re: Near the center of the CD

Post by iconoclastica »

Olympusman wrote:
Wed Oct 06, 2021 1:13 pm
But the question is, does your audio player also record?
Nope, not even if I'd put a blank music score paper in :D It's that kind of old fashioned single function device. But I get your point now.
--- felix filicis ---

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