Imaging CDs, DVDs or other optical media under SEM

  • Context: Graduate 
  • Thread starter Thread starter Septim
  • Start date Start date
  • Tags Tags
    Imaging Optical Sem
Click For Summary

Discussion Overview

The discussion revolves around imaging CDs and DVDs using scanning electron microscopy (SEM), focusing on the necessary preparation for different types of optical media, such as CD-Rs, CD-RWs, and CD-ROMs. Participants share their experiences and observations regarding the imaging process and the characteristics of the media.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about the preparation needed for imaging various types of CDs and DVDs, noting the potential opacity of layers to the electron beam.
  • Another participant shares their imaging experience with a CD-R, mentioning that they broke the disc to access the aluminum layer and later imaged the polycarbonate surface, but did not achieve satisfactory results from the aluminum layer.
  • A participant questions why the observed track pitch was half of the expected value, suggesting a need for clarification on the definition of track pitch.
  • One participant clarifies that track pitch refers to the full distance from the center of one line to the center of the next, rather than the width of the lines.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best preparation methods for imaging CDs and DVDs, and there are differing views on the interpretation of track pitch measurements.

Contextual Notes

The discussion includes uncertainties regarding the specific preparation techniques required for different types of optical media and the implications of track pitch measurements, which remain unresolved.

Septim
Messages
166
Reaction score
6
Greetings,

After getting some training I have access to my universities SEM facilities and I would like to image CDs and DVDs with it(, I know that these consist of many layer which may not be transparent to the e-beam so they might need some preparation. Does anyone have any idea? I am reluctant since I could not exactly figure out what kind of preparation is required for say CD-Rs CD-RWs or directly CD-ROMs. Any suggestions and help is appreciated.

P.S : I found this particular website which might give you a hint about the kind of preparation involved.
 
Science news on Phys.org
Here is an idea of what you'll see

image027.JPG
 
  • Like
Likes   Reactions: Septim
Actually I got the following images where the track pitch is nearly the half of the value indicated on the web and your post (0.8μm ). In order to image the CD-R(Not a CD-ROM), first I broke it carefully then I proceed with the aluminium layer just under the label which did not give much of an image and later I decided give the polycarbonate surface a go and got the resulting images at different magnifications.

CD23.jpg
CD24.jpg
CD25.jpg
 
Last edited:
  • Like
Likes   Reactions: mfb and Greg Bernhardt
Septim said:
Actually I got the following images where the track pitch is nearly the half of the value indicated on the web and your post (0.8μm ). In order to image the CD-R(Not a CD-ROM), first I broke it carefully then I proceed with the aluminium layer just under the label which did not give much of an image and later I decided give the polycarbonate surface a go and got the resulting images in different magnifications.

View attachment 77663 View attachment 77664 View attachment 77665
You have any idea why the track pitch was half of the value it should be?
 
Track pitch is the full distance from one line center to another, not the width of those lines.
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
3K
Replies
8
Views
5K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 12 ·
Replies
12
Views
7K
  • · Replies 37 ·
2
Replies
37
Views
15K
  • · Replies 13 ·
Replies
13
Views
4K