Calculating Bit-Density of a CD using AFM Images

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SUMMARY

The discussion focuses on calculating the bit-density of a CD using Atomic Force Microscopy (AFM) images. The user manually counted 224 bits in a 900µm² image and calculated the total active area of the CD to be 9,085µm². The proposed calculation of total bits, derived from the ratio of bits to area, resulted in an implausible storage capacity of 0.00215640640258789MB, raising concerns about the accuracy of the radius measurement and the area calculations. The discrepancy highlights the need for accurate measurements and verification of the radius used in calculations.

PREREQUISITES
  • Understanding of Atomic Force Microscopy (AFM) imaging techniques
  • Knowledge of geometric area calculations for circular objects
  • Familiarity with bit-density concepts in optical media
  • Basic arithmetic operations for unit conversions and density calculations
NEXT STEPS
  • Verify the radius measurement of the CD and recalculate the total area
  • Research the standard bit-density of CDs and how it relates to physical measurements
  • Explore the implications of AFM imaging on data storage calculations
  • Learn about error analysis in measurements and calculations in physical sciences
USEFUL FOR

Researchers in materials science, engineers working with optical media, and anyone involved in data storage technology who seeks to understand the relationship between physical measurements and data capacity.

SarahBoberra
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We took AFM images of a CD in lab. Manual counting provided that there were 224 bits in the 900µm^2 image I have. Based on this I want to determine the bit-density of the whole CD.

The total active area for the disc is the total area minus the inner inactive are of the disc. The total area was calculated using a radius of 58.5µm and was found to be 10,746 µm^2. The inner inactive area of the disc was found to be 1,661µm^2. Therefore, the total active area of the disk was 9,085µm^2.

Shouldn't the next step be to take (224 bits/900µm^2)*9,085µm^2 to get the total number of bits? For this I get 2,261.156 bits, but it can't be right because it would mean that the whole CD had only 0.00215640640258789MB of storage! I know that CDs have ~650MB of storage. What did I do wrong? Please?
 
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Radius of 58.5µm doesn't look correct to me. Are you sure you mean µm?
 
the area looks waaaay off!
 

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