CD Diffraction

CD Diffraction

Objective

The objective of this lab is to determine the size of the grooves that are located on a CD or DVD

Procedure

Equipment:

Laser

Compact Disk

Meter Stick

A Screen with a hole in the middle.

Set up Diagram

Using a Screen with a hole through it arrange a laser such that it hits the surface of the CD perpendicularly.Move the CD around as needed in order to see a diffraction pattern coming from the CD to the screen. Make it so that the first order maxima will appear on the screen on either side of the hole the  laser is coming through. Measure the distance from the screen to the CD and record the distance between the maxima on the screen from the resultant diffraction pattern. for the laser used λ=633 nm the Length L=3.8 ± 0.02 cm  and the distance between maxima was    2x= 2.5 ± 0.1 cm

Calculations

Using these calculations it is seen that our error is high from the standard manufacturer's standard value of 1600 nm. This error is due to the the fact that our experiment was not stable. We couldn't get the diffraction to show on our screen so for the experiment we held the CD (off the table) in order to get the diffraction to show on the screen. As a result our measurements were not very accurate because the CD was moving around slightly.However within our uncertainty we came up with a 9.31% deviation from the standard value.