The purpose of this experiment was to determine the distance between grooves on a CD by shining a laser on the grooves, observing the interference pattern resulted on a piece of paper, and making measurements to calculate the d.
Experiment
Set up to calculate the wavelength of the laser used
The wavelengh of the laser was calculated to be 668 nm
CD used in experiment
Set up to measure the distance between grooves on the blue CD.
Conclusion
The theoretical groove distance was 1600 nm while the experimental grooves distance was determined to be 2992 nm ± 212 nm, with a percent error of 87%. Therefore, the experimental data did not lie within the uncertainty of the equipment, and it is off by a factor of 2. Possible errors could be there was angular separation: the CD was not parallel to paper screen; the three diffracted light dots on the screen were not completely horizontal. Also, the scratches on the CD could cause a significant deviation of the groove distance from its true value because the scartches can destroy the uniform distance between grooves, thus the distance we measured here could be the interference pattern from a couple scratches on the disk instead of the grooves.
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