CD Diffraction

The purpose of the experiment is to measure the distance d between the grooves on a CD for the Easy Listening Music Studio company.

This is accomplished by allowing a Helium Neon Gas Laser--which has a wavelength of 630 nm--to strike the disk normally.  As a result the first and second order maxima appear on the screen or white board.

(Above: The Set Up)


The distance from the slits or groves to the screen is a distance L 51 +/- 1 cm.  Moreover after the experiment was conducted, the lengths of the first and second-order maxima to the zeroth-order maxima are x-1 22.5 +/- .5 cm and x-2 68.8 +/- .5 cm respectively.  These values were used to find the relative angles, atan (x/L) = theta.


Calculations:

Key Equation: d*sin(theta) = m*lambda , where m is the maxima number and d is the distance between the grooves.

Note that the d set equal to 51 cm in the above photograph is really L, the distance from the slit to the screen or whiteboard.  Also the second equation should be multiplied by two since it is the second-order  maxima, m=2.