Wiki Lab Writeup for Group 12b

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Barrett Nibling, Travis Nokes, Kurt Strovink

November 19th, 2007

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Abstract

Abstract (???)

List of Figures

List of Figures

Introduction

This experiment examines the far field diffraction pattern for a laser through a single slit. Intensity on the screen is measured with a digital camera and associated software. The inclusion of a scale on the screen makes error in position measurements trivially small. To reduce error in intensity, two pictures are analyzed; one with the iris of the camera nearly shut to get an accurate reading at the main peak and a second with the iris open to allow more accurate examination of the fringes.

Theory

Single slit diffraction refers to the tendency for light to spread out after passing through a slit. The phenomenon can be understood through Huygens principle, which states that a wave front can be treated as a line of point sources. When such a wave front hits a slit, the smaller set of point sources produces an interference pattern. To predict the minima, it is fairly simple to show that if a point at one edge interferes destructively with a point in the center, an adjacent set of points will also interfere destructively, and the argument follows for the entire slit. The minima should therefore match the pattern produced by two narrow slits spaced at half the width of the slit. A more rigorous treatment predicts the following intensity pattern [1]:

$I(\theta)\,$

$= I_0 {\left[ \operatorname{sin} \left( \frac{\pi a}{\lambda} \sin \theta \right) \right] }^2$

where a is the slit width, λ is the wavelength, and θ is the angle from the normal to the slit.

Procedure

Procedure (Barrett)

Results

Result (Travis)

Error Analysis

Error (Travis)

Conclusion

Conclusion (Barrett)

References

[1] Wikipedia - Diffraction (online at http://en.wikipedia.org/wiki/Diffraction)