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AlexCdeP
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I have just completed an experiment on principles of lasing, constructing a laser and measuring the beams intensity distribution. This distribution of the beam was measured using a detector mounted on a traveling microscope. The detector had a pinhole cover such that only a small fraction of the beam entered the detector at once, and from this I could measure the current from the detector on an ammeter against the horizontal displacement. Now I must be going crazy because I spoke to a demonstrator in the lab and she said I can just plot this current because current and intensity are proportional. Indeed I proceeded to plot the data and the measurements fitted the predicted values. However I checked and current is not proportional to intensity, it is proportional to the square root of the intensity which mucks everything up. Can anyone think what I have missed.
P=I[itex]^{2}[/itex]R
and I=[itex]\frac{P}{A}[/itex]
so I[itex]^{2}[/itex][itex]\propto[/itex]Intensity
The plot comes out as a Gaussian distribution so I=I[itex]_{0}[/itex]e[itex]^{\frac{x}{w_{0}}}[/itex]
w is the beam width, I is intensity and, x is the horizontal position.
So if the current were proportional to the square root of intensity we wouldn't get this distribution.
Thanks in advance to anyone that can help.
Homework Equations
P=I[itex]^{2}[/itex]R
and I=[itex]\frac{P}{A}[/itex]
so I[itex]^{2}[/itex][itex]\propto[/itex]Intensity
The Attempt at a Solution
The plot comes out as a Gaussian distribution so I=I[itex]_{0}[/itex]e[itex]^{\frac{x}{w_{0}}}[/itex]
w is the beam width, I is intensity and, x is the horizontal position.
So if the current were proportional to the square root of intensity we wouldn't get this distribution.
Thanks in advance to anyone that can help.