# Laser Interference and Diffraction, single and double slit experiment?

## Homework Statement

I did the single slit light diffraction lab. The diode laser we used was 630-680 nm. It produced an image very much like the one on this page:

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/fraungeo.html#c1

How does having multiple wavelengths in the laser change the pattern produced? What would it look like if the laser only produced one wavelength?

Before I turn my lab in, I want to make sure I have the right answer...

## Homework Equations

L=wave length

y = (mLD / a)

I think the size of the minima (dots) would be smaller, and possibly the spacing between them will be closer together. Can someone clarify?

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Redbelly98
Staff Emeritus
Homework Helper
I think you misunderstand the meaning of "630-680 nm". There is only one wavelength for the laser, and it is somewhere in that range. The laser does not emit all wavelengths in that range.

fluidistic
Gold Member
I also think your laser had 1 wavelength (at least in the visible spectra). If it had say a wide range of values of wavelengths, the smaller wavelengths would make a pattern that has less space between maximum/minimum of intensities compared to the pattern the greater wavelengths would make.

fluidistic
Gold Member
I think you are correct. This would explain the "smuged" look I saw on the CD diffraction pattern when using my Night Vision Scope. Two of the dots were close together (the 808nm and 1064nm) while the green naked eye visible 532nm dot was more distant in the series of dots making up the DIFFRACTION PATTERN.

Thanks,

David
I'm not sure I understand fully what you mean. But the green color wavelength would be less diffracted than the infra-red’s ones.
In other words almost all the intensity of the green color would be very close to the front of the aperture while the infra-red would have maxima separated by a greater distance than the ones of the green color. And the intensity of infra-red waves wouldn't be as much concentrated right in front of the aperture compared to the green color's.