Pulse Dye Laser Lab Exercise

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Pulse Dye Laser Lab Exercise

• Conducted by Graham Konecki and Rebecca Marks

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Background Information

• Dye lasers were discovered in 1966 at an IBM
  research center.
• Popular because of low cost and adjustability
• Works by stimulating the electrons in the dye
  with either pulses or continuous wave light
• Rhodamine 6G is a popular dye because its
  nontoxic, cheap, and versatile

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Goals

• To attempt to use a N2 laser to stimulate a vial
  of Rhodamine 6G to lase.
• To attempt to diffract the secondary beam to
  observe its wavelength components

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Procedure

• Clean everything with lens paper and lens cleaner
  solution
• Once Nitrogen laser is pulsing and dye is
  scintillating, adjust the vial position relative
  to the Nitrogen laser until the pulses into the
  vial appear as sharp, bright lines

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Procedure Continued

• Adjust the tilt and position of the spherical and
  flat mirrors so that the secondary beams are as
  closely aligned as possible
• Finally, redirect the beam into a diffraction
  grating
• By adjusting the angle of the diffraction
  grating, you may redirect the first order maximum
  of a particular wavelength back into the
  secondary lasing cavity.
• This allows you to adjust the primary wavelength
  of the secondary beam without having to switch
  dyes.

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Observations

• After aligning the beam we observed the image
  that was reflected off of the diffraction
  grating.
• Though the image to the left did not record well
  on the digital camera, we believed that we could
  see faint color changes in the diffracted beam.
• The left side of the beam appeared slightly green
  while the right side appeared to be slightly
  orange.

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This is reasonable right?

• Are the wavelengths we believed we observed off
  of the diffracted beam reasonable?
• Yes, because the particular dye we were using,
  Rhodamine 6G, scintillates within the wavelength
  range of 540 640 nanometers.
• This corresponds roughly to a green color around
  540 and a orange-yellow color around 640.

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Problems with the Experimental Setup

• Alignment issues
• It was extremely difficult to get the disparate
  secondary beams to line up properly.
• We were also unsure if the diffraction grating
  might not be scratched or dirty.
• We did not have a spectrometer present to better
  analyze the diffracted beam.
• Consequently, nearly all components of this
  experiment were done by eye and were, therefore,
  not very precise.

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Conclusion

• We believe that we were able to observe different
  colors from the diffracted beam.
• However, when we redirected part of the
  diffracted beam back into the cavity, we were
  unable to observe any changes in the laser.
• Therefore, we were unsure of whether or not we
  had managed to tune the laser to a particular
  wavelength.

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Suggested Changes

• Somehow enclose the setup and pump out as much
  air as possible so that a minimum of atmospheric
  scattering occurs.
• This might clean up the images we saw, not to
  mention brighten them and make them easier to
  focus.
• Use of a spectrometer of some sort would make
  distinguishing the diffracted wavelengths much
  easier.
• Finally, cleaner and possibly, less used mirrors
  might decrease the amount of blurring that
  occurred in the final image.

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Thank you!
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Further Information

• http//members.aol.com/kpublish/Laser/Dye_Laser.ht
  ml