About observing the mewcury spectrum with a Fabry-Perot interferometer

[luisgml_2000]

[SOLVED] About observing the mewcury spectrum with a Fabry-Perot interferometer

Hello!

I've been trying to observe the interference fringe pattern from a mercury discharge tube, but the pattern has not already shown up. I simply don't understand what I'm doing wrong.

The first thing I did was to align both mirrors with a laser. With that source I saw the fringes, but after replacing the source the pattern gets lost. I've tried putting convergent lenses between the interferometer and the source but it doesn't help at all.

 

[Jhero]

Hello,

Thank you for reaching out with your question. It sounds like you are on the right track with aligning the mirrors using a laser source. However, there are a few other factors that may be affecting your observation of the interference fringe pattern from the mercury discharge tube.

First, make sure that the mercury discharge tube is properly positioned and aligned with the interferometer. Any small misalignments can greatly affect the interference pattern. Additionally, check the intensity of the light coming from the mercury discharge tube. If it is too dim, the interference pattern may not be visible. You can try adjusting the voltage or current going to the tube to increase the intensity.

Another factor to consider is the spacing between the mirrors of the interferometer. This distance, also known as the "air gap," determines the resolution of the instrument. If the air gap is too small, the fringes may be too close together to be distinguishable. If it is too large, the fringes may be too far apart to be observable. Make sure to adjust the air gap to the appropriate distance for your specific experiment.

Finally, the wavelength of the light being emitted from the mercury discharge tube may also affect the interference pattern. The Fabry-Perot interferometer is most sensitive to certain wavelengths, also known as the "transmission peaks." These wavelengths can be calculated using the equation:

λ = 2d/√(m)

Where λ is the wavelength, d is the spacing between the mirrors, and m is the order of the interference fringe. Make sure that the wavelength of the light from the mercury discharge tube falls within the transmission peaks of the interferometer.

I hope these tips will help you successfully observe the interference fringe pattern from the mercury discharge tube. Keep experimenting and don't hesitate to reach out with any further questions. Happy observing!