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Question:Substitute diffraction grating for DVD?

by msuphysicsformcb | September 12, 2020 20:16 | #24568


I'm setting up remote lab activities for pandemic-related online learning (university level). I'm thinking of having the students purchase a diffraction-grating slide such as this.

Diffraction Grating Slide-Linear 1000 Lines/mm 2x2"-Pack of 10Can this replace the shard of DVD-R in the spectrometer kit?



4 Comments

sure, you can do it. Of course the diffraction angle will be different. It looks like the dvd has 1300 lines per mm and the grating has 1000 so the dvd will have a little larger angles. I am pretty sure you can get a better price buying these in bulk rather than having students buy them individually. If you are interested, I have a bunch of stainless optical slits and I could get you a few pretty cheap. I am interested in your project. What are you thinking of having the students do? Jack

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Thanks for all the advice. This class will be online next semester due to the pandemic (I’m assuming). We have no resources or facilities to distribute the equipment so I am looking for stuff they can buy and use in their bedroom. I really doubt they have blank DVDs lying around, so buying a diffraction grating seems like the best option.

For spectroscopy, I’m thinking of both qualitative descriptions of spectra from the cell phone photos and then measuring absorption and/or fluorescence spectra from food coloring using your software. I read you can extract fluorescein from highlighters, so that might be fun.


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The Public Lab store also offers diffraction grating as an option when purchasing lego spectrometers. The grating that we carry is also 1000 lines/mm, here's where we source it from. You can order the diffraction grating with lego spectrometers (shoot us an email at kits@publiclab.org) or as an add on so that you have CDs and diffraction grating.

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I primarily use these gratings for my spectrometers (my professor supplies them for his optics class) as I find the square shape to be easy to build things around without messing with a dvd. Like the above comments say, you will lose a bit of resolution with the smaller angles, but you can adjust this with lenses or mirrors. These lines do not have the encoding the DVDs do so when you optically magnify the image in any way, they cause some distortion.

I have been working on a set of optics experiments at the university level for my thesis. I would love to hear about what you plan to do.

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