how to build a simple spectrometer from an old CD and a cardboard box

[bluemarkus]

i just stumbled across this website from a chinese guy and he shows how to build a simple spectrometer from an old CD or DVD and a cardboard box. i just built 3 of those and they do work, you can see the spectrums of different lamps in the house, energy-saving bulbs, halogen lamps, the "old" lightbulbs, all show a different spectrum. this is highly fascinating and can be done with basically no money. just dont expect nanometer precision, but you will see the main lines clearly especially when you keep the entry-slit for the light really thin.

ok first i post helpful material, then i show my own. first a chinese guy, whose design is simple but works best for me.

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http://www.cs.cmu.edu/~zhuxj/astro/html/spectrometer.html

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then this video helps to understand what spectro-stuff is all about. its short and very illuminating.

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then finally for all who love plump women (hehe).. u can also built one out of toilet paper rolls..

i did but the chinese design works better for me

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some hints:

# use a 30° angle for the CD, it works best.

# a CD will splatter into some tiny bits+some bigger ones when broken, so do it probly in a plastic bag. use your hands.

# not all CDs/DVDs work. i had one that worked fine, and one that desintegrated without providing a useable piece. try it out !

# use gaffa tape to fixate the cd into the slit.

[bluemarkus]

so far attempts to photograph the spectrum hve failed. bu i think its possible when camera+box are solidly mounted. havent tried to use this thing with my telescope but will probly try tonight or sometime soon..

שלום - shalom

MB

[Merlin66]

The CD spectroscope is a great introduction to diffraction, but is of limited use for astronomy (other than with a slit for low resolution solar spectra).

If it gets people interested in the opportunities of spectroscopy and encourages them to build others - then it's great!

(The Star Analyser grating does provide an ideal entry point to astronomical spectroscopy and should also be considered)

[Stargazing_Cliff]

Like them things where simple to make look pretty cool i'm going to make one

[bluemarkus]

yes star analyzer with little over 100€ per unit is the ideal entry level equipment for astro.

i´m just amazed about this whole optics thing. i mean we can see that the physical laws are the same in the entire physical universe, since galaxies billions of LY away look the same when photographed and also behave the same. so just by getting a starlight spectrum we can know things about its physical reality, movement, surface temp, contained gasses etc. isnt that fascinating ? even tho we havent built telescopes big enough as to resolve even the nearest stars into a disk. we are but ants here on earth..

[Merlin66]

Prof Chris Kitchin said

" If optical spectroscopy had not been invented then fully 75% of all astronomical knowledge would be unknown today"

Other than the telescope itself, spectroscopy is the greatest astronomical tool we have.

[Stargazing_Cliff]

Mine worked i used choco wafffles box yummy and maxell cd-r that had music on it and using my samsung tocco lite mobile camera took image. pointed box at one them low watt light bulbs.

[rfdesigner]

The CD spectroscope is a great introduction to diffraction, but is of limited use for astronomy (other than with a slit for low resolution solar spectra).

If it gets people interested in the opportunities of spectroscopy and encourages them to build others - then it's great!

(The Star Analyser grating does provide an ideal entry point to astronomical spectroscopy and should also be considered)

Can you see anything of interest in our suns spectra?

(to show my kids?)

Derek

[bluemarkus]

i flattened my box now, trying to take pictures with a digital pocket camera, but to no avail. i get no sharpness into the image. DSLR or professional camera (atik, starlight etc etc) is the way to go. with a toUcam the star analyzer can already deliver humble results, but dont expect too much. apart from the balmer lines (hydrogen), many are really thin, having more resolution is necesary when u start finding other elements etc. in the spectrum. i dont think with the usual 20Angstrom resoution u normally get with toUcam u can get too good of a spectrum. the star+ rainbow trail hardly fit on the tiny chip. but at least you can check and validate the spectral class and see the most significant features and compare it to other results online. thats a start.

i´ve also seen a website where a guy bought a huge prism from a thrift store for like 15$ and put it in front of an old SLR camera and also got high-rez spectra through this. that was back in the 80s. imagine in the 80s people had no computers like today. what amateurs can do today in 1 day took a month for professionals back in time.

[nytecam]

trying to take pictures with a digital pocket camera, but to no avail. i get no sharpness into the image.

Could be 'cos the sun is at infinity and the cam autofocus locks onto the DVD/CD surface - you need manual focus on infinity as below partial solar spectrum [DVD 2nd order via handheld 300D DSLR]