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 Post subject: A simple DSLR spectrograph
PostPosted: Sat Jun 18, 2011 3:01 pm 
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Following my experiment with a DIY spectroscope described elsewhere: http://www.boltonastro.org.uk/Forums/viewtopic.php?f=5&t=168
I've built a spectrograph version, designed to image the spectra easily with a DSLR camera:
Attachment:
File comment: A cardboard-box spectrograph with DSLR fitted.
spectrograph.jpg
spectrograph.jpg [ 181.79 KiB | Viewed 4197 times ]


And here are a couple of spectra which I captured with it:
Attachment:
File comment: Continuous daylight spectrum showing some absorbtion lines
daylight.jpg
daylight.jpg [ 7.01 KiB | Viewed 4197 times ]

Attachment:
File comment: Line spectrum from fluorescent lamp
lamp.jpg
lamp.jpg [ 9.29 KiB | Viewed 4197 times ]


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 Post subject: Element identification from the spectrograph
PostPosted: Sat Jun 18, 2011 7:28 pm 
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I've now worked out how to use the IRIS and VisualSpec programs to convert my rainbow-stripe pictures into a diagram of intensity v. wavelength:
Attachment:
File comment: Diagram from VisualSpec plotting intensity v wavelength (in Angstroms), indicating the absorbtion lines for particular elements
daylight1.gif
daylight1.gif [ 5.58 KiB | Viewed 4194 times ]

The dips in the graph are absorbtion lines which relate to particular atoms and molecules in the Sun (and the Earth's atmosphere) - so now we can see what our Sun's made of!


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 Post subject: Re: A simple DSLR spectrograph
PostPosted: Mon Jun 20, 2011 6:51 am 
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The VisualSpec profile from my colour camera (Pentax K110D DSLR) is clearly disrupted by the pass-bands of the Red, Green & Blue filters in front of its CCD sensor, so I tried my 1004x-JG monochrome camera instead:

This is clearly much flatter across the visible region, and its much lower-resolution CCD is still good enough to show the spectral lines.

At first it seems strange to use a black & white camera on colour spectra - but remember that the diffraction process spreads the colour information into a linear dimension, so the intensity vs distance is all that's required.
In fact the VisualSpec program works on monochrome spectra anyway.


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File comment: VisualSpec's profile of daylight spectrum captured with my 1004X-JG monochrome camera
mono1.gif
mono1.gif [ 4.68 KiB | Viewed 4001 times ]
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 Post subject: Re: A simple DSLR spectrograph
PostPosted: Wed Jan 18, 2012 2:48 pm 
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Here's the previous daylight spectrum corrected for the response of my camera:
Attachment:
File comment: Daylight (Solar) spectrum after correction for camera response
daylight.png
daylight.png [ 8.04 KiB | Viewed 3969 times ]

and the re-synthesised colour spectrum:
Attachment:
File comment: Colour spectrum of the Sun synthesized in VSpec
daylight-col.jpg
daylight-col.jpg [ 16.24 KiB | Viewed 3969 times ]


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