Finally got the pick off mirror in the right position to allow imaging with the ToUcam. With a 100mm collimator/ camera and a narrow slit ( more on that in a moment!) managed to get my first images of the solar spectrum to check resolution etc.
The results exceeded all my expectations!!!! I'm actually getting 0.43 Angstoms/ pixel resolution!!!!!! I had to download the detailed specta from Kitt Peak to find a comparison. The Na lines are wide apart and you can see the Fe line between them. All this without even connecting it to the telescope, just bright sunlight into the slit.
The attached photo is a stacked 16 images, no corrections with the Kitt Peak comparison spectra just below. The Mg bands etc.
My effort with razor blades for the slit was so-so, it needs to be quite far into the 1 1/4 adaptor so the size of the "body" is limited to about 29mm diam. Need to find a better solution before the next trials.
Nice spectral lines Merlin. Can you explain a bit more what we're looking at? Along the horizontal is obviously wavelength as apparent from the colour change from left-to-right. But what is the quantity that is changing along the vertical?
Steve, they are the spectral lines of the various elements stated.
By taking readings at diff times, they can tell if it's red or blue shifted too. I think that's how it's done. L.
ps. all the same elements on earth. eg; sodium/mercury vapour lamps etc
They set up a control lights spectrum on one side/edge of the plate & the object/stars spectrum on the other & compare them.
Steve, The full spectrum looks like a rainbow and the colours relate to elements. Wherever the vertical lines cross the spectrum tells you what chemicals/elements are in the star/object.
Here it is stacked along the vertical, i.e., just blurred completely in the vertical direction, plus a final level adjustment to improve contrast. (hope you don't mind me playing around with your pic...) You could get more detail by stacking with realignment.
Yeh the vertical lines are from the razor blade. I can get you a mechanical variable slit mechanisim that you can pull apart and fit to get a cleaner edge, I have to look for it though.
I always throw these things out just before someone needs them...
No actually I have an actual slit wheel with a set of 8 or so laser cut slits in it at different widths. That's much easier to use. I'll put it in the "for Ken" box.
No actually I have an actual slit wheel with a set of 8 or so laser cut slits in it at different widths. That's much easier to use. I'll put it in the "for Ken" box.
Gee thanks Stu, but what do I want it for? Merlin is the one doing the Spectral Imaging
One of the (now deceased) members at out Ballarat Society had a Spectrum Analysis EP and it was magic. Bung it in and see what each star is made of! If I remember, he paid a massive amount of dollars for it 20 years ago.
Janoskiss, that was a tremendous improvement, many thanks! I'm using PSP7 for other stuff ( like painting Spitfire models for FS!) but never saw the blurr "vertical" will have a look in a minute.
Any help you can give me Stu, would be appreciated VERY much!!!
I use the Gimp mostly, but PS should be the same. There is no "blur vertical" as such, I just go to Filters->Blur->Gaussian Blur. Set "Vertical" to something very large, say 1000 (this effectively averages all pixels values along the vertical) and "Horizontal" to 0 (no blurring along horizontal). Motion blur is another good one, and you can adjust the blur angle if the spectral lines are not quite vertical.
Actually I just tried it and motion blur gives sharper lines in the Gimp. Needs to be applied repeatedly (max length is 256 pixels) until all detail along the vertical is completely blurred out. See attached pic.
Edit: replaced pic. First one wasn't cropped properly before blurring and some of the comparison inset got mixed in.
Wow Merlin this is fantastic stuff, real astro science. Can't wait to see your results on stars. This thread is also a microcosm of the IIS cooperative spirit - already we have Steve providing a means to clean up the spectra and Stu digging out of his kit bag for a better "razors edge". Great stuff guys
After the initial trials I ended up re-doing the pick off mirror support ( the most fiddly bit of building this design... believe me!) I then found that the grating had to be inclined by about 1.5 degree to "throw" the return beam onto position (ToUcam/ 6mm Mono eyepiece). Now done and everything back to working order. Have re-done a couple of slits ( If Stu can me help it would be great!!!!!) one very narrow ( 10-15 micron?) and one wider ( 0.5/ 0.7mm) for stellar work.
Won't get the chance to try it before the weekend, but keep you posted.
I'll try and drop of the stuff before I go to perth on friday.
Hey I asked around about the grazing angle! The grazing angle is the angle at which the grating is the most efficient, ie. reflects the most light. At the moment you are using a grating that has a blazing angle at 240~280nm I think (in the UV range anyway). So if you find the you don't get enough light in the red, then you can change the grating to one that has the same number of lines per millimeter (resolution) but has a higher blazing angle. The exact type that I happened to have accidentially not thrown out this week.
Unfortunately I don't know what to do about the resolution problem you are having. I found the old dual sided 600/1800 lines/mm grating I was looking for a month ago but they are to big to fit in your spectroscope and they are quite badly scratched. I think one of them was even drawn on by someone.
Merlin, I've been following this discussion with real interest. Unfortunately I'm a bit lost as to how your spectroscope works/is put together. Would you be able to include a bit of a diagram or a link to a webpage that shows what it is you're doing and a bit of an explanation on how it works.
L.
. Can you use it also to examin the spectral lines of stars and DSOs?
I think one of them was even drawn on by someone. 
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