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Spectrometer Mark 2

Hawksmoor

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After completing my current oil painting blitz, I spent some time today completing 'Spectrometer Mark2' in the 'clean room' or the kitchen as my wife likes to call it.  The primary reason for the redesign is my desire to use either my QHY5v or QHY5-11 as the imaging camera, without dedicating either camera to capturing spectra.  So a modular approach seemed sensible and the ability to experiment with different diffraction gratings was also an objective.  Mark1 was virtually built for 'nowt',  Mark2 has required the expenditure of a few quid mainly on purchasing an extra mounting bracket for the QHY5 (I already had one in my bag of astro bits and bobs).  I made the base from hardwood samples  handed down from my late and great mate Barry Shulver.  The tilt and turn mechanism, for holding the diffraction transmission grating, was fashioned from a camera holder and tripod obtained from everyones favourite country 'Poundland'.

I used an on-line transmission grating calculator to work out the diffraction angles for different gratings and basic trigonometry to calculate the distance between the gratings and the cameras chips to fit the first order spectrum on the chip.  Hopefully, if I've got it right , it should work ok - so watch this space for my continuing 'Chad Valley' exploits in 'Off World Spectra'!

 

Spectrometer 2 006.png

Spectrometer 2 011.png

Spectrometer 2 013.png

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andrew s

Nice job looking forward to seeing the results.

Is the grating blazed? If it is it would be worth angling the camera to center the first order. 

This is what I have done on my fiber fed low resolution spectrograph. It has extra lenses as the grating is in a collimated beam it also does not need to be attached to the telescope.

Regards Andrew

 

Very low res.jpg

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Hawksmoor
7 hours ago, andrew s said:

Nice job looking forward to seeing the results.

Is the grating blazed? If it is it would be worth angling the camera to center the first order. 

This is what I have done on my fiber fed low resolution spectrograph. It has extra lenses as the grating is in a collimated beam it also does not need to be attached to the telescope.

Regards Andrew

 

Very low res.jpg

Great looking piece of kit. Quite envious. :happy7:

I have two different gratings -100 and 500 lines- I think both are blazed and certainly the 500 line is! I have made it possible to angle the grating rather than the connection to the scope. Not sure this will work with a grating. It does with a prism.  I calculated the necessary angles and grating to imaging chip dimensions to accommodate centring the spectrum for both gratings. Have not been able to test whether this works, as have had a number of friends staying with us and did not wish to abandon them after dark (bit antisocial even for a nerd like me!).  If this rig does not work my mark3 spectrometer (in the design stage) will involve angling the camera. Thanks for the advice and sharing the image of your set up.

best regards George

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andrew s

George you need to keep the grating square to the incident light (i.e. the telescope) and then angle the camera to the first order diffraction angle as in your Mk3. 

Regards Andrew

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Hawksmoor
44 minutes ago, andrew s said:

George you need to keep the grating square to the incident light (i.e. the telescope) and then angle the camera to the first order diffraction angle as in your Mk3. 

Regards Andrew

Thanks for the information Andrew.  I did think this was likely and hence the reason why the Mk3 was in the planning stage.  Once Christmas is done and dusted I will move into the production stage. The Mk2 will work with the 100 lines grating (the camera has a reasonably large chip) but will not work with the 500 lines grating as  displacement of the first order spectrum will be too large.

Thank you for your kind advice.

Regards George

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