British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

Home Forums Spectroscopy
Terms of use

Spectroscopes

6 posts / 0 new
Last post
Anthony Rodda's picture
Offline
Last seen: 1 week 4 days ago
Joined: 01/09/2014 - 14:15
Spectroscopes

Hi guys,

Just to let everyone know I've been keeping busy during these long light summer days & nights.

Photos attached of recently finished spectroscopes and asociated 'stuff'.

The fully clad Tragos in it's finished rigid body; the Paul Gerlach designed Lowspec2, mounted on-scope complete with aluminium tape coat; the new Christian Buil UVEX3, accompanied by a printed guider under testing; and, a 'calibration unit' built with a miniture circuitry that generates 400V from a PP3 9v battery, halogen flat bulb and 'different' "Relco" bulbs that I've found.

Anyway, I now have more spectroscopes than I've had clear, usable, nights in the last two months.  I'm going on my hols soon so they'll all occur then...

Regards

T

The Tragos...

The Lowspec2 on the bench...

Lowspec2 mounted...

Lowspec2 under initial tests...

UVEX3 with guider...

Calibration and 'Flat' unit...

Robin Leadbeater's picture
Offline
Last seen: 4 hours 27 min ago
Joined: 05/03/2014 - 00:50
TRAGOS limiting magnitude

Looking forward to seeing how faint the TRAGOS might go. It could potentially be a nice alternative to the modded ALPY 200 for supernova work.  (I have had some interest but copying it has been thwarted due the the unavailabity of the 200l/mm grism) What resolving power will your TRAGOS give ?

Robin

Anthony Rodda's picture
Offline
Last seen: 1 week 4 days ago
Joined: 01/09/2014 - 14:15
Tragos

Hi Robin,

It sould be around R=400 @550nm for the 23um slit.

Vadim Burwitz got 350 with a much larger pixel camera.

Here's a quick neon test run.

Regards

T

Robin Leadbeater's picture
Offline
Last seen: 4 hours 27 min ago
Joined: 05/03/2014 - 00:50
SA100 swap ?

Ah OK, a bit high for really faint objects but I guess the SA200 could be swapped for an SA100?  Are you using the PH wedge prism?

Anthony Rodda's picture
Offline
Last seen: 1 week 4 days ago
Joined: 01/09/2014 - 14:15
Wedge...

No,  I experimented with Thorlabs 4, 7 and 11 degree prisms and settled on the 6.  (I think the PH is 4 degrees?).

The "11" worked best but deviated the beam too much for my SXVH9 camera chip.  A bigger camera would probably work but I couldn't retask my Atik460.

Anyway, the easiest assembly method is to use standard eyepiece holders/spacers and just screw the four components together!  An optical train of 50mm collimating lens, prism, grating and 80mm camera lens as per Burwitz's design.  A guider at one end (Paul Gerlach's works well) and an camera connector at the other such as a T2/1.25" nosepiece type.  All that's needed is a printed tube/jacket so that the assembly can be rotated/focused at each end (to align the prism/grating with the slit and the camera).

Having built it I now know what needs putting right (!) and I'm redesigning the optics holders and guider.  I'll 'publish' the stl files in a couple of weeks.

Regards

T

Robin Leadbeater's picture
Offline
Last seen: 4 hours 27 min ago
Joined: 05/03/2014 - 00:50
Junk box

Yes the "junk box" approach is a simple alternative to 3D printing these "linear" transmission spectrograph designs. eg  

http://www.threehillsobservatory.co.uk/astro/spectroscopy_19.htm

http://www.threehillsobservatory.co.uk/astro/spectroscopy_18.htm

though I never got round to coupling them to the ALPY mirror slit guider

Claudio Balcon in Italy has recently classified a couple of faint supernovae using a similar home built collimated Star Analyser 100 setup