Rolling my own HSG thanks to santa :)

[swisswalter]

Hi Nick

great job, looking forward to your first light

[Nick]

I still need some tweaking - but this is the first image through the DIY spectroscope

capture_2014_02_26_23_54_35_0000_4_clone.png (2 MiB) Viewed 3552 times

So that DIY scope and DIY driver and DIY capture app

[swisswalter]

Hi Nick

congratulations on that first light. Why do we have here horizontal lines

[Nick]

They're caused by the dust/uneaven edges on the slit

[Nick]

Holy moly.

I've just taken the two strong yellow Hg lines..

spectrum_9_07a_Preview01twolines.png (1.76 KiB) Viewed 3528 times

20A apart and it's giving me 182 pixels.. so still unsure how accurate my measurement is - so this is native resolution crop of the two lines:

capture_2014_02_27_20_07_18_0000_1_Preview01.png (1.44 KiB) Viewed 3528 times

Wider native resolution crop:

widercrop.png (108.54 KiB) Viewed 3528 times

[swisswalter]

They're caused by the dust/uneaven edges on the slit

O.K. Nick

thank you for the explanation. so that is not really a problem

[swisswalter]

Hi Nick

it's getting very interesting. I can't commend on the lines captured, sorry

[Nick]

So.. the jury is in… in it's current 300mm form it's 0.9A, R=6410. I say current form as it's final phase one has a 2x in the design to bring the f5.6 to f11.2 to match the vixen's 910mm f11.4 (final design, in theory is 0.67A, R=8611).

Also I thought I'd take a time out.. and mention some of the lessons I've learn in doing this.

1. When I started out I thought I knew nothing, now I know I know nothing - and the void feels even bigger.

2. Design - the SIM XLS has been a very good tool for the design, both in verifying my understanding of the maths but also point out things I'd not even considered - enough to go away and research that too. When doing the design.. there's expertise out there - pick their brains, they've done it multiple times before.. because it's better than scratching your head.

3. Start simple - block of wood + bolts. I have a nickname for the alu cage in my design.. and it's not repeatable. I would strongly advise not attempting a tube cage design - I have a a 4ft high bench drill mill and I found it virtually impossible. If you're a CNC operator - start with wood.. then get fancy once you have it working..
I would say that the alu components help to keep the weight down, BUT, I would look at that AFTER the wood form is working. The more materials - the more cost, the more time needed to figure out how things will work and the more mistakes.

4. Don't under-estimate it. It may be a couple of lens and a fancy mirror thing but it's hard. Did I say it was hard?

5. Lastly .. pick one size of bolts.. I have euro M6 bolts of differing lengths.. with 4mm bolts for the small components (because they fit my adjustable slit mounting point).


Abbreviated form - Wood is good, start simple, be humble and ask people with experience because you'll learn to admit it.. they really do know more than you.

[swisswalter]

Hi Nick

moding things is fun and sometimes it is important the set it away and leave it for a couple of days/weeks ;-)

[Nick]

I forgot to say - dispersion is 0.1A/pixel.

So for now I think I will get this finalised - adding the 2x in there, fixing into the outter box, flocking/painting the inside. Finding the CoG and adding the mount point.

I think the best approach with the fixed 10um slit will be to make a metal L shape to conduct heat, fixed in with 4x4mm bolts for height adjustment. I'll use a armature arrangement with a bolt thread supplying the fine movement through the back.

Next lighting will be targeting the 400W Metal Halide/High Pressure Sodium bulbs. Then after that the big solar thing.

[swisswalter]

Hi Nick

I'm looking forward to the big solar thing. Take your time

[Nick]

Yup, I'll take it in baby steps Walter.

Ouch.. you know I said it was hard.. now I've added the PM 2x to double up the collimating lens and using the 10um fixed slit.. with a f4 imaging lens the difficulty is now obscene. I've had to modify the imaging lens FD bracket to get the back focus required!

This still needs *alot* of adjustment and alignment (reason for the other rubbish in the image) but here's a spectra - look at that line detail appearing!

capture_2014_02_28_21_50_27_0000_3_Preview01.png (641.61 KiB) Viewed 3501 times

For kicks - attached is the zero order when focusing.

[swisswalter]

Hi Nick

another step, looks interesting

[Nick]

Sorry for the slow progress.. I'm on vacation which means I'm DIYing again.. this time the bathroom floor underfloor heating, towel radiator and tiling.. so it's all locked away from the dust and muck :/

[Nick]

I managed to get the cage mounted into the box, so it's looking almost like it's final form.

[Nick]

First solar test today

Visually you can see the Ha line (slit virtually closed) - I tried looking for the CaK line but it should pop out once the dark work has done.

Things not todo - put plastic paint guard in front of the slit to check for light.. I have today's sun melted into it

Here you can see the sun on the slit and the spectrum off the grating.

IMG_2580-800x600.jpg (148.59 KiB) Viewed 3358 times

Happy that the image finding is great, the slit can take the heat easily without any problem. Happy to see the Ha line, Sodium doublet etc.

Things needed:
* scope reseated forward about 2 inches for focus changes on the 2x slit.
* Flocking and add additional walls to block light (simply too much light causes the 383L to swamp out - even with the dark pod over the top.
* put on side mount so I can mount it to the EQ6 so the slit is orientated on the drift (in the image below it's 90deg as it's sitting on the ground.
* drill support holes for the camera

[swisswalter]

Hi Nick

another great step