The Lowspec spectrometer

[Thalestris24]

After much fiddling and fettling, finally managed to get an image on the Atik 383l+. Not near to getting an actual spectrum yet - well, maybe not that far off... This was done using a 405nm laser pen via a 500mm Mirror lens. Just with my practice slit, and not yet with a proper grating, either. I did a mock-up of one using a mirror with a transmission grating in front . That probable won't work in the way I sort of hoped ha ha. Still, to get any kind of  image via the lens, slit, mirrors and internal lenses is encouraging. I was able to shift the position of the image using the micrometer. I also tried adjusting the camera focus using the knurled knob on the focuser mechanism. I'm a terrible judge of focus these days...

Anyway, here's one of the images I captured via SharpCap (reduced to 30%):

It's very rough and (laser) speckly, and reflects my rather poor quality diy slit. I think my next step will be to install the proper Ovio slit. I also need to glue the pla T-adapters in place in their respective holes. I added a qhy5l-iim guide scope yesterday and that works fine. Oh, I used a 30mm dia lens for the camera and which appears to have a fl of 100mm. Not sure where it came from - have lost track of all the lenses! It's not on the list of lenses I got from Surplus Shed. Maybe it's one of the 6 x 30 finder lenses. I thought they had a fl of 125 mm but perhaps that changes with the way it's being used? Oh well, it seems to do the job.

Louise

 

 

[Merlin66]

Louise,

Looking good....

I think the time has come to re-assemble with all the correct optics/ grating and actually see the results of your hard work.

Almost there........

Ken

 

Edited December 6, 2019 by Merlin66

[Thalestris24]

11 minutes ago, Merlin66 said:

Louise,

Looking good....

I think the time has come to re-assemble with all the correct optics/ grating and actually see the results of your hard work.

Almost there........

Ken

 

Indeed! I'm just waiting for some M3 machine screws - I somehow managed to not order enough before, and I need some to be able to fasten the grating holder to the case. Everything is looking good at the moment. The question is: "Will it all work together and well enough to give a decent spectrum?" Time will tell! I have some neon bulbs and was thinking of using one to calibrate with. I've yet to try one out. Also might make some sort of slit illuminator with a led.

Louise

[Merlin66]

I'd recommend starting the "testing" on the bench with a fluoro lamp illuminating the slit.

 

[Thalestris24]

4 minutes ago, Merlin66 said:

I'd recommend starting the "testing" on the bench with a fluoro lamp illuminating the slit.

 

What's a fluoro lamp? You mean one of these ?

Louise

 

[Merlin66]

Louise,

Yeah, that's what I use....

You can also get hand held portable version.

https://www.ebay.com.au/itm/12V-Fluoro-Work-Light-Accessories/163334673770

Edited December 7, 2019 by Merlin66

[Merlin66]

Louise,

Any progress???

 

[Thalestris24]

9 minutes ago, Merlin66 said:

Louise,

Any progress???

 

A little... I've been struggling a bit cos I can't see what I'm doing (cataracts ), changing from one pair of glasses to t'other all the time, and also keep dropping things (unknown reason, but have been losing my grip - literally! ). It hasn't helped that the days have been gloomy, not to mention short, of course. But I've managed to get a few things done today. I glued the camera T2 fitting in place. Still to do the lens T2. Really, I just need to put in the Ovio slit,  Thorlabs 600 line grating, and maybe the proper mirrors. I'm not convinced about the mention of pla letting through IR. The case is pretty thick. At the worst case could coat it with something. Yesterday I was doing 30 sec exposures using the Atik and didn't notice any problems. The Atik 383l+ itself is a bit heavy and I currently have everything mounted on a dovetail with an Al bar extension to support the Atik. I'm just reprinting part of a bracket to use to help support the Atik. I'll post a photo when it's all done - well, if it works! Anyway, I'll just have to see how that setup goes. Can always change things if I have to. I wish I had a workshop and bench like Rockmover has in his video! Instead, I have to make do with my dusty sitting room and my lap! Oh well.

Cheers

Louise

[Merlin66]

Louise,

Under the circumstances you're doing well......

You'll be reinvigorated when you see that first Fluoro spectrum appear!!!

Ken

 

[Thalestris24]

Just now, Merlin66 said:

Louise,

Under the circumstances you're doing well......

You'll be reinvigorated when you see that first Fluoro spectrum appear!!!

Ken

 

I'm not sure one can buy cfl bulbs anymore - most places don't seem to stock them anymore (none in Tesco and probably not in Lidl either). Presumably because of the expectation that the EU was going to ban them. I have one in my bedroom and might be able to do some testing in there. I'll sort something out  

Louise

[Merlin66]

Hmmmm,

I thought it was the other way round.

They were going to ban the old incandescent lamps and replace them with the low energy fluoro lamps......

That was back in 2007.

Ken

 

[Thalestris24]

3 minutes ago, Merlin66 said:

Hmmmm,

I thought it was the other way round.

They were going to ban the old incandescent lamps and replace them with the low energy fluoro lamps......

That was back in 2007.

Ken

 

Yes, re incandescent lamps, but I think they don't like the mercury in fluorescent lamps, and consumers apparently don't like them anyway.

Louise

[ejp1684]

1 hour ago, Thalestris24 said:

I'm not convinced about the mention of pla letting through IR.

I've found it does let through IR so I've covered mine with aluminium foil. I had some roof flashing so used that on the main sections and kitchen foil on awkward sections. If kitchen foil was good enough for the Pioneer spacecraft, it's good enough for me!

Eric.

[Thalestris24]

5 minutes ago, ejp1684 said:

I've found it does let through IR so I've covered mine with aluminium foil. I had some roof flashing so used that on the main sections and kitchen foil on awkward sections. If kitchen foil was good enough for the Pioneer spacecraft, it's good enough for me!

Eric.

What, under starlight?

Louise

[saac]

5 minutes ago, ejp1684 said:

I've found it does let through IR so I've covered mine with aluminium foil. I had some roof flashing so used that on the main sections and kitchen foil on awkward sections. If kitchen foil was good enough for the Pioneer spacecraft, it's good enough for me!

Eric.

Wait, I'm confused, not difficult, won't IR be present in the light from the target anyway?  is this background IR we are talking about and is it really significant to cause a high SN ratio?

Jim 

[saac]

2 minutes ago, Thalestris24 said:

What, under starlight?

Louise

That's what I'm confused about ?

Jim 

[saac]

Hey Louise, I now have my grating (Thor Lab) , OVIO slit (some french company)  and lenses (Surplus Shed). The lenses from Surplus shed were nearest match to those specified so I'm not overly confident they will match well - worth a go though.  I'm printing out all the internal components now; just done the grating holder assembly (lots of fettleing required) and now the Ovio slit holder.  Re the CFC lamps you can still get them on Amazon surprisingly , like you I thought they had all but disappeared now - nobody wanted them because of the warm up period.    So,  I'm still good bit behind you, may not get it done this side of Christmas, but I'm following your progress with great interest and making notes. Good luck with your test phase. 

Jim 

[Thalestris24]

8 minutes ago, saac said:

Hey Louise, I now have my grating (Thor Lab) , OVIO slit (some french company)  and lenses (Surplus Shed). The lenses from Surplus shed were nearest match to those specified so I'm not overly confident they will match well - worth a go though.  I'm printing out all the internal components now; just done the grating holder assembly (lots of fettleing required) and now the Ovio slit holder.  Re the CFC lamps you can still get them on Amazon surprisingly , like you I thought they had all but disappeared now - nobody wanted them because of the warm up period.    So,  I'm still good bit behind you, may not get it done this side of Christmas, but I'm following your progress with great interest and making notes. Good luck with your test phase. 

Jim 

Hi Jim

I've currently fitted a 121mm fl, 26mm dia doublet from surplus shed for the collimator and a 100mm fl, 31mm dia doublet for the camera lens (think it must have come from my 2" ep but not sure... Still not put the Ovio slit in - will aim to do that tomorrow I don't think I'll worry about IR passing through for now. If there seems to be a problem I have some blackboard black spray paint - might be worth trying, though I don't have any infra red data on it. Oh, I never got my slit holder locking ring to screw in but I can push/click it in, so think that will do . Did you get the 600 lpm grating? You have to be careful with Thorlabs ordering - first time round I inadvertently ordered an IR version - tut! But they kindly sent me a replacement visible light one together with another box of lab snacks!

No rush - we can take our time. The stars will still be there

Louise

[Thalestris24]

I've been trying to fit the Ovio slit into the printed holder (17_ovio_holder) but having difficulties... I've printed this thing out several times before and again today. The trouble today is the slit won't fit flat in the holder. It seems to be due to the 'lip' which goes around the bottom of the inner rim. The holder seems to otherwise fit ok. Anyone else had this problem or is it just me? Is it something to do with my Ender 3 pro or the slicing? Any help or suggestions gratefully received!

Here's a pic:

 

Louise

[ejp1684]

I've had to do 'post processing work' on just about every component of LOWSPEC, ie take a file to them to make them fit. I'm sure I had to do this to make OVIO sit nicely.

Eric.

[Thalestris24]

Just now, ejp1684 said:

I've had to do 'post processing work' on just about every component of LOWSPEC, ie take a file to them to make them fit. I'm sure I had to do this to make OVIO sit nicely.

Eric.

Oh ok - not just me, then! Do yo remember if you had the lip at the bottom? I don't see any need for it unless the slit is supposed to sit atop it??I'm also trying to file it...

Thanks

Louise

[ejp1684]

I've had a look at a previous print of the ovio holder, and it looks as if the Ovio is supposed to sit on the lip. I didn't file any of the lip away, so the ovio sits on it and the threaded ring keeps it flat against the lip.

The lip makes sense, as it keeps the silvered surface of the Ovio from contacting with the surface of the holder.

Eric.

[Thalestris24]

12 minutes ago, ejp1684 said:

I've had a look at a previous print of the ovio holder, and it looks as if the Ovio is supposed to sit on the lip. I didn't file any of the lip away, so the ovio sits on it and the threaded ring keeps it flat against the lip.

The lip makes sense, as it keeps the silvered surface of the Ovio from contacting with the surface of the holder.

Eric.

Oh well, I've got it in as best I can... Of course, it's in the opposite position to what it's supposed to be, tut! (the 20um slit is numbered 150 ha ha) but I've had enough of it now so it can stay like that! I'll give it a try out when I can.

Louise

[Thalestris24]

Picked up some street lamps via the guide cam - quite bright and fairly well focused! Also got something spectroscopic-looking via the Atik too . A bit blurry but that's not surprising. I'm not sure how well focused the Atik and collimator are. I'll obviously have to try using the proper grating. I'll post some pics of what I did get later.

Louise

[Thalestris24]

Here's one of the Streetlight images from earlier. They are yellow but I don't think they are sodium since viewing them through a SA100 shows a rainbow spectrum though mostly yellow and red.

(reminder: it's a non-blazed 500l/mm holographic transmission grating taped to a mirror ). Taken through a closed window, with blinding floodlights and under the Moon! You can see a spectrum by this means but can't expect it to be clear and sharp! When the floodlights opposite go out (usually around 10:00 - 10:30pm) I'll try again.

Louise

ps Above was done using the widest slit - 700um, as that was easy to see! I couldn't see a slit at all when one of the small ones was selected. 

Edited December 9, 2019 by Thalestris24