DIY heat sink for Herschel wedge builders

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
Post Reply
User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

DIY heat sink for Herschel wedge builders

Post by Merlin66 »

I've just received a Ceramic tile with small holes, 2-5/8" sq. x 1/2" thk., #M3156 from Surplus Shed.
I think this could make a great rear heat sink for a DIY Herschel wedge.


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
uplooker
Ohhhhhh My!
Ohhhhhh My!
Posts: 152
Joined: Thu Oct 25, 2012 12:32 pm

Re: DIY heat sink for Herschel wedge builders

Post by uplooker »

Hi Ken,
I hope you do not think me being condescending by asking, but have you built a DIY Herschel Weddge before. I would be very interested in how to go about it.
I hope you do not say "Yes, i have a comprehensive PDF file on how to do it". The last time you said something like that to me I ended up putting together a TAL 100RS PST Stage 2 and lightened my pocket by a considerable sum :P

Ian


Allcart
Im an EXPERT!
Im an EXPERT!
Posts: 496
Joined: Wed Jan 09, 2013 1:59 pm

Re: DIY heat sink for Herschel wedge builders

Post by Allcart »

Hold on to your wallet Ian, the answer is coming for sure.


Allan
User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by Merlin66 »

http://solarchat.natca.net/index.php/en ... ge-take-ii

If you can find a suitable prism wedge and use an existing 2" diagonal it's not that expensive - much much cheaper than the Baader or Lunt offerings.


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
uplooker
Ohhhhhh My!
Ohhhhhh My!
Posts: 152
Joined: Thu Oct 25, 2012 12:32 pm

Re: DIY heat sink for Herschel wedge builders

Post by uplooker »

Doh, I knew i should not have posted that reply to Ken's original - and to top it all I clicked on the link Ken posted in his reply :(

Don't worry, i am not about to dash out and persue this avenue - just yet ;)

Ken,
I do not doubt your knowledge and ingenuity, but my pocket has a distinct dislike for your posts :unsure:

Ian


colinsk

Re: DIY heat sink for Herschel wedge builders

Post by colinsk »

There is a ATM on the Cloudy Nights ATM forum that has published grinding your own 15 deg prism instructions. I don't have a link but their search engine should find it.


User avatar
DSobserver
Almost There...
Almost There...
Posts: 582
Joined: Sun Feb 19, 2012 2:36 pm
Location: FRANCE
Been thanked: 19 times

Re: DIY heat sink for Herschel wedge builders

Post by DSobserver »

any picture from your home made herschel?


User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by Merlin66 »

No,
I just used it visually on a TS102 refractor...
It performed very well.


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
User avatar
Bob Yoesle
Almost There...
Almost There...
Posts: 994
Joined: Thu Mar 08, 2012 7:24 pm
Has thanked: 540 times
Been thanked: 807 times

Re: DIY heat sink for Herschel wedge builders

Post by Bob Yoesle »

There is a ATM on the Cloudy Nights ATM forum that has published grinding your own 15 deg prism instructions.

You don't really need to use a wedge prism for a solar filter application. In fact, you can just reverse the right angle prism form any standard diagonal and do the same thing as a wedge prism:




I would blacken the side opposite from the eyepiece with a good flat black paint job...


You still need to use the ND 3 and ancillary filters AFTER THE REFLECTION to achieve a safe level of filtering. And you could incorporate any of the similar methods of venting &/or cooling to enclose the prism housing... such as a CPU heat sink, TEC, etc.

Bob B)


Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders
Goldendale Observatory
User avatar
swisswalter
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 17948
Joined: Thu Feb 06, 2014 4:28 am
Location: Switzerland
Been thanked: 1 time
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by swisswalter »

Hi Bob

thank you for the information.


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
colinsk

Re: DIY heat sink for Herschel wedge builders

Post by colinsk »

There is a ATM on the Cloudy Nights ATM forum that has published grinding your own 15 deg prism instructions.

You don't really need to use a wedge prism for a solar filter application. In fact, you can just reverse the right angle prism form any standard diagonal and do the same thing as a wedge prism:




I would blacken the side opposite from the eyepiece with a good flat black paint job...


You still need to use the ND 3 and ancillary filters AFTER THE REFLECTION to achieve a safe level of filtering. And you could incorporate any of the similar methods of venting &/or cooling to enclose the prism housing... such as a CPU heat sink, TEC, etc.

Bob B)

That is good rough math but if an error of 10% in throughput matters then make sure to study Brewster's Angle. I like the idea.


User avatar
swisswalter
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 17948
Joined: Thu Feb 06, 2014 4:28 am
Location: Switzerland
Been thanked: 1 time
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by swisswalter »

Hi Colin

that is an interesting response. How would I construct a wedge having say 10 or 20% reflection? I'm always missing light when I'm doing close ups in WL and CaK


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by Merlin66 »

Walter,
can't be done with a bare prism...the maximum reflection is around 4%.
To get any higher the front surface would have to be partially reflective coated, or use a 10/90 or 20/ 80 beamsplitter plate....


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
colinsk

Re: DIY heat sink for Herschel wedge builders

Post by colinsk »

Walter this will be an easy read for you:

http://en.wikipedia.org/wiki/Brewster's_angle

You can adjust the reflectivity and it is quite polarization dependent but Ken is right you will not increase it.


User avatar
swisswalter
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 17948
Joined: Thu Feb 06, 2014 4:28 am
Location: Switzerland
Been thanked: 1 time
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by swisswalter »

Hi Ken, Hi Colin

thank you very much. Now I have things to go after. I guess I have to start with a 10% beamsplitter


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
User avatar
marktownley
Librarian
Librarian
Posts: 42270
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20424 times
Been thanked: 10243 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by marktownley »

A 45 degree hot mirror is what you need walter - i'm having the same closeup problems in WL @ CaK too. There's a few options on Edmunds Optics site i've been considering. I'll fish out some links for you later on, got to go and get ready for work now... ;)


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by Merlin66 »

Mark,
I think you mean a Cold mirror...
http://www.edmundoptics.com/optics/opti ... rrors/1900
Problem is that they reflect 80% of visual - too much for a wedge application....
Plenty of beamsplitter plates to choose from.
http://www.edmundoptics.com/optics/beam ... tters/2035
(I use them for guiding on the spectrosocope - a "special" 4r/92t)


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
brianb11213

Re: DIY heat sink for Herschel wedge builders

Post by brianb11213 »

How would I construct a wedge having say 10 or 20% reflection? I'm always missing light when I'm doing close ups in WL and CaK
The obvious solution is to use a lighter ND filter after the wedge ...


User avatar
swisswalter
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 17948
Joined: Thu Feb 06, 2014 4:28 am
Location: Switzerland
Been thanked: 1 time
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by swisswalter »

Hi Mark, Ken and Brian

thank you very much for your help

@Brian I'm not using any ND filter at all after the wedge

@Mark I'll be lookng forward to your findings

@Ken I'll have to look into the beamsplitter plates, thank's for the link


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
User avatar
marktownley
Librarian
Librarian
Posts: 42270
Joined: Tue Oct 18, 2011 5:27 pm
Location: Brierley Hills, UK
Has thanked: 20424 times
Been thanked: 10243 times
Contact:

Re: DIY heat sink for Herschel wedge builders

Post by marktownley »

Mark,
I think you mean a Cold mirror...
http://www.edmundoptics.com/optics/opti ... rrors/1900
Problem is that they reflect 80% of visual - too much for a wedge application....


Nope, I most definitely mean a hot mirror http://www.edmundoptics.com/optics/opti ... rrors/1492 ;)

As you note cold mirrors reflect 80% of the visual, that's no good - that is what we're trying to keep.

I'm not going to use this with a wedge, I intend using instead of a wedge :evil:

Walter and I are already using shortpass/longpass filter combinations with our CaK rigs. The aim is to be able to image at several metres focal length in CaK, yet still keep the exposure shorter than 1/1000second. Imaging at 1/77s or 1/250s in CaK wavelengths at these silly focal lengths just introduces blurring as a result of the seeing. If you can image at ~1/5000th sec exposure things are much improved. You should know by now Ken we're not trying to do anything sensible :P


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
User avatar
Bob Yoesle
Almost There...
Almost There...
Posts: 994
Joined: Thu Mar 08, 2012 7:24 pm
Has thanked: 540 times
Been thanked: 807 times

Re: DIY heat sink for Herschel wedge builders

Post by Bob Yoesle »

Hi Mark,

As another source for hot mirrors (and other optics), you might be interested in Thor Labs:

http://www.thorlabs.com/navigation.cfm?guide_id=2234



In addition to Colin's link, another good tutorial on reflection / refraciton can be found here:

http://en.wikipedia.org/wiki/Fresnel_equations ;

and here:

http://www.telescope-optics.net/reflection.htm

Bob B)


Diagonally parked in a parallel universe.

Curiosity is the father of knowledge; uncertainty is the mother of wisdom.

Dark-Sky Defenders
Goldendale Observatory
Post Reply