Using a laser power meter with thermopile sensor to check ERF filters

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...
etatsolarchat

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by etatsolarchat »

But the film when installed is not flat at all :?


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

http://www.baader-planetarium.com/sofif ... sung_e.htm
Doesn't have to be flat, just very very consistant....
To Quote:
TurboFilm TM - guards your optics -
This is the essence of AstroSolar ™ safety film. A highest precision, crystal clear material (not "Mylar"). It is a monomer film which we found after thoroughly testing more than 200 different film samples on our Zeiss autocollimator. This film was used in german Science Institutes as optical membrane for nuclear and particle physics experiments. The basic substrate has been further refined and homogenized by a proprietary annealing process that was developed exclusively for us. Due to these treatments Turbo Film attains perfect homogeneity and performs equal to a 1/10 wave plane parallel optical window. In fact it has the lowest wedge error of any existing optical window. TurboFilm will protect your valuable optical equipment, close telescope tubes against dust and humidity, greatly reduce air currents - all without reducing the optical quality of your telescope.


"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
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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

I was hoping to be able to replicate the power transmission testing of various filters and combinations.....
Here in Australia, no one seems to be interested in letting me hire/ borrow a Power meter.
The best so far is a quote for a new instrument - $2500!!
Well outside my budget.....bumma....


"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: Using a laser power meter with thermopile sensor to check ERF filters

Post by colinsk »

I use an older version of this for setting up my holography bench. It is not linear for frequency.

http://www.ebay.com/itm/SPER-SCIENTIFIC ... 58a02ec193


etatsolarchat

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by etatsolarchat »

Hmmm why are so many guys on this forum in Australia anyway, a lot of sun and clear sky, or the average population just more interested in astronomy?

If I could somehow move there you'd be welcome to borrow mine but the one I used goes for cheap on ebay or on ebay check out laserbee, a cheap thermopile laser power meter.. I also have one and will confirm if the readings match.

So the baader film substrate is turbofilm, that make me feel a lot better paying so much for it!


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

Thanks for the link.
http://www.ebay.ca/itm/FREE-SHIPPING-La ... 626wt_1073
Looking at the specs the limitations seem to be 5W and the spectral curve <1200nm.
This wouldn't pick up the IR out to 2500nm ?????


"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: Using a laser power meter with thermopile sensor to check ERF filters

Post by colinsk »

The Ophir Head PE50S has an expanded range.


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

Colin,
I couldn't find that thermopile on the Ophir website....
Did you mean the L50(150)-LP1-35, part #7Z027265???
(I've asked the local agent for a price)


"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
etatsolarchat

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by etatsolarchat »

3w laserbee unit read ~56mw when pointed at the sun and putting a filter on top would give relatively similar readings with the original testing. The readings were fluctuating a lot because of wind and clouds so you'd need a very calm and clear day to test but seems doable with just filters as pictured.

I don't know the response curve on the sensor but the original one I used was totally flat from 200nm to 11000nm.




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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

Thanks for the info.
You mention 56mW, but originally with the 5" scope - no filter gave 9.25W. I thought this was beyond the 3W laserbee capability??
The local supplier has come back with a price, for the sensor only of $1995 and six week delivery time!


"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
etatsolarchat

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by etatsolarchat »

56mw is just pointing the sensor at the sun, no telescope. the sensor is about 1cm2 and probably not easy to mount to a scope but I guess you could use it on a small scopes..


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by swisswalter »

Hi Eric

thank you for sharing. Interesting stuff


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 ;)
etatsolarchat

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by etatsolarchat »

Hi,


@Joe
Tempered KG glasses holds up to ~300°C and max. heat should be removed with ventilation or bigger filter area to reduce stress. At BG39 similar. Both glasses absorbs IR radiation between 700nm to 1100nm. They are not use alone exactly in focus.
(But the "UV/IR cut on KG3" is a interference filter with KG glass - reflects UV and IR 700-1200nm, over 1200nm blocks the substrat)

Oliver

So Oliver, how small of an internal ERF do you think is possible for objective? Others hear suggest no less than 1/2 the objective diameter but if they can handle 300C why not push it to the limit?


BelOptik_Oliver

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by BelOptik_Oliver »

Hi Eric,

Now general, pure absorber filters placed behind the main objective lens are possible, when the distance to focus are great. But the absorbed light energy from sun stresst the filter glass and deforms the image wavefront. Possibly crack the glass in mounting ring, if the energy enough.? Critical is only the aperture ratio.

My experience with my coated UVIR cut on KG3 filter glass (2" version) mounted 13cm before the focus of 6"F8 FH refractor for using with prominence viewer are positive. Filter glass and cone baffle keeps cool (10min), after 30min the temperature around 40°C or ~100°F (on cone baffle 46°C/~115°F). Measured with fever thermometer at 21°C air temperature and sun over horizon ~36 degree.

Sorry, I didn't experience with uncoated pure KG filter glass as single sub-aperture ERF. Only in combination with Schott RG630 (#25a) glass in front (B+W091 MRC) and naked KG3 filter (B+W 489) around 20cm befor focus in 80/910mm FH refractor for PST mod. It keeps safe cool, but the image quality with this solution is good but not perfect.


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by swisswalter »

Hi Oliver

I can basically confirm your findings. What can we do to get the perfect quality :?


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 ;)
BelOptik_Oliver

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by BelOptik_Oliver »

Hi Walter,

Perfect image quality in B+W filter solution needs wavefront error <L/4 in transmission. B+W filter min. specification is 1 Lambda or better per surface after coating process. That means if you have good luck and front+back surface has identical wavefront error in same direction, then is wavefront error in transmission smaller as the error per surface. Unfortunately this is unknown when buying - no data :(


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by swisswalter »

Hi Oliver

thank you very much. :-( that means buy and try


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 ;)
JohnM
Im an EXPERT!
Im an EXPERT!
Posts: 410
Joined: Fri Apr 20, 2012 2:06 pm

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by JohnM »

Hi Oliver

thank you very much. :-( that means buy and try

I think I'm learning that first hand. The Lumicon filter I bought is high quality, but I still can't get close to what I thought I should.


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: Using a laser power meter with thermopile sensor to check ERF filters

Post by swisswalter »

Hi John

please tell us more about the lumicon and the results. Maybe pics ;-)


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 ;)
JohnM
Im an EXPERT!
Im an EXPERT!
Posts: 410
Joined: Fri Apr 20, 2012 2:06 pm

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by JohnM »

Walter,
I've got recent posts on this 4" stage 2 from the last few days in the mod section and in the photos section. You've been replying to some :)


User avatar
daslolo
Ohhhhhh My!
Ohhhhhh My!
Posts: 62
Joined: Fri Feb 07, 2020 1:17 am
Has thanked: 4 times
Been thanked: 3 times

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by daslolo »

Maybe this could work with a heat lamp on the other end
https://www.amazon.com/dp/B07PMS5S12/re ... uEbRP309RR
81bL39AerkL._SL1500_.jpg
81bL39AerkL._SL1500_.jpg (185.4 KiB) Viewed 8801 times


PST on its way to modding heaven
Quark + Orion 120mm + beloptik
LX65 8" ACF
AndiesHandyHandies
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1444
Joined: Fri Mar 30, 2018 6:46 am
Location: Derbyshire UK
Has thanked: 3292 times
Been thanked: 1887 times

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by AndiesHandyHandies »

Hi

I purchased a cheap laser pointer thermometer off ebay fo checking temperatures in a PST mod.

Does anyone know how sensitive it is to the colour of the surface its pointed at, Black2 painted to bare aluminium?

Will it work through a lens or filter? I assume a smaller proportion of the glass and most from the Sun shining on a solid surface behind?

Cheers. Andrew.


User avatar
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

AndiesHandyHandies wrote: Wed Feb 26, 2020 9:17 am Hi

I purchased a cheap laser pointer thermometer off eBay for checking temperatures in a PST mod.

Does anyone know how sensitive it is to the colour of the surface its pointed at, Black2 painted to bare aluminium?

Will it work through a lens or filter? I assume a smaller proportion of the glass and most from the Sun shining on a solid surface behind?

Cheers. Andrew.
Hi Andrew,

I have one of these and use it all the time in the observatory for measuring the temperature of surfaces. Accuracy unknown.

For measuring the heat in the H-alpha light cone today I used an inexpensive, domestic, digital inside/outside thermometer.
The "Outdoor" sensor, on a 2m lead, was simply held on a scrap of black camping mattress foam at sharp focus.

Test of my brand new 160mm Baader D-ERF with iStar 150/10 H-alpha objective:
120F within a couple of minutes! Though I was unable to burn my hand with sun's image at focus.

Then I inserted brand new 2" Beloptik KG3 and a 2" Baader CCD, 30cm inside focus:
Temperature dropped to ~55F in 40F ambient.

Those filters must be blocking a lot of heat! Particularly when the sun reaches much higher altitudes in the summer!
Unfortunately I couldn't measure the temperature of the filters with the laser thermal "gun" due to the arrival of constant cloud.

Any thoughts on which of these filters should be placed nearest the objective?
Any point in blowing cooling air at the front filter with a small, computer fan?

P1410163 rsz.JPG
P1410163 rsz.JPG (196.82 KiB) Viewed 8745 times


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
AndiesHandyHandies
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1444
Joined: Fri Mar 30, 2018 6:46 am
Location: Derbyshire UK
Has thanked: 3292 times
Been thanked: 1887 times

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by AndiesHandyHandies »

Hi

I assume you are adding the Beloptik and the ?Red Baader CCD filter after the Baader DERF?

And measurements are without the Etalon?

After a DERF the Beloptik should only be stopping long IR.

The Red CCD should not be stopping much as I assume it leaks in the long IR like the DERF. And the 100nm pass band of the DERF is in the same red band and a bit narrower.

The Baader DERF allows 600-700nm band through from the published graph and switches back on again below 1400nm so some long IR let through.

I use the Baader 35nm filters as internal ERFs with no external DERF. People say they are the same as the DERF BUT Baaders own graphs show the DERF has a wider 100nm passband. So lets 3x more red light through.

The Baader red CCD filter shows a ?140nm passband, no graph beyond 1200nm. I think Baader are assuming the smaller 35nm and photographic filters do not need showing long IR as CCDs not officially sensitive to long IR. However Mark T reckons the long IR is absorbed by the CCD and reduces contrast. And visually I tend to agree. So the red CCD filter should make no difference after the DERF. Try just with the Beloptik?

Personally I would always use a Baader 35nm, fully illuminated, before the Etalon to reduce heat load on it, either as a stand alone ERF or in addition to a DERF. As its a dielectric filter the energy is reflected rather than absorbed as in the Red CCD so less heating of the filter so less chance of cracking it.

I reckon based on Astrograph using the 2" Baader 35nm in refractors up to 150mm as a internal ERF that the 1.25" Baader 35nm can be used as an internal ERF up to 100mm. I use it in a Vixen VMC 110mm as the internal ERF and the laser thermometer shows nothing much above ambient. I can aim it at the holder for the 35nm through the second eyepiece port on the side of the Vixen.

On my PST mod on the Vixen I put the Baader 35nm after the moved forward PST Collimator lens so that its got the collimated light on it and the refleced energy, as its a dielectric filter, goes back out spread out by passing back through the collimator lens as it came in so no dangerous hot spot from the rejected energy re-focussed.

I have used the 2" Baader 35nm as an internal ERF on my 127mm Meade triplet with no issuues. Brightish reflected light spot on the objective not cracked it yet.

So a Baader 35nm as internal ERF will reduce the red light on the etalon by 33% after a DERF. So should be better than the Beloptik and red CCD in the red.

Using the Beloptik at the back as a backup to protect your eye or expensive CCD.

Andrew.


User avatar
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

Hi Andrew,

Yes, I now have an external D-ERF followed by the 2" filters at 30cm inside focus of my 6" f/10 H-a iStar.

A Beloptik KG3 and Baader H-alpha 35nm CCD. These filters screw into a 2" x 37mm Baader Click-Lock adapter in the tailpiece.

The Beloptik KG3 is not female threaded in the front of its cell, unlike most filters, so cannot be placed second to the Baader.
Which is a shame, really, because the Baader H-a 39nm is far more obviously, surface reflective.
Making the Baader a safer option to have nearest the objective to avoid heat absorption in sustained use with a larger [6"] objective.

A new layout of PST etalon/filter stack with direct screw connection to ZWO ASI174 camera and 2" helical focuser. All nicely stiff now!
The (PST) ITF and BF filters reside inside the threaded adapter just before the camera.
The "Skywatcher" PST, etalon tuning motor uses a 16T timing pulley, 240T GT2 belt and 64mm screw [hose] clamp.
It is controlled by a HitechAstro DC focuser controller.

P1410182 rsz.JPG
P1410182 rsz.JPG (230.02 KiB) Viewed 6177 times


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
AndiesHandyHandies
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1444
Joined: Fri Mar 30, 2018 6:46 am
Location: Derbyshire UK
Has thanked: 3292 times
Been thanked: 1887 times

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by AndiesHandyHandies »

Hi

In your reply to my question about the laser pointed remote thermometer you said

2" Baader CCD

I assume you meant a Red CCD filter but from your last comment is it in fact the Baader 35nm dielectric filter, you said 39mm which I assume is a typo.

Yes its a shame the beloptik is not front threaded.

You could swap the filter glasses over in the two holders if they are the same size or move the Beloptik to a cheap coloured filter holder? As it would be best with the 35nm first as you say.

Cheers. Andrew.


User avatar
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

Thanks Andrew,

Rewrite: I have just read the earlier posts from 2013. Where Oliver at Beloptik discusses a KG3 temperature tolerance of 300C!
Which makes my 120F measurement at focus behind the D-ERF look like rather, small beer. My filters are also well within focus.
Hopefully these filters will not be remotely as stressed as trying to use them as a D-ERF in their own right.
There were no filters, at all, to protect my PST etalon after the sub diameter, internal D-ERF.

The obviously higher, visual reflectivity of the Baader H-a 35nm may have no relevance at all in the red light following the full aperture D-ERF.
I may need to make some large holes in my main tube so I can monitor filter temperature with a "fever" gun. [To give it its topical name.]
If need be, I can then add a cooling fan to the "ventilation" hole for those long, hot, summer days of imaging at 55N, later in the year. ;)
Last edited by Rusted on Sat Feb 29, 2020 7:07 am, edited 1 time in total.


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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: Using a laser power meter with thermopile sensor to check ERF filters

Post by Merlin66 »

Ok
Can we get a little more rigor in the testing and reporting.
Use one filter at a time and record the results, then move on to adding one filter and recording results , repeat. Etc.


"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
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

Merlin66 wrote: Sat Feb 29, 2020 7:07 am Ok
Can we get a little more rigor in the testing and reporting.
Use one filter at a time and record the results, then move on to adding one filter and recording results , repeat. Etc.
Point taken. :D

If only it were possible in the present, seemingly endless, heavily clouded, with showers, weather regime..

If it were not for the high speed of my ASI174 there would be no chance [at all] to capture a cloud-free sun!

2000 frames at 320 & 390fps, for 800x600 and 640x480, 1-2ms, in 5-6 seconds, is only just, fast enough!

Three heat bands running for hours at 80F and I'm still struggling to stay ahead of the dew point using an additional hairdrier! ;)

P1410185 rsz 500.JPG
P1410185 rsz 500.JPG (37.73 KiB) Viewed 6147 times


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
AndiesHandyHandies
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1444
Joined: Fri Mar 30, 2018 6:46 am
Location: Derbyshire UK
Has thanked: 3292 times
Been thanked: 1887 times

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by AndiesHandyHandies »

Hi

The Baader 35nm is reducing heat on the etalon by 33%. And the Beloptik stopping long IR. Providing more protection for the expensive blocking filter.

You can unscrew the retaining ring in the Beloptik and then screw the Baader 35nm in and it will act as the retaining ring and they are then in the best order.

Andrew.


User avatar
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

Or, I could swap the filters over between cells.
I just need to find my screw-adjusting dividers to loosen the retaining rings.


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
User avatar
Rusted
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 1738
Joined: Fri Jan 19, 2018 11:00 am
Location: Central Denmark
Has thanked: 8016 times
Been thanked: 1938 times
Contact:

Re: Using a laser power meter with thermopile sensor to check ERF filters

Post by Rusted »

AndiesHandyHandies wrote: Sat Feb 29, 2020 2:55 pm Hi

The Baader 35nm is reducing heat on the etalon by 33%. And the Beloptik stopping long IR. Providing more protection for the expensive blocking filter.

You can unscrew the retaining ring in the Beloptik and then screw the Baader 35nm in and it will act as the retaining ring and they are then in the best order.

Andrew.
I tried swapping around various filter mounts but the KG3 glass was much too thick.
So I used your clever idea of stacking the Baader 35nm H-a in front after removing the KG3 front locking ring.
I even remembered to wear disposable nitrile gloves to avoid marking the filters with fingerprints.
Now I just have to remember not to unscrew them, in the usual manner, or I might drop the KG3 glass! :oops:

Thanks for the useful suggestion. ;)


http://fullerscopes.blogspot.dk/

H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
Post Reply