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Measured Baader dielectric and 35nm reflection spectrum

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#1 Gray

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Posted 31 July 2021 - 09:16 PM

So, I took a reference spectrum of the halogen light after calibrating from a hydrogen spectrum tube.

The intensity profile should be compared to any previous plots I displayed here.

This is my third attempt with the TO spectrometer. 

One question was asked if I could measure the reflectance from the Baader 35nm filter.  Here is that result: 

 

baader 35nm reflect.png

 

 

 

Another question I was wondering is if I bought the wrong diagonal for viewing hydrogen alpha. 

I had previously saw a statement from Baader on their site saying H-alpha is better viewed with a BBHS dielectric or coated prism. 

This afternoon I checked the same page and the statement was gone and page was updated approx. two weeks ago. 

I had also found them stating the regular dielectric had UV/IR blocking coatings, and should cut off at 740nm. 

It appears the UV light is tamed but the IR is still reflecting out past 800nm.  I don't think I need to return my diagonal for the BBHS. 

It appears the regular dielectric is reflecting around 95% close to the C line.

 

Baader dielectric diag.png

 

 

 

Here is a reference spectrum of my halogen light. 

I can use this light source within limits, but it can give me some useful information about what I have.

Figured I'd share.  

 

halogen spectrum.png


Edited by Gray, 31 July 2021 - 09:17 PM.

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#2 MalVeauX

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Posted 31 July 2021 - 09:53 PM

Interesting results Graham! What a fun tool!

 

Very best,


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#3 chemman

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Posted 01 August 2021 - 01:09 AM

Wow, that is very cool.   Nothing is better than a gang of numbers/squiggly lines!  Seriously. 

 

 Images are very cool too but for me sometimes the pretty part can seriously distract from the true nature of the data being presented.   

 

Chuck


Edited by chemman, 01 August 2021 - 01:10 AM.

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#4 Gray

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Posted 01 August 2021 - 07:13 AM

Thanks Marty & Chuck.  I still need to 3d print a light box with filter drawer and a collimator housing.  The 12mm lens kit is around $40.  My goal is to print out all these parts and hot glue them to a piece of pink insulation board.  With nothing moving, I ought to be able to get  more precise readings.  I was very curious (and nervous) on if I bought the wrong diagonal.  If the coatings were cutting at 740nm like the admin team at Baader said, I imagine intensity of the reflection at 656.3nm would be low.  Taking an intensity transmission of the reflected light from the 2 inch click stop dielectric shows otherwise.  That part is cool.  Using a 35nm filter as a sub-aperture ERF is another interest.  Looking at that plot I can see where it does reflect the unwanted light of UV and IR but I can only see out to ~860nm and these are only rough plots.  As a tool this thing is nice to have. 

 

Next things to test are the Baader TZ-4, RG 0.7x & 0.4x reducers.  There are claims of coatings for blocking unwanted light with these items too.  Also need to find a more intense light source. Maybe Xeon.  



#5 ch-viladrich

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Posted 03 August 2021 - 02:51 AM

This is quite interesting. For a check, could you measure the reflectance of a trichromic filter ?


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#6 Gray

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Posted 04 August 2021 - 08:37 AM

This is quite interesting. For a check, could you measure the reflectance of a trichromic filter ?

Yes, I just remembered I have Televue filter I can check! I forgot about it :)


Edited by Gray, 04 August 2021 - 08:55 AM.



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