What does a blocking filter do?

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NightPhotographer
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What does a blocking filter do?

Post by NightPhotographer »

What is the function of the blocking filter in a solar telescope?


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robert
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Re: What does a blocking filter do?

Post by robert »

Selects a narrow band of light around the Ha line of the spectrum and rejects the multiple very narrow bands that are filtered by the etalon which can described as a comb filter. Essential part of the scope. Without it the view is swamped by many narrow bands (on either side of the Ha line) getting through, sort of harmonics or resonances of the etalon spacing.
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2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
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NightPhotographer
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Re: What does a blocking filter do?

Post by NightPhotographer »

is there a front fitted version of it? All I could find were rear fitted ones.


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Re: What does a blocking filter do?

Post by robert »

No it is in the converging light cone at the back end. The etalon has to have parallel rays to work so is on the front end
R


images and animations http://tinyurl.com/h5bgoso
2024 images https://www.flickr.com/photos/69734017@ ... 0313830045
2023 images https://www.flickr.com/photos/69734017@ ... 0304905278
2022 images https://www.flickr.com/photos/69734017@ ... 0295810277
ED80. ED100. SW200. Celestron-150mm-PST mod. C8 edge. ES127
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265
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