Narrowest 393.37 ever by Apollo Lasky

[mdwmark]

That's a good company. They make high end hard coated filters. I see that they started to make amateur telescope filters(OPT has some). This must be a out of spec run from a job. The filter is spec at 393.37nm but is better at 393.44nm which is better for K-line. The way the transmission data looks ,there was a error in the run. I would say the blocking is from 200nm to 1200nm. So you better check that. You didn't say what they wanted for it. But it should make a good K-line filter.
Mark W.

[TheSkyBurner]

Yes the order was for 393.37nm but i requested it to be made off band slightly so that it can be placed specifically inside of the skybender tilt module for onband/offband control.



The filter plot is for the very first one ever made, and this is the most narrow filter they have ever manufactured in 30 years of business.

I am pretty sure Blocking is OD6 up to 1500nm,. That is what i requested.

Regardless of what anyone thinks, this is currently the best single element k-line filter on earth.

[TheSkyBurner]

the price is $1300, and there are no discounts on multiple / pooled / bulk orders.

Just accept it for what it is.

[Valery]

How uniform is this filter accross it's aperture?

What the CWL shift it has per 1degree C ?


Valery

[Valery]

The filter is spec at 393.37nm but is better at 393.44nm which is better for K-line.

Hi Mark,

Can you, please, explain why 393.44nm CWL is better than 393.37nm?

Because such a filter works in a F/10-30 cone and so, has CWL shift?


Valery

[TheSkyBurner]

valery: These are zero image shift filter's. It is unaffected by temperature up to 125c. The uniformity is astronomy grade. I do not know what other information you need. it is impenetrable to environmental conditions such as humidity and degradation.

The coating is equal across the entire 27mm surface of the filter and great care was taken to make sure of this. You will not see banding issues. Chroma technology knows what they are doing!



It requires very little tilt to change the center wavelength so the skybender allows you to put this directly on 3933.7 with maybe three threads on the micrometer tilt adjustment.

The same is going to be true for the 8542.2 filter.

it is 90%+ transmission. If this does not interest in as is now, nothing will change your mind about it. Currently It is extravagantly better than the quark, and pst and the lunt system.

This is the only way you will ever be able to tune you calcium pst modded filter, EVER.

[Bob Yoesle]

Thanks for posting this SkyBurner.

PB 0.1nm is not enough characteristic. How the sides are steep? What the skirt width? (VD)

The filter is spec at 393.37nm but is better at 393.44nm which is better for K-line. The way the transmission data looks , there was a error in the run. I would say the blocking is from 200nm to 1200nm. So you better check that. You didn't say what they wanted for it. But it should make a good K-line filter. (MW)

Mark: I contacted Dick at chroma.com and he confirmed this filter is hard coated on fused silica, 0.25 lamda, blocked OD 5 200 nm to 1200 nm. The data set he sent me also indicates the filter peaks at 393.44 nm. Price $1250 USD.

Valery: I’ve put the data (383 nm to 403 nm) into an excel spreadsheet to generate some transmission plots (300 nm and 1200 nm data points extrapolated from the quoted spec. of OD 5):

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While I don’t have comparison data for the Lunt or Coronado filters, the Baader CaK is available for comparison for the 390 nm to 400 nm transmission shown above:

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"Skirt width(s)" shown here:

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Around the 50% height of the transmission peak the width appears to be 0.13 nm (1.3 angstroms).

I went ahead and ordered the filter, and it has a 30 day refund privilege.

[marktownley]

Looking forward to seeing the results Bob, clear skies!

[TheSkyBurner]

Thanks for posting this SkyBurner.


Around the 50% height of the transmission peak the width appears to be 0.13 nm (1.3 angstroms).

I went ahead and ordered the filter, and it has a 30 day refund privilege.

You are very welcome Mr.Yoesle, your order will be superior to the prototype and will have the wings clipped even further.

The goal is 1 angstrom or less, which is going to happen.

Enjoy the unicorn.

[bart1805]

Wow! That will be very interesting, looking forward to hear and see the results. Good luck Bob.

[Bob Yoesle]

FYI, I calculated from the data supplied a FWHM of 0.12 nm, a 10% transmission width of 0.42 nm, and a 1% transmission width or 1.41 nm. These figures approximate well with a single stack Lorentzian profile which states 10% ~ 3 x FWHM, and 1% ~ 10 x FWHM.

[TheSkyBurner]

If anybody knows a crew to manufacture some 150mm objectives to be .98 strehl for this filter as a primary dedicated scope , now is the time to step up out of the shadows and help please!

Lets get this mission complete.


There are also more skybender’s on the way and i will be delivering these directly to chroma to include with the new line of filters free of charge to the first 10 people interested.


The 1 angstrom 854.2 prototype is next and i will be releasing that sometime before thanksgiving. We are all a team connected by the same web of interest. I am also working on the energy rejection systems for all to get.

Best regards to all who choose to keep this alive and well,

Thank you all from me and team Chroma
Apollo Lasky

[bart1805]

I am a bit confused now. TheSkyburner = Apollo Lasky?
Anyway: it depends on how Bob reacts when he has used the filter. In theory it is a whole lot closer to the holy grail of CaK imaging than anything else I have seen. So yes, of course I am interested!

[TheSkyBurner]

The owner of the skyburner account (Paul) is going through some personal therapy and has allowed me access to keep people updated. So for the time being, yes you now can talk to me directly.

[Valery]

A 1A filter at 854nm has no real use. Even DS of 1A at 854nm still has no real use. In both cases these filters will show less than a 2.2A filter at 393nm. The resolution at 854nm is more than twice less than at 393nm. A tiny 130mm telescope will deliver about the same resolution and more chromospheric details at 393nm than a 280mm telescope does at 854nm.

According to Giana Caussi (a leading astronomer in solar physics) only a filter 0,25A and narrower will starts to show filaments and fibrills similar to what can be seen at H-a. As far as I know such an etalon is under construction now. For this wave length one need a large telescope (for a good resolution), a very narrow etalon, a large DERF and a very sensitive and low noise camera! Otherwise this will be just a money wasting. Required a complex solution.

As for a narrow filters at 393nm. All is OK only at a first glance. These have Lorenzian profile of transmission curve and the parasitic light from the skirt of transmission curve will notably affect the contrast. The 2.2A filters available from PST telescopes have very different transmission curve and one expert I spoke with told me that such a filter likely has better contrast at 393nm line than a narrower filter with a wide skirt in transmission curve. Such a narrow Lorenzian filter has a sense if it is a double staked. Then it will have a very high contrast, but probably still not much better than two PST etalons d-stacked. More so, two PST filters #1 can produce narrower bandpass if one of them will be tilted vs other. In this case a SkyBender may help to fine tune such a system.

There are no easy and cheap solutions here at these two wave lengths if we speak about subangstrom bandwidth. Otherwise they were at the market many years already.


Valery

[bart1805]

Thanks for the clarification Apollo. And best wishes for Paul.

[TheSkyBurner]

Valery: you keep having this complex argument about how these new filter's are useless. If you are not on board then please continue to do your own thing. You have the ability to help out more than you choose for whatever reason, help is a personal choice for all. It is always graciously accepted.

However you seem to dwell on negative aspects entirely with unacceptable expectations put on everything. You are supplying people with energy rejection filters yet have not attempted to supply people with the superior narrow band elements you seem to think are just sitting on a shelf somewhere.

Either pay somebody to manufacture the stuff to your flawless specifications; like I am doing out of my own pocket with zero support from anybody or just quit trying to find flaws in everything being done here.

You ask me to mail you the filter free of charge so you can "test it out" before purchasing it and then go and post about why its not going to work before even getting the box.

Nobody will ever be able to buy the PST calcium filter ever again, and it is not even rated for 2.2 angstroms on its own.

The 1 angstrom filters are a new product to the market and unless you have something comparable to offer without additional expenses added to it, then please just accept what I am doing is the new era for amateurs.

The issue with the wings is no longer there, it will be removed from version 2 of the filter run. A single energy rejection filter will also remove those wings to negligible levels. This filter can also be used with baader planetarium astrosolar film and it will still outperform anything else on the market even at .01% transmission. It will also work in a herschel wedge as is.

I am giving people free Skybender tilt modules with this filter, so anything you are saying negative about it is just not in anybodies interest but your own.

You just do not realize how many years were spent getting to where this is at right now, with zero profit.

I have zero reason to keep doing this. Yet here i am, still trying to help people for free.


Thank you all for just being around to see this happen, because nobody else was going to do it, and dozens of people were convinced it was not possible at all.


I apologize if I sound harsh here,
but when creating a new product someone always says its not going to work and to just give up..

I especially thank Bob Yoesle for his quick understanding into what the filter is going to do for him.

[marktownley]

The 393.4 0.1 sounds very tasty Apollo, I have to agree. My mind is already thinking about it and how pre blockers can trim the wings further still.

I also hear what you're saying Valery about Ca at 854nm, but, I like playing with a Na and Mg Quark, even if they are only slightly better than WL, and for this reason 854nm is also interesting and would be something I would play with.

I often go to a bar and choose a beer that I would not normally have, and that really I know it's not going to be the drink I settle on for the night, but still I like to try it, even though it might not be to my exact taste. Different people, different ways. The important thing is that you have fun doing whatever you enjoy doing.

[Valery]

I also hear what you're saying Valery about Ca at 854nm,

All is MUCH MUCH worser and more difficult for 854nm. An etalon MUST has at least as narrow bandwidth as 0,25 (better as a DS) to start to show all the features we know well in H-a. Good IR camera is $$$$ now and this not helps either.


Valery

[Valery]

Apollo,

All your reasonings about me, you and your heroic role, your heroic efforts, PST filters low availability etc etc have nothing to do with a real subject of my post.
The real subject is that this offered filter (prototype and version 1) have no advantage against PST filter which is narrow enough for a very wide CaK line at 393nm. And I explained why - due to very different transmission curves. Again - PST is 2.2A (confirmed) filter with close to squire sides, while a single cavity filter with about 1.5A FWHN has Lorenzian transmission profile with very wide skirt. In my post I specially underlined that such a filter will be very good if double stacked, propably better than DS of PST filters.
However, DS of PST filter has an advantage - if one of the filters will be tilted, the resulting bandwidth can be significantly narrowed - this is not the case with Lorenzian filters tilting.

Unlike your former attacks at me and my DERFs, I just feel necessity to clarify the nuances of this given filter and it's difference from traditional CaK filters. Not all members here know this.

P.S.
Playing with false names is just a plain impiety to the amateur solar community. "Paul"-SkyBurner is indeed you - Apollo Lasky. I got solid evidences that "Paul"-SkyBurner exactly = Apollo Lasky.

[Bob Yoesle]

If anybody knows a crew to manufacture some 150mm objectives to be .98 strehl for this filter as a primary dedicated scope , now is the time to step up out of the shadows and help please!

Mike Jones has designed some nice scopes @ f8 and f10 3 years ago:

https://www.cloudynights.com/topic/5141 ... ke-filter/

Of course, f10 or longer is better, especially for getting closer to the narrower bandpasses...

[Valery]

If anybody knows a crew to manufacture some 150mm objectives to be .98 strehl for this filter as a primary dedicated scope , now is the time to step up out of the shadows and help please!

Mike Jones has designed some nice scopes @ f8 and f10 3 years ago:

https://www.cloudynights.com/topic/5141 ... ke-filter/

Of course, f10 or longer is better, especially for getting closer to the narrower bandpasses...

Hi Bob,

It is easy like 1-2-3 to design such an objective. 10 minutes maximum. Unfortunately, it is much more difficult to make it and then keep it optimized at this wave length. In addition only a very few individuals will really pay for such a telescope. Lucky if 5 amateurs will buy such a specialized telescope for CaK imaging.

[mdwmark]

Bob,
You should ask about the design. It is a single cavity filter. The space layer is important to how narrow the filter will be at different F#. If they designed it with a High index space ,that would be the best. With a low index you can get narrower easier but will broaden out faster in F# lower then F/30.

If they can turn on the coating machine and make 1 filter for under $1500, that cutting close on cost( i'm not sure how they can do it, with the machines they have) .

Also there no magic in correcting a doublet for K-line. If you know the design of the lens,or you could guest the design. All you will be doing in increasing the spacing of the two lens. But then it will not be corrected for anything else.
With a mica etalon at 1 Ang. The contrast jumps up , but that is with a camera , It is dim visually . With this filter, I would only use a camera .

Mark W.

[TheSkyBurner]

Guys, if this is not satisfactory for you then i am sorry, and quite saddened

We are pushing the limits of technology regarding a single piece of glass with optical coating. The goal is having the highest transmission, not the lowest half-bandwidth possible.

I can have these filters optically contacted together and or wedged with spacers to make physical faby-perot bandpass etalons; but the cost is obviously double and further R&D must be made to get it right.

These can be made into smaller size and double stacked, but then things start getting more difficult with tuning ability and vignetting.

If you are not happy with this accomplishment and offer, there is nothing more I can do to try raising your spirit.

Asking Chroma to change the specifications beyond what they are already doing for me is basically a slap in the face to the engineers.



Nobody else is doing this, I cannot emphasize that fact any more.

[TheSkyBurner]

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