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The new Doppler True Tuning from Lunt

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#1 Andy Lunt

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Posted 25 April 2009 - 12:56 PM

Lunt Solar Systems introduced the new Doppler True Tuning technology at the NEAF show.
This is a now a Patent Pending technology that advances the science of solar observing equipment to a new level.

The system works because the etalons used in the current Lunt designs are air spaced. These air spaced etalons are tuned to the Hydrogen-alpha line via several mechanisms.

The first is the spacing of the air gap between the high reflective surfaces of the ultra flat plates.
The distance of this spacing is generally held constant because the refractive index of the medium between the plates (air) is relatively stable at ~1.

The center wavelength can be manipulated by tilting of the etalon. This changes the angle of the light at the interface of the high reflector/air layer, having the effect of moving the center wavelength toward the blue.
Now assuming that the etalon was tuned in the normal incidence position, tilting can only shift the CWL in the one direction.

Slight changes in barometric pressure and/or a change in altitude will effect the CWL due to the change in refractive index of the spacer layer. These changes can be compensated for by tilting, provided the etalon is tuned to allow for those changes.
Taking an etalon that was tuned at 100ft to 10,000ft would not be within that range.

In the past I have manufactured sealed etalon system for space flight. These etalon systems were designed to work in a vacuum. They were manufactured as very high tuned etalons, by placing them under vacuum, the tuning lowered and we had to fine tune to ensure that at full vacuum the etalon was on band.
Additional fine tuning from there was done via heat due to the fact that the vacuum could not be adjusted.

Our technology utilizes air pressure and not vacuum.

We have enclosed the etalon system within a sealed cavity.
The sealing of the cavity is done via the collimating and refocus lens so that the etalon itself is isolated from differential pressure.
The piston applies from zero to a pressure that is equivalent to taking an etalon from -500ft to +12,000ft above sea level.
This essentially makes the etalon system altitude insensitive.
In addition the etalon can be used from -50 to +200 degrees Celsius due to the fact that the tuning can compensate for the very small changes that heat would have on the "feet" of the etalon.

I have gone into great detail regarding the compromises of tilting internal to a telescope. Only very small adjustments to the tilt can be done otherwise the etalon system will begin to suffer from the off axis rays of the collimated beam. People have noted that in internal tilt systems the CWL is very sensitive to even small adjustments of the tilt wheel.

By removing the need for tilt we have placed the etalon in the most optimized position possible.
We install a very accurately tuned etalon.
This etalon is tuned to the red side of the CWL.
Given that it is already tuned to the red, the user has the ability to shift the tune of the CWL to the Hydrogen-alpha line and then Doppler tune to the blue or back thru to the red.

Due to the fact that there is no tilt involved, the image field remains flat and precise.

Traditional tilting allows the Doppler shifting across the field in a plane perpendicular to the axis of light. The user can see a change to the image that allows for the viewing of proms or filaments.

True Doppler Tuning allows for a shift into and away from the user. Adding a 3D component to the viewing experience.
While it has minimal effect on proms due to their being at the edge, it does have an effect on filaments and active regions. While looking at a filament at the center of the Sun the user has the ability to Doppler shift from the base of the filament to the tip, following the filament thru it's structure toward you and away from you. The Tuning system provides an order of magnitude more precision to the tuning of the desired features.

We are working on designs to the LS100F and the LS100T/Na utilizing the same technology.
The LS100F will be remotely operated for those that have this filter mounted on a long FL scope and do not have 4ft long arms.

We are currently manufacturing the LS60T and the LS100T via this technology.
The LS60T is fully upgradeable to the new Pressure Tune System at any time. It does require a return to the factory.

For people who have not received their LS60T as a single system or as part of the DS package, we can upgrade at the factory at a cost of $445.

For people who have already received their LS60T, the telescope can be returned to the factory for retrofit. The cost of this service is $495. The upgrade may or may not require the replacement of the current etalon. For those who have the LS50F as part of a DS system, we do not need the LS50F back.

Due to the overwhelming response at the NEAF show, we are now estimating the upgraded system to take about 4 weeks up receipt of the telescope.

The LS60T/PT is available for sale either thru a Lunt dealer or direct. New orders have about a 2-3 month lead time. Some dealers already have them on order and we are shipping as the etalons allow.

For those still waiting on a standard LS60T we will continue to ship them as quickly as possible. The production of the LS60 line has picked up significantly over the past few weeks thanks to a change in our coating vendor, and their ability to meet our specs on a regular basis.

The LS50F as part of the DS package is still the weak link in the speed of deliveries. Being the largest non obstructed etalon we make, it is most difficult to produce. We would like to make the suggestion that if you would like to receive your LS60T before delivery of the LS50F, please contact your dealer or Lunt. We will need to be told that the future LS50F is for a DS system to ensure that we match the 50F to a 60T. This does not require a return to the factory.

#2 snowdragonusa

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Posted 25 April 2009 - 03:12 PM

Since my LS60T and LS50 for DS were matched at the factory how would the potential replacement of the LS60 etalon due to upgrading to the PT system affect the views of two unmatched etalons? Are you planning on a design to incorporate the PT system into the front mounted etalons?

#3 Tom T

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Posted 25 April 2009 - 03:34 PM

I had a chance to use a scope fitted with this at NEAF - it worked wonderfully!

#4 Andy Lunt

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Posted 25 April 2009 - 04:01 PM

Hi Adam,

The reason for the "matching" at the factory is to assure the removal of ghosts that may occur from the random orientation of 2 tiltable etalon systems.

The internal pressure tune system is not tiltable and therefore I know where the ghost is for all systems.
The front mount etalon on your existing system is already matched slightly high to compensate for the precision tune of the internal system.
Long story short. As long as I know you have a DS system I can assure the match to an existing etalon.

The external systems will be upgraded to this system eventually. We will begin with the larger systems that will benefit more from the remote operation and the field flatening effect.

The next system to be introduced with this technology will be the rear mounted ultra narrow etalon systems. Due to their very narrow FSR, they are the perfect candidate for this technology. The pressure works much the same way as heat... Just instantaneously, far more uniformly, and without power :jump:

#5 snowdragonusa

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Posted 26 April 2009 - 01:31 AM

Excellent! Thanks for the info Andy. That was just what I was looking for. I have to save up my pennies for the upgrade since I have already purchased a LS60CaKT, LS60HaT, LS50 DS, Zoom EP, and two dovetail bars (very nice by-the-way). But I think the finer tuning will come in handy once I get more accustomed to both solar imaging and visual work.

Cheers!

#6 NickH

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Posted 26 April 2009 - 04:21 PM

Rear moounted ultra narrow....

Cool..

#7 FoxK

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Posted 26 April 2009 - 05:58 PM

I couldn't pay my State taxes on time because I lost my job lol..gonna have to pay a fine next month as I restarted work...but now i'm looking at the new Ha's. I hope I get a jail cell facing somewhere towards the sun

#8 NorthWolf

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Posted 26 April 2009 - 08:16 PM

What about the LS35?, I see no mention of it.

#9 Oldfield

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Posted 27 April 2009 - 01:30 AM

excellent technology!

#10 Jim Rosenstock

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Posted 27 April 2009 - 06:12 AM

I couldn't pay my State taxes on time because I lost my job lol..gonna have to pay a fine next month as I restarted work...but now i'm looking at the new Ha's. I hope I get a jail cell facing somewhere towards the sun

:funny:

I hope it doesn't turn out that badly. :grin:

Glad to hear you're back to work....tough times don't last; tough people DO!

Cheers,

Jim

#11 Jim7728

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Posted 27 April 2009 - 06:40 AM

I looked through the LS60T/PT at NEAF and was very impressed, though I did not realize at the time this was a upgrade over the "standard" LS-60T.

What will the new price be(if any?) for the LS60T/PT version?



Nevermind.

For people who have not received their LS60T as a single system or as part of the DS package, we can upgrade at the factory at a cost of $445.



#12 NickH

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Posted 27 April 2009 - 07:05 AM

Can you give any more info at this time on the ultra narrow rear mounted setup (bandpass, size, cost, ERF requirements etc)?

#13 FoxK

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Posted 27 April 2009 - 08:25 AM

Thanks Jim :) It worked out well. I'm working on a large boat taking kids out to sea for biology class :) We pull up lobster traps, use all kinds of tools for water sampling etc. Its a blast with kids that want to be there...not so fun when they don't but even so...at least its outdoors in the sun. I'm hoping when we have LARGE groups and we have to divide them into land and boat sections, they'll let me through in some CaK sun imaging/observations.
Lunt's new technologies, and more importantly, their ability to make it all affordable really deserves alotta kudos. Hardly a day goes by now where someone isn't posting some sun images daily and it wasn't always like that. I think we're in for a real treat this new upcoming solar max

#14 Skywatchr

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Posted 04 May 2009 - 07:06 PM

Now this sounds very interesting!

Jeff

Hi Adam,

The next system to be introduced with this technology will be the rear mounted ultra narrow etalon systems. Due to their very narrow FSR, they are the perfect candidate for this technology. The pressure works much the same way as heat... Just instantaneously, far more uniformly, and without power :jump:



#15 Bill Cowles

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Posted 24 May 2009 - 08:37 PM

Here is an image of the new Doppler True Tuning device.

Bill

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