Limited Edition LS75F/HR Un-Obstructed

A HR LS75F Un-obstructed filter with matchable BF at <0.6Angstroms (single stack).

During the process of R&D I have been working with new coating technologies that are very low stress and very high finesse. As you know, these coatings will be made available in the new LS152T.

One of our recent projects was the manufacture of some un-obstructed larger 75mm Hydrogen-alpha etalons. My intention was to build one and keep it for myself.

Due to batch costs, it was just as costly to make one as it was to make a few :)

As luck would have it, we have been able to produce a couple of these etalons and I have decided to make maybe 5 available. These filters are not part of our normal production and when they are gone, they are gone, we will not take any orders for more. They are a limited edition signature series filter. There is the possibility of matching 2 for a single DS system.

A little about the etalons:

Internal aperture obstructions are used to maintain the parallelism of the high reflector plates typical to an etalon.
Removing the internal obstructions, or feet, requires that the etalon plates be manufactured to the highest specification for flatness possible. Generally better than 100th wave.
In order to prevent stress to the plates (bending) after the coating process, the coating has to be done in a system that can put down a hard, accurate, dielectric at very low heat. This process is often refered to as ion assisted deposition.

In order to decrease the bandwidth, we had to improve the high reflector dielectric properties. However, in general the trade off has been that plates flat enough to take advantage of the improved coating, were too costly to produce. (higher R needed better flatness).

The coatings that we are currently introducing have higher finesse and lower bandpass. While also providing higher contrast (noise to signal and all that). We are making the blacker, black, and the brighter, bright. Sort of like HD for solar viewing..

I will discuss more about the coatings in a future blog..

The specifications are as follows:

Type: Single Etalon Front Mount Filter
Size: 75mm Un-obstructed
Bandpass: <0.6
FSR: 11 Angstroms
Blocking Filter: Price includes B1200
Adapter Plate: Not Included (POR)
Price: US$3,985.00
Availability: Limited from Stock (check your local dealer or call us)

These are subject to prior sale and we will NOT take orders after they are gone.

Each filter will be signed and dated.

We have a few other fun things coming up, so you will have to check back here to hear about them first. (How about an unobstructed 150????) ;)~