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Interference Filter for Sub Angstrom Hydrogen Alpha Solar Scope 656.28SC0.15 Pr. For Sale

Interference Filter for Sub Angstrom Hydrogen Alpha Solar Scope 656.28SC0.15 Pr.

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Interference Filter for Sub Angstrom Hydrogen Alpha Solar Scope 656.28SC0.15 Pr.:

For the Solar Enthusiast on a Budget, a Solar Scope for under $500.

Rapid Spectral Solutions has purchased the entire inventory from Omega Optical, of overruns and excess production, as well as test runs.

For the amature astronomer who has an outgrown telescope such as a Celestron 90 m refractor that can be paired up with a 4X Barlow eyepiece, RSS can supply a set of ultra narrow thin film Fabry Perot etalons realizing a sub nanometer FWHM passband precisely positioned at Hydrogen Alpha.

The primary filter is the initial H alpha etalon positioned at 656.28 nm, or slightly longer in wavelength. This element provides a very narrow passband centered on Hydrogen Alpha, while reflecting the solar background from 550 nm to 750 nm. This filter is bonded to a high contrast rectangular passband sputtered passband coating on a fused silica substrate. That optical element is bonded on the incidence side with a MDM (Metal Dielectric Metal) etalon that has high reflectance of IR wavelengths. The combined filter has very high reflectance of the solar spectrum, and combined provides an average of OD 8++ of the solar energy coming into the telescope.


A secondary Hydrogen Alpha passband is provided to give a trimming of the first filter. Care must be taken to assure both passbands are coincidence on the Hydrogen emission spectrum peaking at 656.28 nm. This is achieved by a mechanism to gradually tilt the second etalon in respect to the first.

This assembly should give a very pure H alpha of less than 0.1 nm, centered on the Hydrogen emission. Due to the absence of absorption, the throughput of all the coatings is unity, with the exception of the MDM component which is typical 60+ % transmissive.

An additional etalon element can be added to sharpen the focus on the Ha emission. My sense is that what one is observing is the doppler shift of the rapidly moving jets, so the most significance comes from separating the slightly shifted prominence from the background.

The most important consideration is to assure the light is passing through the filters in a very parallel fashion. The optical speed at the filter location should be f 20+, and the higher the better. If this is not the case, the divergence of the rays through the filter will reduce the isolation of the Ha at the velocity in question.

Please read the accompanying paper by Mr. Jacobs and consider his recommendations on how to tilt tune the filters for maximum transmission, as well as considerations as to the eyepiece requirements.

Filer set designation from RSS:

Hydrogen Alpha sub angstrom filter # 0012: designation 656.28SC0.15 Primary, is supplied in 25mm dia rings of 5.3 and 3.5mm thickness. Set price $295.00

Additional refinement filter from RSS:

Hydrogen Alpha refinement etalon # 0013: Designation 656.28SC0.15 Secondary. (This is identical to the secondary filter of the set, and is used in a similar fashion of tilting to maximize contrast of solar structure. This item is again supplied in a 3.5mm thick ring. Unit price is $160.00

Items shipped with theoretical performance curve, as well as measured performance in Transmission and Optical Density.

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