Solarscope Hydrogen Alpha Telescope and Filter Safety
At the front of the solar filter is the energy rejection filter ( ERF ).
The ERF is used together with optical blocking elements to suppress ultra
violet and infra-red wavelengths. These optics also control the brightness
of the final image. The combined blocking effect of these elements in the UV
and IR are shown below, in the Perkin Elmer Lambda 900 spectrophotometer
transmission plot. The transmission peak at 600 - 700nm is part of the
visible spectrum and contains the H-alpha spectral line at 656.28nm.
This is an important emission line used for solar observation as the Sun’s
surface layer contains a high proportion of Hydrogen.
Final suppression of unwanted light and transmission of a single narrow H-alpha spectral line is achieved by the addition of the etalon / secondary filter combination. This is an ultra narrow line width 0.7 Ångstrom bandpass filter, consisting of a precisely tuned, air spaced Fabry-Perot etalon, used in series with a secondary multi-cavity interference blocking filter. The latter blocks all transmission peaks of the Fabry-Perot etalon, except for a single ultra narrow spectral line centered at 656.28nm, the H-alpha wavelength. The transmission characteristics of the etalon and secondary blocking filter are too narrow to be resolved and shown meaningfully on the above plot.
The dedicated, compact and thermally stable telescope ‘Solarview 50’ and the ‘Solar filter systems’ use 50mm aperture Fabry-Perot etalons. Both products are also available as enhanced contrast double etalon filters. Single filters can be converted into double units, as required. The Solar filter is mounted onto the front of the user’s telescope with the use of an adapter plate, providing safe observation of entire solar disc, in hydrogen-alpha light. The filter 0.7 angstrom transmission bandwidth provides superb views of prominences and surface detail such as granulation, filaments, flares, etc.
Final suppression of unwanted light and transmission of a single narrow H-alpha spectral line is achieved by the addition of the etalon / secondary filter combination. This is an ultra narrow line width 0.7 Ångstrom bandpass filter, consisting of a precisely tuned, air spaced Fabry-Perot etalon, used in series with a secondary multi-cavity interference blocking filter. The latter blocks all transmission peaks of the Fabry-Perot etalon, except for a single ultra narrow spectral line centered at 656.28nm, the H-alpha wavelength. The transmission characteristics of the etalon and secondary blocking filter are too narrow to be resolved and shown meaningfully on the above plot.
The dedicated, compact and thermally stable telescope ‘Solarview 50’ and the ‘Solar filter systems’ use 50mm aperture Fabry-Perot etalons. Both products are also available as enhanced contrast double etalon filters. Single filters can be converted into double units, as required. The Solar filter is mounted onto the front of the user’s telescope with the use of an adapter plate, providing safe observation of entire solar disc, in hydrogen-alpha light. The filter 0.7 angstrom transmission bandwidth provides superb views of prominences and surface detail such as granulation, filaments, flares, etc.