Artesky ERF 150 mm energy rejection filter in a metal cell (Artesky) is a front prefilter for H-alpha solar telescope systems. Dielectric coatings reduce the energy reaching the downstream optical components by reflecting radiation outside the passband. The 60 nm transmission band includes the H-alpha line.
Important: an ERF is not a complete solar filter. It must only be used as a prefilter with a complete, correctly matched H-alpha system, including the required blocking filters. Viewing the Sun through an ERF alone can cause permanent eye damage.
Mount the filter in front of the objective with the main reflective coating facing the Sun, following the manufacturer marking. The cell must fit the telescope tube securely and be protected against slipping off. The 150 mm glass diameter does not specify the cell mounting diameter.
• optical filter with a 150 mm diameter
• reduced thermal load on the downstream H-alpha system
• reflective dielectric coatings
• glass substrate with a 12 mm thickness
• metal cell for mounting in front of the objective
• filter: Artesky ERF 150 mm filter in a metal cell
• type: ERF energy rejection filter
• glass diameter: 150 mm
• glass thickness: 12 mm
• centre wavelength: 656.28 nm
• bandwidth (FWHM): 60 nm
• peak transmission: 95%
• out-of-band blocking spectral range: 200–1100 nm
• out-of-band blocking depth: OD4
• surface accuracy: λ/4
• scratch-dig surface quality: 60-40
• permitted edge chipping: below 0.2 mm
• mounting position: in front of the telescope objective
As part of a correctly matched, complete H-alpha system, the filter limits the energy reaching its downstream components.
