DayStar's Helium D3 filter has been discontinued.

DayStar's Quantum range of solar filters are designed for professional and serious amateur applications and offer absolute precision control over wavelength transmission. The PE grade series is designed for professional research studies and applications in which precision homogeneity and on-band transmittance values across the substrate surface are required. These filters require additional quality control steps and additional fabrication and testing time.

DayStar is proud to offer the only Helium D3 Solar Filter available on the market today. Due to our recent advancements in technology which allow more precise tuning of a DayStar filter, we are finally able to capture the Helium emission line.

Discovered in the visual spectrum at 5875.61Å nearby Sodium D1 and D2 lines by Pierre Janssen in 1868 during a solar eclipse, Helium is the second most abundant element in the Universe.

Research studies in D3 in the past have focused on flare research and comparisons of correspondence of absorption in D3 with Magnetic Lines. Those studies used 'overlapograms', as He D3 filters have not been available before today.

Features visible in D3 are: Sunspot Detail, Super-Granulation, Plage, Emission in Flare Footprints, Absorption following Magnetic Lines and small prominences.

Direct Comparison He D3 to White Light - imaged with same Williams Optics 110mm APO refractor. 10/30/2010

The housing offers live LCD readout of the filter's wavelength output (accurate to 0.1Å) and red /blue wing shift buttons that can precisely tune wavelength up or down for Doppler studies. The unit operates at 12VDC for field or battery use and includes a serial port for computer control capability for on-screen display of filter readout.

PE grade filters are manufactured and qualified to a spectral uniformity in CWL (Central Wavelength) accuracy of ± 0.05 ångström. DayStar's high resolution etalon mapping equipment offers qualification certified accurate by independent testing with etalon transmission sample sizes of 5mm, 2mm or 1mm sample sizes with certification printouts available on new PE filter purchases.