ANTLIA 150mm-Glass Dual-band ND Filter Dual ERF H-Alpha & Cak/CaH Solar Neutral Density Filter Astronomical Accessory

ANTLIA 150mm-Glass Dual-band ND Filter Dual ERF H-Alpha & Cak/CaH Solar Neutral Density Filter Astronomical Accessory

Features:
Dual-band 25nm H-Alpha & CaK & CaH Line:
- It adopted the latest process design with high transmittance, high cutoff, and flat top optimization, as well as advanced coating technology to ensure the accuracy of its wavelength.
- T > 95% at H-Alpha, FWHM 25nm
- T > 90% at CaK & CaH, FWHM 25nm

Blocking: 200-1700nm:
- The ultra far design of UVIR cutoff, due to the strong solar energy, Antlia's coating range is wider, from 200-1700nm, which more blocks the solar energy in the infrared band, with OD4 (0.01%) at 300-1200nm out of band barrier design, designed for safety considerations.

1/4 λ Quartz Substrate Production:
- The Antlia Dual ERF H-Alpha/CaK/CaH Solar Filter uses quartz substrate after secondary double-sided precision polishing with 1/4λ waveform, it has better thermal stability, lower glass expansion coefficient, and a denser film layer, which is not easily affected by the environment and has a longer service life, while 1/4λ waveform ensures that, when paired with professional solar observation equipment, the impact of surface shape on image quality and wavelength on the image is minimized.

Package Included:
- 1 x ND Filter