Chroma H-alpha Filter - 3nm

H-alpha filters are essential for imaging nebulae and other objects which are rich in ionized hydrogen. At 656.3nm, a narrow-band emission filter is required to separate H-alpha from the SII doublet (671.6nm and 673.1nm).

• Filters designed for use with CCD and for f/4.0 or slower
• No reflections leading to image distortions or "back reflections"
• Transmitted wavefront better than 0.25 waves/inch
• Durable sputter coatings
• Parallelism: < 30 arcsec
• Thickness: 3.0 +/-0.05mm
• Extremely durable coatings withstand humidity changes and extreme temperature fluxes and remain spectrally accurate
• in CWL and band pass adherence
• Capable of manufacturing large filters for large detectors: 50mm x 50mm, 65mm up to 76.2mm and 101.6mm square
• All filters manufactured in Vermont

Chroma manufactures the highest quality astronomy filters with durable, sputtered hard coatings using single substrates of the best glass, eliminating the need for laminations. All primary filter coatings are applied on the front surface and anti-reflection coatings on the rear surface to prevent ghosting and to maximize transmission.

Highly precise and accurate, the passbands of these filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity. All filters may be used with apertures of f/4 or smaller. They provide custom coating services for more demanding imaging applications requiring larger apertures such as f/3 or f/2. They also can provide larger sizes and unique passbands upon request.