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 Calcium H (3969Å) and two Calcium K-line (3933.7Å) filtering systems. Traditionally, university research has employed the Calcium K line for studies of Calcium on the Sun. These studies have been instrumental in determining depth of the solar atmosphere. Calcium offers TWO strong absorption lines at 393.3nm and at 396.9nm, known as the K and H lines.
Researchers have previously avoided the H line for academic research, as it is very close to the Hydrogen Epsilon line. For purposes of clarity in isolating Calcium, and because imaging sensors offer similar sensitivity to the K as the H lines of Calcium, the K has to date been the target of choice in Calcium filters.
However, as the visual spectrum ends at approximately 400nm, the further we venture below this wavelength, the more difficult it is for observers to visually see the image. The H line for visual observations, is much closer to the visual spectrum and easier to see in high contrast violet colour. Some observatories have been imaging in Ca II H line, such as the Dutch Open Telescope with outstanding results.