These $3500 are indeed a good price for two samples of such a filter. But...TheSkyBurner wrote: ↑Thu Jun 21, 2018 5:08 pmValeryy, i just asked your question about the 854.2 filter , you are looking at a cost of $3500 to prototype it for two 27mm filters and the process to make them currently has a low yield with low success rate. So they are pretty rare to make exactly where you want them and have to be sorted out very carefully after something called annealing.
“The filters are always offband deeply blue winged, and they have to be baked at 200+ celcius for several weeks to raise the red wing. It must be analyzed very regularly during the annealing process and this is the hard part”
1. What the bandwidth of these filters?
2. What the transmission curve profile? What the finesse?
3. What the transmission at the CWL?
4. What the uniformity (CWL and transmission) accross the filter aperture they can warrant ?
5. What the temperature stability of the CWL and bandwidth? If the stability is low, how can the temperature be maintained?
Without knowing these data it is quite risky to get a filter which will simply don't work.
Can you clarify what they can really offer? I believe that if the answers will be positive and such a filters can really work, especially in a Skybender tilt cell, many users can order such a working system.
854,21nm line shows real H-a like structures mixtured with a supergranulation of Ca-K - like. Overall is more impressive than H-a.
What do you, solar imagers think about such possible new direction in the solar narrowband imaging?