Dark Energy Survey (DECam), WIYN Observatory (ODI), Subaru Telescope (HSC), Pan-STARRS, Discovery Channel Telescope or LSST......
Next-generation wide field telescopes now come of age. High transmission large filters with good coating uniformity are definitely one of the essential components, and help the success of survey and the great discovery.
Asahi provided the largest ever 620mm DES g, r, i, z and y filters to CTIO, Chile not by conventional ion assisted deposition but the state-of-the-art magnetron sputtering technology. Furthermore, we succeeded in developing the hardest ever large u filter. DECam 620mm u filter Asahi produced has the significantly high transmission at all positions on the clear aperture despite of the UV wavelength.