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Mauna Kea Observatories Y, J, H, Ks filters

Unlike optical filters in astronomy, there are much harder requirements for astronomical IR filters.
HgCdTe imaging sensor requires IR filters to have very broad blocking range from 0.4μm to 2.7μm, sometimes beyond 3μm.
Also vacuum and cryogenic environment requires to be made by monolithic substrate.
Eventually huge layers of thick interference films are necessary to achieve both requirements.

Mauna Kea Observatories (MKO) Y, J, H and Ks filter specifications were defined by Dr. Alan Tokunaga, University of Hawaii.
MKO filters are currently standard photometric system in NIR region as SDSS u, g, r, i and z-band filters in optical region.
We produce Y, J, H, Ks filters by magnetron sputtering and ion assisted deposition technology with single substrate on the basis
of MKO filter specifications, and measure the transmission curve under 77K cryogenic condition by ourselves.

figure IR Filters