High refractive-index IR transparent window with hard, durable and antireflective coating
AssigneeIndustrial Technology Research Institute
InventorsRung-Ywan Tsai, Fang Chuan Ho
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Abstract
A hard and durable single-layer or multilayer artireflection coating for use with a high refractive-index IR transparent substrate is provided. The coating is prepared by concurrent deposition of TiO.sub.2 and MgF.sub.2 with the reactive ion-assistance on the IR transparent substrate within a single vacuum chamber. The refractive-index of this film is adjustable by varying the relative deposition rate of the two materials (i.e. controlling the ratio of the materials) to optimize the transmittance of the incident IR irradiation. The opitical thickness of each film of the single-layer and multilayer antireflection coatings is one-quarter wavelength of the IR irradiation.
Claims8
An infrared (IR) transparent window comprising a substrate which has a refractive-index in the range of 1.88 and 4.41 at a wavelength of 1.06 um and is transmissive to infrared irradiation incident from a medium with a refractive-index n.sub.m different from the refractive-index of said substrate n.sub.s, comprising at least one layer interference coating which is deposited onto said substrate wherein
- the thickness of each said layer is one quarter of the wavelength of the IR irradiation,
- at least one layer of said coating is composed of a composite of titanium oxide (TiO.sub.2) and magnesium fluoride (MgF.sub.2), which:
- is transparent to IR irradiation in the wavelength range of 0.4 to 8 um and has a refractive-index n.sub.f less than 2.1 and greater than 1.37 at a wavelength of 1.06 um, and
- is prepared by low temperature ion-assisted coevaporation.
Dependencies are inferred from the claim text.