Optical Coatings Japan

Daiki Sano

Hiroto Ito

Tomonori Enyo

Provide is an ultraviolet ray transmissive filter in which a crystal structure of a hafnium oxide layer is controlled to improve the light resistance of an optical interference film, and which can suppress reduction of the transmissivity in a transmission band even under long-term irradiation with ultraviolet rays. The optical interference film includes the hafnium oxide layer, and in the crystal structure of the hafnium oxide layer, spectral peak intensities from X-ray diffraction which are derived from the orthorhombic crystal structure and a tetragonal crystal structure are lower than a spectral peak intensity from X-ray diffraction which is derived from the monoclinic crystal structure.

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Gotemba, Japan

Daiki Sano