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US 12,625,299 B2Granted
Calcium fluoride polycrystalline substance, production method of calcium fluoride particle, production method of calcium fluoride polycrystalline substance, optical element, optical system, interchangeable lens and optical device
AssigneeNikon Corporation
InventorsMariko Hirayama, Hitoshi Ishizawa, Takuro Nakamura, Yoshinobu Ezura, Yuya Yamamoto
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Abstract
A calcium fluoride polycrystalline substance, in which the internal transmittance of light having a wavelength of 550 nm per thickness of 10 mm is 98% or more.
Claims30
A calcium fluoride polycrystalline substance,
- wherein an internal transmittance of light having a wavelength of 550 nm per thickness of 10 mm is 98% or more.
A production method of a calcium fluoride particle, comprising:
- a generation step of generating a dispersion liquid containing calcium fluoride particles by reacting a calcium compound and a fluorine compound in a solution;
- a mixing step of mixing the obtained calcium fluoride particles and hydrofluoric acid which is different from the fluorine compound used in the generation step;
- and
- a separation step of separating the calcium fluoride particles and the water after adding water to the calcium fluoride particles after the mixing step.
1 more element
Dependencies are inferred from the claim text.