Calcium fluoride crystal and method and apparatus for using the same
AssigneeCanon Kabushiki Kaisha
InventorTetsuo Kuwabara
Life of this patent
Estimating the term…
Abstract
A calcium fluoride crystal produced in accordance with a method for producing calcium fluoride crystal on the basis of refining a raw material of calcium fluoride and causing crystal growth of the refined calcium fluoride, the method including a process of raising a purity of the calcium fluoride to complement the refining, wherein a transition density in crystal is not greater than 1×105/cm2, and that dispersion of transition density inside an effective portion in crystal is in a range of ±5×104/cm2. Also disclosed is an optical element to be manufactured by use of such CaF2 crystal.
Claims17
A calcium fluoride crystal, characterized in that the calcium fluoride crystal is produced in accordance with a method for producing calcium fluoride crystal on the basis of refining a raw material of calcium fluoride and causing crystal growth of the refined calcium fluoride, the method including a process of raising a purity of the calcium fluoride to complement the refining, that a transition density in crystal is not greater than 1×105/cm2, and that dispersion of transition density inside an effective portion in crystal is in a range of ±5×104/cm2.
A method of producing calcium fluoride, comprising the steps of:
- refining a raw material of calcium fluoride;
- causing crystal growth of the refined calcium fluoride;
- removing, prior to said crystal growth step and in addition to said refining step, moisture contained in the calcium fluoride.
An apparatus for producing calcium fluoride crystal, comprising:
- a first processing unit for refining a raw material of calcium fluoride;
- a second processing unit for causing crystal growth of the calcium fluoride;
- and
- a third processing unit, separate from said first and second units, for removing moisture contained in the calcium fluoride.
Dependencies are inferred from the claim text.