| 摘要 |
<p>Process for preparation of a CaF 2single crystal of small scattering (sic), refractive index difference and number of small angle grain boundaries involving growth of the crystal from a CaF 2material melt by cooling the melt followed by tempering, where the CaF 2crystal raw material is vaporized at no less than 1,100[deg]C under a maximum vacuum of 5.10 -4>and condensed at 500-1,280[deg]C to give a CaF 2melt which is converted to the gas phase for at least 5 hours and at 1,000-1,250[deg]C.</p> |
