| 摘要 |
A method for producing high-purity, large-volume monocrystals that are especially radiation-resistant and have low intrinsic birefringence. From a melt of crystalline raw material, with controlled cooling and solidification, a crystal is generated. As the crystalline raw material, shards and/or waste from already-grown crystals is used, and the re-used raw material 1) upon visual observation in daylight has no color; and 2) upon illumination with a white-light lamp in a darkroom a) has no or at maximum a just barely perceivable reddish and/or bluish fluorescence; and b) has no or at maximum a just barely perceivable diffuse scattering; and c) has no or only slight discrete scattering of at maximum two visually perceivable scattering centers per dm<SUP>3</SUP>. In this way, crystals can be obtained which after tempering have a BSDF value of <7x10<SUP>-7</SUP>, an RMS homogeneity after the subtraction of 36 Zernike coefficients of <15x10<SUP>-8</SUP>, an SDR-RMS value in the 111 direction of <0.2 nm/cm.
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