首页>
外国专利>
METHOD OF MAKING LARGE-VOLUME CaF2 SINGLE CRYSTALS FOR OPTICAL ELEMENTS WITH AN OPTIC AXIS PARALLEL TO THE (100)-OR (110)-CRYSTAL AXIS AND CaF2 SINGLE CRYSTAL MADE THEREBY
METHOD OF MAKING LARGE-VOLUME CaF2 SINGLE CRYSTALS FOR OPTICAL ELEMENTS WITH AN OPTIC AXIS PARALLEL TO THE (100)-OR (110)-CRYSTAL AXIS AND CaF2 SINGLE CRYSTAL MADE THEREBY
The method of making a single crystal, especially a CaF2 single crystal, includes tempering, in which the crystal is heated at 18 K/h to a temperature of 1000° C. to 1350° C. and held at this temperature for at least 65 hours with maximum temperature differences within the crystal of 0.2 K. Subsequently the crystal is cooled with a cooling rate of at maximum 0.5 K/h above a limiting temperature between 900° C. to 600° C. and then further below this limiting temperature at maximum 3 K/h. The obtained CaF2 crystals have refractive index uniformity 0.025×10−6 (RMS) in a (111)-, (100)- or (110)-direction and a stress birefringence of less than 2.5 nm/cm (PV) and/or a stress birefringence of less than 1 nm/cm (RMS) in the (100)- or (110)-direction. In the (111)-direction the stress birefringence is 0.5 nm/cm (PV) and/or the stress birefringence is 0.15 nm/cm (RMS).
展开▼
机译:制备单晶,尤其是CaF 2 Sub>单晶的方法包括回火,其中将晶体以<18 K / h的速度加热到1000°C至1350°C的温度。并在此温度下保持至少65小时,且晶体内的最大温度差小于0.2K。随后将晶体以高于900°C至600°的极限温度最大0.5 K / h的冷却速率进行冷却,然后以最大3 K / h的速度进一步低于此极限温度。所获得的CaF 2 Sub>晶体在(111)-,(100)-或(110)方向上的折射率均匀度<0.025×10 -6 Sup>(RMS),并且在(100)或(110)方向上的应力双折射小于2.5 nm / cm(PV)和/或小于1 nm / cm(RMS)。在(111)方向上,应力双折射<0.5 nm / cm(PV)和/或应力双折射<0.15 nm / cm(RMS)。
展开▼