METHOD FOR MANUFACTURING LARGE-VOLUME CaF2 SINGLE CRYSTAL HAVING LOW SCATTERING PROPERTY AND HIGH LASER STABILITY, CRYSTAL MANUFACTURED BY THE METHOD, AND USE OF THE CRYSTAL

Japanese Patent JP2005255516

A

To provide a method for manufacturing a large-volume CaF2 single crystal having high laser stability, low scattering property, high uniformity and improved birefringence.

A CaF2 single crystal which can be tempered at elevated temperatures and has low scattering property, small refractive index difference and small angle grain boundaries is manufactured by steps of: (a) heat-treating a CaF2 material at 1,000-1,250°C for at least 5 hours; (b) vaporizing the CaF2 material at ≥1,100°C in vacuum of at most 5×10-4 mbar to produce vapor after the heat treatment in the step (a); (c) condensing the vapor at 500-1,280°C to produce a condensate; (d) producing a CaF2 melt from the condensate; (e) cooling the CaF2 melt to grow a CaF2 single crystal; and (f) then tempering the CaF2 single crystal. As the start material of CaF2 in this method, waste crystals and cuttings from a used melt can be used.

ORTMANN LARS
KANDLER JOERG
MENZEL ANDREAS
MUELLER MATTHIAS
PARTHIER LUTZ
VON DER GOENNA GORDON

JP2005043460A

September 22, 2005

February 21, 2005

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SCHOTT AG

C01B9/08; C01F11/22; C30B11/00; C30B29/12; G02B1/02; G03F1/14; G02B5/30; G03F7/20; H01L21/027; (IPC1-7): C30B29/12; G02B1/02; G03F1/14; G03F7/20; H01L21/027

JPH11240787A	1999-09-07
JPH11228292A	1999-08-24
JPS63134502A	1988-06-07
JPS6011239A	1985-01-21
JP2002255686A	2002-09-11
JP2001354494A	2001-12-25
JP2003525196A	2003-08-26

Tadashi Hamamoto
Yoshiaki Sato

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