Multi-Beam Optical Afterheater for Laser Heated Pedestal Growth
OwnerEugene Standifer, Gisele Maxwellinventors
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Abstract
A post-growth optical afterheater system includes an appropriate choice of optical heat source for the single crystal material to be heated, a power adjustment module for controlling the optical power heating the crystal, and suitable focusing optics to focus the heating beam onto the crystal. The heat source may be a laser of appropriate wavelength or an incoherent source of sufficient power. In one embodiment, the power adjustment module is an optical attenuator, either of crossed-polarizer design or of intersecting wire grids. The focusing optics may be refractive, reflective, or catadioptric, depending on factors such as diameter, cost target, and space available in the crystal growth apparatus.
Claims21
A laser heated pedestal growth optical afterheater system for growing a single crystal rod, comprising:
- a device for growing a single crystal rod from a feed material via laser heated pedestal growth;
- a laser that generates a first laser beam;
- and
- a concentric bifocal mirror positioned optically downstream of the first laser beam, the first laser beam transformed into a molten zone beam and an afterheater beam, the bifocal mirror including a first circularly symmetric focusing zone and a second circularly symmetric focusing zone, the first focusing zone directing the molten zone beam to melt the feed material at a molten zone interface to the single crystal rod, and the second focusing zone directing the afterheater beam to an afterheater region of the single crystal rod.
A laser heated pedestal growth optical afterheater system for growing a single crystal rod, comprising:
- a device for growing a single crystal rod from a feed material via laser heated pedestal growth;
- a laser that generates a first laser beam;
- a first mirror that deflects a central portion of the first laser beam to thereby form a circular afterheater beam and an annular molten zone beam;
- a second mirror that optically realigns the molten zone beam and the afterheater beam;
- a first optical attenuator and zoom beam expander positioned between the first and second mirrors in an optical path of the afterheater beam;
- a second optical attenuator positioned between the first and second mirrors in an optical path of the molten zone beam;
- a reflective axicon that transforms the realigned molten zone beam and afterheater beam into a substantially annular beam;
- an elliptical flat mirror with a central hole, the feed material and/or single crystal rod positioned through the central hole, the elliptical flat mirror directing the substantially annular beam to a direction parallel to the crystal growth axis of the single crystal rod;
- and
- a concentric bifocal mirror including a first circularly symmetric paraboloid mirror and a second circularly symmetric paraboloid mirror, the first paraboloid mirror directing the molten zone beam to melt the feed material at a molten zone interface to the single crystal rod, and the second paraboloid mirror directing the afterheater along a line lying along the crystal growth axis in an afterheater region of the single crystal rod.
A laser heated pedestal growth optical afterheater system for growing a single crystal rod, comprising:
- a device for growing a single crystal rod from a feed material via laser heated pedestal growth;
- a laser that generates a first laser beam;
- an optical train that separates the first laser beam into a molten zone beam and an afterheater beam, the optical train further including a power adjustment module positioned in an optical path of the afterheater beam;
- and
- a bifocal mirror positioned to direct the molten zone beam to melt the feed material at a molten zone interface to the single crystal rod, and to direct the afterheater beam to an afterheater region of the single crystal rod, the power adjustment module capable of adjusting an optical power of the afterheater beam and/or a focus of the afterheater beam in the afterheater region.
Dependencies are inferred from the claim text.