Verfahren und Vorrichtung zur Erhöhung der Lebensdauer eines Saphir-Fensters in einer Hochbeanspruchungsumgebung

A dome assembly (50) adapted for use with a missile (32) having a longitudinal axis (42) parallel to a thrust vector thereof. The inventive dome (50) includes a sapphire crystal (30) having a crystallographic structure that includes positive n-planes (12), positive r-planes (14) and a c-plane (16). A surface around a missile sensor provides a place for mounting the crystal (30, 50) such that one of said positive r-planes faces leeward with respect to wind flow (36) that impinges on said missile (32) during missile flight. The projection of one of the positive r-plane normals onto the wind flow vector (36) points aft. By design at nominal conditions, an r-plane (14) is approximately bisected by a plane formed by the normal of the c-plane (16) and a wind flow vector (36). In the illustrative embodiment, the dome assembly (50) includes an x-ray device for locating the r-planes planes within the sensor dome (50). A turntable (not shown) orients the sensor dome (50) so that a first r-plane (14) faces leeward of impinging air flow (36). An r-plane normal (38) of a second r-plane forms an angle of approximately 60 degrees with respect to impinging airflow (36). The turntable includes a motor (not shown) for strategically orienting the lattice planes (12, 14, 16) of the dome (50) so as to maximize the strength of the dome (50) with respect to applied stresses.