Apparatus for the orientation of crystals

Claim 1

AN APPARATUS FOR DETERMINING THE ORIENTATION OF A SINGLE CRYSTAL HAVING AN ETCHED SURFACE WHERE THE APPROXIMATE CRYSTALLOGRAPHIC PLANE OF THE CRYSTAL IS KNOWN, COMPRISING: (A) A GRATICULE HAVING ITS LINES FORMING A SCALE SYMMETRICAL ABOUT A CENTRAL SPOT OF THE GRATICULE; (B) MEANS FOR ILLUMINATING THE GRATICULE WITH ITS CENTRAL SPOT BEING ILLUMINATED TO A GREATER INTENSITY THAN THE REMAINDER OF THE SCALE; (C) A PARTIAL REFLECTING PLANE MIRROR SPACED A PREDETERMINED DISTANCE FROM THE GRATICULE; (D) MEANS FOR DIRECTING THE LIGHT EMANATING FROM THE GRATICULE TO BE INCIDENT ON ONE SIDE OF SAID MIRROW, THE REFLECTION THEREFROM FORMING A FIRST VIRTUAL IMAGE OF THE ILUMINATED GRATICULE; (E) THE APPARATSU BEING ARRANGED TO HAVE THE ETCHED SURFACE OF THE CRYSTAL TO BE TESTED PLACED IN CLOSE PROXIMITY TO AND PARALLEL WITH THE OPPOSITE SIDE TO SAID ONE SAID OF SAID MIRROR, WHEREBY, WHEN THE CRYSTAL IS SO PLACED, THE ETCHED SURFACE THEREOF ALSO REFLECTS THE LIGHT EMANATING FROM THE GRATICULE TO FORM A SECOND VIRTUAL IMAGE OF THE ILLUMINATED GRATICULE SUPERIMPOSED ON THE FIRST VIRTUAL IMAGE AND SUBSTANTIALLY IN THE SAME PLANE THEREOF, SAID DIRECTING MEANS PERMITTING THE SIMULTANEOUS VIEWING OF SAID FIRST AND SECOND VIRTUAL IMAGES OF THE ILLUMINATED GRATICULE AND ITS CENTRAL SPOT, WHEREBY THE ORIENTATION OF THE CRYSTAL MAY BE OBTAINED FROM THE VISUAL LOCATION OF THE CENTER OF THE SECOND VIRTUAL IMAGE WITH RESPECT TO THE SCALE OF THE FIRST VIRTUAL IMAGE.