Apparatus for determining surface contour

Claim 1

APPARATUS FOR MEASURING THE THICKNESS OF AN ARTICLE COMPRISING A TABLE FOR SUPPORTING SAID ARTICLE, A FIRST MEANS FOR PRODUCING A BEAM OF ENERGY, A SECOND MEANS FOR PRODUCING A BEAM OF ENERGY, BOTH OF SAID BEAM PRODUCING MEANS BEING SITUATED ON THE SIDE OF THE ARTICLE OPPOSITE THE TABLE, MEANS FOR ROTATING SAID FIRST BEAM PRODUCING MEANS ON AN AXIS AT A FIXED OBLIQUE ANGLE WITH THE PLANE OF THE TABLE SURFACE, MEANS FOR ROTATING SAID SECOND BEAM PRODUCING MEANS ON AN AXIS AT A FIXED OBLIQUE ANGLE WITH THE PLANE OF THE TABLE SURFACE, SAID AXES BEING IN THE SAME PLANE, SAID BEAM PRODUCING MEANS BEING SO POSITIONED THAT THEIR RESPECTIVE BEAMS WILL INTERSECT AT A LINE THE LOCATION OF WHICH WITH RESPECT TO SAID TABLE IS KNOWN, AND MEANS FOR MEASURING THE DISTANCE BETWEEN THE IMAGES OF THE BEAM ON THE ARTICLE WHILE MAINTAINING THE ANGLES OF IMPINGEMENT OF SAID BEAMS FIXED WITH RESPECT TO SAID TABLE, SAID MEASURING MEANS INCLUDING MEANS FOR PHOTOGRAPHING THE IMATES FORMED BY THE SAID BEAM PRODUCING MEANS, AND MEANS FOR MEASURING THE DISTANCE BETWEEN THE LINES ON THE PHOTOGRAPH, SAID LAST NAMED MEANS BEING CALIBRATED TO COMPENSATE FOR THE DIFFERENT IN THE TRUE DISTANCE BETWEEN SAID IMAGES AND THE DISTANCE BETWEEN THE LINES ON THE PHOTOGRAPH.