Apparatus for detecting angular deviations

Claim 1

APPARATUS FOR DETECTING SMALL ANGULAR DEVIATIONS OF A FERROMAGNETIC FILM, COMPRISING (A) A FERROMAGNETIC FILM HAVING THE PROPERTY OF UNIAXIAL ANISOTROPY WITH AN EASY AXIS OF MAGNETIZATION WHOSE MAGNETIZATION VECTOR HAS A LARMOR FREQUENCY OF PRECESSION AT LEAST IN THE ULTRA-HIGH FREQUENCY RANGE IN THE ABSENCE OF ANY EXTERNALLY APPLIED MAGNETIC FIELD, (B) MEANS FOR SUSPENDING SAID FILM ABOUT AN AXIS OF ROTATION, SAID AXIS BEING IN THE PLANE OF SAID FILM AND SUBSTANTIALLY PERPENDICULAR TO SAID AXIS EASY AXIS, (C) MEANS FOR APPLYING A STEADY MAGNETIC FIELD SUBSTANTIALLY PERPENDICULAR TO SAID AXIS OF ROTATION SUCH THAT A COMPONENT OF STEADY FIELD LIES IN THE PLANE OF SAID FILM SUBSTANTIALLY PARALLEL TO SAID EASY AXIS AND THE MAGNITUDE OF SAID COMPONENT INCREASES FROM ZERO AS A FUNCTION OF THE ANGLE OF ROTATION OF THE PLANE OF SAID FILM FROM A POSITION PERPENDICULAR TO SAID STEADY FIELD, (D) A FIRST COIL POSITIONED IN THE VICINITY OF SAID FILM FOR APPLYING A RADIO FREQUENCY MAGNETIC FIELD TO SAID FILM SUBSTANTIALLY PERPENDICULAR TO BOTH SAID AXIS OF ROTATION AND SAID STEADY MAGNETIC FIELD, AND (E) A SECOND COIL POSITIONED IN THE VICINITY OF SAID FILM FOR APPLYING A LOW FREQUENCY MAGNETIC FIELD TO SAID FILM SUBSTANTIALLY PARALLEL WITH SAID AXIS OF ROTATION FOR REDUCING SAID PRECESSION FREQUENCY TO THE RADIO FREQUENCY RANGE, (F) WHEREBY ENERGY IS ABSORBED FROM SAID FIRST COIL BY SAID FILM WHEN SAID PRECESSION FREQUENCY APPROACHES THE RADIO FREQUENCY OF SAID FIRST COIL AS FILM IS ROTATED FROM A REFERENCE POSITION, AND (G) MEANS FOR DETECTING AND INDICATING THE ABSORPTION OF RADIO FREQUENCY ENERGY FROM SAID FIRST COIL TO PROVIDE A MEASURE OF THE ANGLE OF RATATION OF SAID FILM FROM SAID REFERENCE POSITION.