US 5,471,304 A · Laser positioning method and appartus for rotary actuator arms, and the like

Abstract

A laser interferometer or a single aperture Laser Doppler Displacement Meter (LDDM) is used to measure the precise position of a ninety degree notch or a flat reflecting surface on a rotating arm. For the case of using the ninety degree notch, a stationary flat mirror is used to reflect back the laser beam which follows the same beam path but in the opposite direction to the receiving aperture. For the case of using a flat reflecting surface, a stationary corner cube and a stationary flat mirror are used to reflect back the laser beam which follows the same beam path but in the opposite direction all the way to the receiving aperture. For both cases, the laser beams remain aligned even though the arm rotates a large angle. Hence, the position of the rotating arm can be determined. Since the notch or flat reflecting surface is attached or integral part of the arm, the disk drive can be enclosed with the laser beam passing through a window. Hence, the technique described is non-intrusive.

Claims11

Dependent claims

Apparatus for determining the angular position of a body about a fixed axis of rotation, said apparatus comprising:

reflecting means mounted on said body;
a stationary flat mirror mounted at a position displaced from said body;
laser means for producing a laser output beam and for directing said output beam to said reflecting means, said reflecting means reflecting said output beam as a first reflected beam and for directing said first reflected beam to said flat mirror along a path perpendicular to said flat mirror, said flat mirror being positioned to reflect said first reflected beam back to said reflecting means as a second reflected beam along the same path as said first reflected beam but in the opposite direction, and said reflecting means reflecting said second reflected beam back to said laser means along a path parallel to the path of said output beam but in the opposite direction as a return beam displaced from said output beam to enable said laser means to determine the angular position of said body with respect to said fixed axis of rotation.

Dependencies are inferred from the claim text.

Laser positioning method and appartus for rotary actuator arms, and the like

Life of this patent

Laser positioning method and appartus for rotary actuator arms, and the like

Life of this patent

Abstract

Claims11