Coaxial disc-mount for measuring flatness of computer-drive discs by interferometry
AssigneeWyko Corporation
InventorsJoseph A. Lamb, Jr., Chiayu Ai
Life of this patent
Estimating the term…
Abstract
An interferometer mounting mechanism that consists of a horizontal shaft rigidly connected to the interferometer in axial alignment with the optical path of the instrument and protruding through an opening in the center of the transmission flat. A sample stage adapted to receive a computer-drive disk is attached to the distal end of the shaft, so that the stage is directly and rigidly connected to the interferometer. The sample stage consists of a hub capable of retaining a disk in precise alignment with the transmission flat by hanging its center hole on two support posts and resting the disk on three pressure tips on the hub. A system of push-pull adjustment screws is provided to set the proper tip/tilt of the disk.
Claims31
A mounting mechanism for an interferometric device to scan a test surface of a structure containing a hole, wherein said test surface is aligned along an optical axis of the device, said mechanism comprising:
- (a) a reference surface having an opening therewithin substantially aligned with said optical axis;
- (b) support means for supporting said test surface, said support means having a proximal end connected to the device and a distal end protruding through said opening in the reference surface in substantial alignment with said optical axis;
- and
- (c) mounting means for mounting and holding in place said test surface on said distal end of the support means, such that the test surface is in substantial alignment with said optical axis and said hole is substantially aligned with said opening in the reference surface, whereby a test beam of light transmitted through the reference surface illuminates said test surface.
A mounting mechanism for an interferometric device for scanning a test surface of a computer-drive disk having a center hole, wherein said test surface is aligned along an optical axis of the device, said mechanism comprising:
- (a) a reference surface having an opening substantially centrally-located therewithin and substantially aligned with said optical axis;
- (b) support means for supporting said test surface, said support means having a proximal end connected to the device and a distal end protruding through said opening in the reference surface in substantial alignment with said optical axis;
- (c) mounting means for mounting and holding in place said test surface, said mounting means comprising a base fixture rigidly connected to said distal end of the support means in substantial alignment with said optical axis and comprising a tip/tilt plate disposed substantially in parallel with the base fixture, said tip/tilt plate comprising at least one support post from which the test surface can be suspended through said center hole, whereby a test beam of light transmitted through the reference surface illuminates said test surface;
- (d) a resilient O-ring disposed between said base fixture and said tip/tilt plate;
- (e) three pressure tips on said tip/tilt plate defining a plane to provide a support against which said test surface can rest while suspended from said at least one support post;
- and
- (f) adjustment means for adjusting a position of said test surface in relation to said reference surface;
- wherein said opening in the reference surface is no larger that approximately the size of said center hole in the disk to be tested.
An interferometric method for scanning a test surface of a structure having a hole, wherein said test surface is aligned with a reference surface along an optical axis of an interferometric device, said method comprising the following steps:
- (a) providing an opening within said reference surface;
- (b) providing a support means for supporting said test surface, said support means having a proximal end connected to the device and a distal end protruding through said opening in the reference surface in substantial alignment with said optical axis;
- (c) providing mounting means for receiving and holding in place said test surface on said distal end of the support means such that the test surface is in substantial alignment with said optical axis;
- (d) mounting said test surface on said mounting means on the distal end of the support means;
- and
- (e) varying an optical path difference between said reference and test surfaces to produce interference fringes.
Dependencies are inferred from the claim text.