Apparatus for measuring and positioning by interferometry

Claim 2

Apparatus for measuring the position of a work table relative to a tool head having a tool axis extending substantially perpendicular to the work surface of the table comprising: a first interferometer mounted on the head in the vicinity of the tool axis and having a measuring axis extending at least in part parallel to the work surface in a first coordinate direction along a first line intersecting the tool axis; a first reflector mounted on the work table and having a reflecting surface extending adjacent the work surface perpendicular to the first line and facing inwardly of the table toward the tool head; a second interferometer also mounted on the tool head in the vicinity of the tool axis and having a measuring axis extending at least in part parallel to the work surface in a second coordinate direction along a second line intersecting the tool axis and perpendicular to the first line; and a second reflector mounted on the work table and having a reflecting surface extending adjacent the work surface perpendicular to the second line and facing inwardly of the table toward the tool head.

Claim 3

Apparatus for measuring the position of a work table as defined in claim 1 wherein: the first interferometer is mounted on the tool head at a position about the tool axis directly opposite the first reflector mounted on the table.

Claim 4

Apparatus for measuring as defined in claim 2 wherein the first interferometer has said part of the measuring axis in the first coordinate direction extending between the tool head and the first reflector in close proximity to the work surface.

Claim 5

Apparatus for measuring as defined in claim 2 wherein: the first interferometer is mounted with a first portion of the measuring axis projecting from the interferometer toward the work surface; and an optical reflector is suspended below the interferometer to establish a second portion of the measuring axis extending in the first coordinate direction.

Claim 6

Apparatus for measuring as defined in claim 4 wherein: the optical reflector is suspended in close proximity to the work surface of the table.

Claim 7

Apparatus for measuring as defined in claim 4 wherein the optical reflector and the first interferometer are attached to a common mounting plate.

Claim 8

Apparatus for measuring the position of a work table as defined in claim 1 further including a laser for producing a laser beam; and means for directing the laser beam to the first and second interferometers.

Claim 9

Apparatus for measuring as defined in claim 7 wherein: the first and second interferometers are located 90* from each other about the tool axis; and the means for directing comprises a beam splitter having beam axes associated with the respective interferometers.

Claim 10

Apparatus as defined in claim 8 wherein the means for directing also includes two turning mirrors cooperating with the beam splitter to enable beams to reach the respective interferometers.

Claim 11

Apparatus as defined in claim 9 wherein the two turning mirrors, the beam splitter and the tool axis are spacially located at the corner of a rectangle.

Claim 12

A high accuracy positioning system for a work table defining a work surface movable in first and second coordinate directions relative to a tool head having a tool axis extending orthogonally of the two coordinate directions comprising: drive means including motor driven carriages for moving the work table in the first and second coordinate directions relative to the head; a first interferometer mounted to the tool head and having at least a portion of a measuring axis extending from the head in a direction intersecting the tool axis and parallel to the first coordinate direction; a first retroreflector mounted on the work table and intersecting said portion of the measuring axis of the first interferometer whereby the measuring axis extends from the head to the first retroreflector over the table; a second interferometer mounted to the tool head and having at least a portion of another measuring axis extending from the head in another direction intersecting the tool axis and parallel to the second coordinate direction; a second retroreflector mounted on the work table and intersecting said portion of the measuring axis of the second interferometer whereby the measuring axis extends from the head to the second retroreflector over the table; and control means connected with the interferometers and connected to the drive means for regulating the drive means in response to positional information detected through the interferometers along the respective measuring axes.

Claim 13

A high accuracy positioning system for a work table defining a work surface movable in first and second coordinate directions relative to a tool head having a tool axis extending orthogonally of the two coordinate directions comprising: drive means including motor driven carriages for moving the work table in the first and second coordinate directions relative to the head; a first interferometer mounted to the tool head and having at least a portion of a measuring axis extending from the head in a direction intersecting the tool axis and parallel to the first coordinate direction; a first retroreflector mounted on the work table and intersecting said portion of the measuring axis of the first interferometer whereby the measuring axis extends from the head to the first retroreflector over the table; a second interferometer mounted to the tool head and having at least a portion of another measuring axis extending from the head in another direction intersecting the tool axis and parallel to the second coordinate direction; a second retroreflector mounted on the work table and intersecting said portion of the measuring axis of the second interferometer whereby the measuring axis extends from the head to the second retroreflector over the table; and control means connected with the interferometers and connected to the drive means for regulating the drive means in response to positional information detected through the interferometers along the respective measuring axes.

Claim 14

A high accuracy positioning system as defined in claim 11 wherein: the first retroreflector extends along the table in the second coordinate direction a distance coextensive with the work surface in the second coordinate direction.

Claim 15

A high accuracy positioning system as defined in claim 12 wherein: the first retroreflector comprises a plane mirror reflector.

Claim 16

A high accuracy positioning system as in claim 11 wherein: the first and second interferometers are mounted at sides of the tool head opposite the first and second retroreflectors respectively.

Claim 17

A high accuracy positioning system as in claim 14 wherein a common mounting plate is provided for the first and second interferometers on the tool head.

Claim 18

A high accuracy positioning system as in claim 11 wherein: the first interferometer is mounted to the tool head adjacent the tool axis with a first portion of the measuring axis projecting from the first interferometer toward the work surface of the work table; and an optical reflector is suspended between the first interferometer and the work surface on the measuring axis to define a second portion of the measuring axis parallel to the first coordinate direction between the tool head and the first retroreflector.

Claim 19

A high accuracy positioning system as in claim 16 wherein: the optical reflector is suspended between the first interferometer and the work surface of the table in close Proximity to the work surface.