Surface sensing device with optical sensor

• US 20090040534A1
• Filed: 04/26/2006
• Published: 02/12/2009
• Est. Priority Date: 04/26/2005
• Status: Active Grant

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: McFarland, Geoffrey, Jonas, Kevyn Barry
• Granted Patent: US 7,847,955 B2
• Time in Patent Office: Days
• US Class Current: 356/614
• CPC Class Codes: G01B 11/007 feeler heads therefor
• CPC Class Codes: G01B 5/012 Contact-making feeler heads therefor

Abstract

A surface sensing device for use in position determining apparatus has an elongate stylus (74) with a tip (82) for scanning the surface of a workpiece to be measured. Lateral displacements of the stylus tip are detected by a light beam which passes along the stylus from a light source (66) to a retroreflector (78). This reflects the beam back via a beamsplitter (70) to a position sensitive detector (76). The stylus is mounted for longitudinal displacement on a carriage (72). The longitudinal displacement is measured by another light beam projected by the beamsplitter (70) onto a second position sensitive detector (84).

Claims

1. A surface sensing device for use in position determining apparatus, comprising:

an elongate stylus having a workpiece-sensing stylus tip;

an optical element at or near or connected to the tip so as to be subjected to lateral displacements of the tip;

an optical transducer system which projects a light beam between the optical element and a detector, thereby to measure said lateral displacements of the tip;

wherein the stylus is mounted in the surface sensing device for longitudinal displacement; and

means are provided for measuring said longitudinal displacement.

2. A surface sensing device according to claim 1, wherein the stylus is bendable to permit said lateral displacements of the tip.

3. A surface sensing device according to claim 1, wherein the means for measuring longitudinal displacement comprises a further light beam projected onto a further detector.

4. A surface sensing device according to claim 3, including a beamsplitter which derives both light beams from a common light source.

5. A surface sensing device according to claim 1, wherein the stylus is mounted on a longitudinally movable carriage.

6. A surface sensing device according to claim 5, wherein the carriage is mounted for longitudinal movement on a pair of parallel leaf springs or diaphragms.

7. A surface sensing device for use in position determining apparatus, comprising:

a bendable elongate stylus having a workpiece-sensing stylus tip;

said tip being subjected to lateral displacements caused by bending of the stylus;

a transducer system which measures lateral displacements of the tip, including those caused by said bending of the stylus;

wherein the stylus is mounted in the surface sensing device for longitudinal displacement; and

means are provided for measuring said longitudinal displacement.

8. A surface sensing device according to claim 7, wherein the transducer system is optical.

9. A surface sensing device according to claim 8, wherein the transducer system includes an optical element at or near or connected to the tip so as to be subjected to the lateral displacements of the tip, and projects a light beam between the optical element and a detector.

10. A surface sensing device according to claim 7, wherein the means for measuring longitudinal displacement comprises a light beam projected onto a detector.