NON-CONTACTING MEASURING PROBE

• US 3,692,414 A
• Filed: 02/24/1971
• Issued: 09/19/1972
• Est. Priority Date: 02/24/1971
• Status: Expired due to Term

• Current Assignee: Charles B. Barnett, Clarence A. Ripley Jr, Harry L. Hosterman
• Original Assignee: Charles B. Barnett, Clarence A. Ripley Jr, Harry L. Hosterman
• Inventors: Hosterman, Harry L., Barnett, Charles B., Ripley, Clarence A. Jr.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Rothenberg, Jeff
• Application Number:
  US05/118,311
• Time in Patent Office: 573 Days
• Field of Search: 356/120,167,4 250/236
• US Class Current: 356/608
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01S 17/46 Indirect determination of position data

Abstract

A non-contacting optical probe capable of giving a continuous reading of the distance from a given reference to a contoured surface. A collimated beam is projected on a first optical axis to the surface to be measured. A second optical axis extends from the surface to be measured at an angle to the first optical axis. When the projected beam meets the surface at the point of intersection of the second optical axis, a reflected beam passes along the second optical axis to a sensor which detects this beam. The projected light beam and its optical axis are caused to reciprocate at an angle to the surface, this being accomplished by passing the collimated beam through a rotating prism. The prism is a regular polygon. A second sensor detects the rotation of the prism. The distance to the surface being measured is detected as the interval of time between the detecting of the prism position by the second sensor and the detecting of the reflected light beam by the first sensor.

Claims

1. A non-contacting probe for determining the distance from a surface to a predetermined point, comprising:

means for projecting a light beam along a first axis;

an optical prism in the form of a regular polygon, the center of the prism lying on the first axis and the regular side faces thereof being normal to a plane containing the first axis;

means including a frequency responsive motor for rotating the prism to bring successive ones of the faces thereof through the first axis;

first detector means generating an output signal whenever an edge between adjacent faces of the prism passes a preselected point;

means to project the light beam emerging from the prism onto the surface;

means defining a second axis extending from the surface at an angle relative to the projected beam;

second detector means located on the second axis and generating an output signal when the projected light beam is reflected from the surface along the second axis;

means for generating first and second signals directly proportional to one another in frequency, the frequency of each signal being constant, the first signal driving the motor;

a pulse counter; and

gate means responsive to the output signals of the first and second detector means to supply the second frequency signal to the counter during the interval between the two output signals.

2. The non-contacting probe according to claim 1 wherein the means to generate comprises a stable oscillator and a divider network receiving the oscillator output signal and generating the first and second output signals therefrom.

3. The non-contacting probe according to claim 1 wherein the means projecting a light beam projects a monochromatic light beam, the means defining the second axis includes a dichroic mirror reflecting light of the wave length of the projected beam, and the probe further includes a light source generating a planar light beam including light of a wave length differing from that of the projected beam, the light source being located so as to project the planar beam through the mirror and along the second axis to strike the surface at right angles to the path of the projected beam.

4. The non-contacting probe according to claim 1 wherein the optical prism is a regular polygon having 2N + 2 sides, when N 1, 2, 3, 4, . . ..

5. The non-contacting probe according to claim 1 wherein the means to project the shifting light beam includes a second optical prism which directs the light beam emerging from the first prism along a path angled relative to the first axis.

6. The non-contacting probe according to claim 1 wherein each face of the prism is provided with a reflective band along one edge thereof and the first detector means includes a photosensor mounted so as to receive the light beam reflected by the band as the prism edge passes through the light beam from the light source.