SELF-LEVELLING LASER REFERENCE PLANE

• US 3,762,820 A
• Filed: 08/18/1970
• Issued: 10/02/1973
• Est. Priority Date: 08/18/1970
• Status: Expired due to Term

• Current Assignee: Gilbert E. Erb, Robert M. Zoot
• Original Assignee: Gilbert E. Erb, Robert M. Zoot
• Inventors: Zoot, Robert M., Erb, Gilbert E.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/064,732
• Time in Patent Office: 1,141 Days
• Field of Search: 356/152,150,172 340/258B
• US Class Current: 356/141.1
• CPC Class Codes: G01C 15/004 Reference lines, planes or sectors

Abstract

Apparatus for establishing a horizontal self-correcting plane using light from a laser or other optical source to establish a geometric form whose plane is normal to the gravitational vector. The apparatus maintains the reference plane horizontal, regardless of supporting surface shifts or other displacements.

Claims

1. A system for establishing and maintaining a self-levelling reference plane comprising:

a plurality of spaced oriented individual reference devices aligned at corners of a geometrical pattern in a reference plane;

each of said devices having a beam source and a beam receiver oriented at an angle to each other defined by the angle of the corner in which said device is disposed, such that said beam source is aligned along one boundary defining said corner and said beam receiver is aligned along the other of said boundaries defining said corner;

each said device also including means responsive to the beam receiver for providing an indication of the orientation of a beam received from a next adjacent device in said system and means positioned in the path of a beam from said beam source for automatically maintaining the beam from said source in a level attitude.

2. A system in accordance with claim 1 wherein said beam levelling means comprises gravity responsive means for controlling the direction of the beam therethrough in accordance with the deviation of a selected portion of said means from a true vertical orientation.

3. A system in accordance with claim 1 wherein said beam receiver comprises a beam splitter and a photoresponsive quadcell for developing comparison signals corresponding to the deviation of the received beam from the center of the quadcell.

4. A system in accordance with claim 3 wherein said quadcell comprises a horizontally-disposed pair of photo-conductive segments and a vertically-disposed pair of photo-conductive segments, and further including a vertical indicator coupled to said vertically-disposed pair and a horizontal indicator coupled to said horizontally-disposed pair for indicating the position of the beam relative to the center of the quadcell.

5. A system in accordance with claim 3 wherein each device further includes another photoresponsive element positioned to receive a reflected beam from the beam splitter of an adjacent device for developing signals indicative of the angle of said reflected beam.

6. A system in accordance with claim 5 further including indicators coupled to said photoresponsive element for providing indications of azimuth and elevation angles respectively.

7. A system for establishing a self-levelling reference plane comprising:

a plurality of individual devices positioned respectively at corner positions in said plane;

each of said devices including a beam source and means at right angles to the beam from said source for receiving a beam directed from an adjacent one of said devices;

means for locating the first of said devices at a particular position and orientation relative to a reference object;

means for locating a second of said devices at a particular position and orientation relative to said object and said first device;

means for locating a third of said devices at a particular distance and orientation relative to said second device; and

means for locating the fourth of said devices at a particular position and orientation relative to said third and first devices.

8. A system in accordance with claim 7 wherein all of said devices are substantially alike in construction and function such that they may be intermixed with respect to the various positions in the system.

9. A system in accordance with claim 7 further including a corner extender device having a beam receiver with indicating means coupled thereto for permitting the relocation of one of said first-mentioned devices along a first reference line extending past the original corner location of said device, and for establishing a second reference line along the path of the beam incident on said relocated device when said relocated device was in its initial corner location.

10. A system in accordance with claim 7 further including vertical position servo means for automatically adjusting the elevation of said devices and the associated self-levelling reference plane established thereby.

11. A system in accordance with claim 7 further including means for developing a warning signal upon detection of a deviation of any one of said beams from a predetermined position by an amount in excess of a preselected limit.

12. The method of maintaining a self-levelling reference plane established by a plurality of beam devices, each of said devices including a beam source and a beam detector disposed at a predetermined angle to each other, while removing one of said devices from its corner position defined as the point of intersection of its own beam which is directed towards a succeeding adjacent beam device and the beam of the preceding adjacent beam device, said method comprising the steps of:

positioning a beam-receiving corner extender in the beam path of the beam device to be displaced;

removing the beam device to be displaced from its corner position along a first reference line defined by said corner extender and the succeeding adjacent beam device until the desired clearance is developed at said corner position;

bringing said corner extender to a second position along a reference line defined by the beam path of the preceding adjacent beam device; and

operating said corner extender to maintain said reference line as a part of the reference plane defined by the aligned beams of said plurality of beam devices.

13. Apparatus for use in developing and maintaining a portable self-levelling reference plane comprising a beam source and a beam receiver having central longitudinal axes fixed at a predetermined right angle to each other, and beam levelling means positioned to transmit a beam from said beam source after correcting any deviation thereof from a level orientation.

14. Apparatus in accordance with claim 13 further including a base platform and means for levelling said platform.

15. Apparatus in accordance with claim 14 further including a table mounted on said platform and means for adjusting the position of said table relative to said platform in two orthogonal directions.

16. Apparatus in accordance with claim 15 further including means for mounting said beam source and beam receiver on said table, said last-mentioned means including angular adjusting means for controlling the angular direction of the beam from the beam source relative to said table.

17. Apparatus in accordance with claim 13 further including indicating means coupled to said beam receiver for providing an indication of the location of an incident beam relative to said receiver.

18. Apparatus in accordance with claim 16 wherein said beam receiver comprises a photoresponsive quadcell having a first pair of horizontally-disposed segments and a second pair of vertically-disposed segments, said indicating means including a horizontal indicator coupled to the output of said first pair of segments and a vertical indicator coupled to the output of the second pair of segments.

19. Apparatus in accordance with claim 13 wherein said beam receiver comprises a beam splitter for reflecting a portion of an incident beam back toward the source of the beam.

20. Apparatus in accordance with claim 13 further including a second beam receiver and second indicating means for providing an indication of the angle of a beam incident on said second beam receiver.

21. Apparatus in accordance with claim 20 wherein said second indicating means provides indications of azimuth and elevation angle respectively.