Transmitter and receiver units for spatial position measurement system

• US 5,579,102 A
• Filed: 10/05/1995
• Issued: 11/26/1996
• Est. Priority Date: 06/17/1991
• Status: Expired due to Term

• Current Assignee: Nikon Metrology NV (Nikon Corporation)
• Original Assignee: Spatial Positioning Systems, Inc.
• Inventors: Dornbusch, Andrew W., Lundberg, Eric J., Beliveau, Yvan J., Sweeney, Michael H., Pratt, Timothy
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US08/539,379
• Time in Patent Office: 418 Days
• Field of Search: 356/4.08, 356/3.09, 356/3.12, 356/141.3, 356/141.4, 359/709, 359/712, 33/293, 250/206.1, 250/208.6, 172/4.5
• US Class Current: 356/3.12
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4813 Housing arrangements

Abstract

Improved transmitter and receiver units for use in spatial measurement system that are easy and inexpensive to manufacture while providing a high degree of reliability are disclosed. Specifically, the laser transmitter includes a laser emitter, a bearing/motor assembly coupled to the laser emitter, the bearing/motor assembly including a rotatable hollow spindle shaft through which a laser beam generated by the laser emitter passes and a motor for driving the spindle shaft, a prism assembly coupled to the spindle shaft, wherein the prism assembly divides the laser beam generated by the laser emitter into a pair of fanned laser beams, and reflecting means for reflecting the fanned laser beams generated by the prism assembly as counter-rotating fanned laser beams. The receiver unit preferably includes at least one optical receiver coupled to an extension member, a processing unit coupled to the optical receiver, and a receiver interface coupled to the processing unit.

Claims

1. A laser transmitter unit for a spatial measurement system comprising:

a laser emitter;

a bearing/motor assembly coupled to the laser emitter, the bearing/motor assembly including a rotatable hollow spindle shaft through which a laser beam generated by the laser emitter passes and a motor for driving the spindle shaft;

a prism assembly coupled to the spindle shaft, wherein the prism assembly divides the laser beam generated by the laser emitter into a pair of fanned laser beams; and

reflecting means for reflecting the fanned laser beams generated by the prism assembly as counter-rotating fanned laser beams.

2. A laser transmitter unit as claimed in claim 1, further comprising a cylindrical exit window through which the fanned laser beams are reflected by the reflecting means.

3. A laser transmitter unit as claimed in claim 1, wherein the reflecting means comprises a 90 degree fold mirror.

4. A laser transmitter unit as claimed in claim 1, wherein the prism assembly includes a first beam splitting prism coupled to a second reflective prism.

5. A laser transmitter unit as claimed in claim 1, wherein a light emitting side of the first beam splitting prism is offset from a light emitting side of the second reflective prism, with respect to an axis of rotation of the prism assembly, by an angle phi.

6. A laser transmitter unit as claimed in claim 5, wherein the light emitting side of the first beam splitting prism and the light emitting side of the reflecting prism each include a cylindrical lens.

7. A laser transmitter unit as claimed in claim 6, wherein the cylindrical lens of the first beam splitting prism is rotated with respect to the cylindrical lens of the second reflecting prism by an angle gamma.

8. A laser transmitter unit as claimed in claim 6, further comprising dummy cylindrical lenses bonded to second sides of the first beam splitting prism and the second reflecting prism opposite to the light emitting sides thereof.

9. A laser transmitter unit as claimed in claim 1, wherein the reflecting means comprises a ninety degree fold mirror.

10. A laser transmitter unit as claimed in claim 1, wherein the bearing/motor assembly includes a hydrodynamic gas bearing.

11. A spatial measurement system comprising:

at least two transmitter units and at least one receiver unit, wherein the transmitter units include a laser emitter;

a bearing/motor assembly coupled to the laser emitter, the bearing/motor assembly including a rotatable hollow spindle shaft through which a laser beam generated by the laser emitter passes and a motor for driving the spindle shaft;

a prism assembly coupled to the spindle shaft, wherein the prism assembly divides the laser beam generated by the laser emitter into a pair of fanned laser beams; and

reflecting means for reflecting the fanned laser beams generated by the prism assembly as counter-rotating fanned laser beams; and

wherein the receiver unit includes at least one optical receiver coupled to an extension member;

a processing unit coupled to the optical receiver; and

a receiver interface coupled to the processing unit.

12. A spatial measurement system as claimed in claim 11, wherein at least two transmitter units are commonly mounted on a rotation device.

13. A spatial measurement system as claimed in claim 11, wherein the receiver unit is a telescopic receiver unit.