Wide angle bistatic scanning optical ranging sensor
View Patent ↗A sensor for determining a profile of an object surface relative to a reference plane includes a radiation source, a collector, a processor, first and second reflectors and at least one reflective element comprising third and fourth reflectors secured in mutual angular relation. The radiation source projects a launch beam for impingement onto the object surface. The collector detects at least a portion of a return beam reflected by the object surface. The processor determines the profile of the object surface at a point of impingement of the launch beam onto the object surface from at least one characteristic of the at least a portion of the return beam.
1. A sensor for determining a profile of an object surface relative to a reference plane, comprising:
a radiation source for projecting a launch beam for impingement onto the object surface;
a collector for detecting at least a portion of a return beam reflected by the object surface;
a processor for determining the profile of the object surface at a point of impingement of the launch beam onto the object surface from at least one characteristic of the at least a portion of the return beam;
a first reflector having first and second planar reflecting surfaces, the first reflecting surface for reflecting the launch beam along a first path, the second reflecting surface for reflecting the return beam along a second path, the first reflector being rotatable about a first axis substantially parallel to the reference plane, for controlling impingement of the launch beam on the object surface along a second axis substantially parallel to the reference plane and normal to the first axis;
a second reflector having a planar reflecting surface for reflecting the launch beam onto the object surface and for reflecting the return beam arriving from the object surface, the second reflector being rotatable about the second axis for controlling impingement of the launch beam on the object surface along the first axis;
at least one reflective element having third and fourth reflectors secured in mutual angular relation, the at least one reflective element disposed so as to be impinged upon by the launch beam between the first and second reflectors, the third reflector having a planar reflecting surface for receiving the launch beam after it is reflected off the first reflecting surface of the first reflector and reflecting it onto the fourth reflector, and the fourth reflector having a planar reflecting surface for reflecting the launch beam onto the reflecting surface of the second reflector for reflection onto the object surface.
2. A sensor according to claim 1 , wherein the first reflector is a spinning mirror having at least one other reflecting surface in addition to the first and second reflecting surfaces.
3. A sensor according to claim 1 , the first reflector rotatable under control of the processor to move a point of impingement of the launch beam on the object surface along the second axis.
4. A sensor according to claim 1 , the second reflector rotatable under control of the processor to move a point of impingement of the launch beam on the target surface along the first axis.
5. A sensor according to claim 1 , wherein a first end of the third reflector is positioned proximate to the first axis of the first reflector.
6. A sensor according to claim 5 , wherein a second end of the third reflector is positioned between the first end of the third reflector and the reference plane.
7. A sensor according to claim 6 , wherein the first end of the third reflector is positioned between the second end of the third reflector and the first axis.
8. A sensor according to claim 6 , wherein the second end of the third reflector is proximate to a first end of the fourth reflector.
9. A sensor according to claim 1 , wherein the reflecting surfaces of the third and fourth reflectors are substantially normal to each other.
10. A sensor according to claim 1 , wherein the at least one reflective element comprises a refractive boundary, through which the launch beam passes after reflection off the fourth reflector and before reflection onto the object surface.
11. A sensor according to claim 10 , wherein the refractive boundary causes the launch beam, if incident on the refractive boundary at an angle to a normal axis of the boundary, to be refracted through the boundary at an increased angle.
12. A sensor according to claim 10 , wherein the refractive boundary is substantially parallel to the reference plane.
13. A sensor according to claim 10 , wherein the refractive boundary extends between a first end of the third reflector positioned proximate to the first axis of the first reflector and a second end of the fourth reflector, a second end of the third reflector and a first end of the fourth reflector being proximate to each other.
14. A sensor according to claim 10 , wherein the refractive boundary is substantially parallel to the second axis.
15. A sensor according to claim 1 , wherein the at least one reflective element is a prism.
16. A sensor according to claim 15 , wherein the prism is a pentaprism.
17. A method for determining a profile of a object surface relative to a reference plane, comprising:
projecting a launch beam onto a planar first reflecting surface of a first reflector that is rotatable about a first axis substantially parallel to the reference plane;
projecting the launch beam reflected by the first reflecting surface of the first reflector onto a planar reflecting surface of a second reflector of at least one reflecting element;
projecting the launch beam reflected by the reflecting surface of the second reflector onto a planar reflecting surface of a third reflector secured in mutual angular relation in the at least one reflecting element with the second reflector;
projecting the launch beam reflected by the reflecting surface of the third reflector onto a planar reflecting surface of a fourth reflector that is rotatable about a second axis substantially parallel to the reference plane and substantially normal to the first axis;
projecting the launch beam reflected by the reflecting surface of the fourth reflector onto the object surface at a point of impingement;
projecting a return beam reflected by the object surface at the point of impingement onto the reflecting surface of the fourth reflector;
projecting the return beam reflected by the reflecting surface of the fourth reflector onto a planar second reflecting surface of the first reflector;
projecting the return beam reflected by the second reflecting surface of the first reflector toward a collector;
detecting at least a portion of the return beam directed toward the collector; and
processing at least one characteristic of at least a portion of the return beam to determine the profile of the object surface at the point of impingement of the launch beam on the object surface.
18. A method according to claim 17 , further comprising controlling rotation of the first reflector to move the point of impingement of the launch beam on the object surface along the second axis.
19. A method according to claim 17 , further comprising controlling rotation of the fourth reflector to move the point of impingement of the launch beam on the object surface along the first axis.
20. A method according to claim 17 , further comprising refracting the launch beam reflected from the reflecting surface of the third reflector through a refractive boundary of the at least one reflective element before projecting it onto the reflecting surface of the fourth reflector.