Method and apparatus for determining the position and the configuration of an object under observation

• US 5,383,026 A
• Filed: 04/23/1992
• Issued: 01/17/1995
• Est. Priority Date: 08/07/1991
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Naotake Mouri
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Naotake Mouri
• Inventors: Akamatsu, Koji, Mouri, Naotake, Goto, Akihiro
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US07/872,305
• Time in Patent Office: 999 Days
• Field of Search: 356/128, 356/376, 356/375, 356/377, 356/336, 356/338, 356/337, 356/371, 356/445, 356/1, 356/4, 356/141, 356/152, 250/561, 219/121.6, 219/121.78, 219/121.62
• US Class Current: 356/602
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures

Abstract

The invention permits determination of the position and/or the configuration of an object by impinging a laser light beam onto the object in a light scattering medium, and detecting the trace of a scattered light beam, by cameras.

Claims

1. A method for determining a position of a point on an object, comprising steps of:

impinging on said object an incident laser beam emitted from a laser, said object directing said incident beam as a reflected beam which is received by a camera, said incident and reflected beams defining a laser beam path;

providing a light scattering medium into the laser beam path so as to produce visible scattered light;

detecting the visible scattered light by at least one detection means located at a position not on said laser beam path extending from said laser to said camera in order to determine a locus of said laser beam.

2. The method according to claim 1, wherein a position vector on the point on an object from an arbitrary point is determined by detecting the scattered light of the laser beam.

3. The method according to claim 2, wherein a position represented by a vector R_b on the point of an object from an arbitrary point is determined from an Equation:

space="preserve" listing-type="equation">R.sub.b =R.sub.L +d·

n.sub.L =R.sub.c +c·

n.sub.b

where R_L and R_c are the position vectors of said laser and said camera, respectively, in reference to an arbitrary origin O, n_L is the unit vector pointing in the direction of the laser beam emitted from said laser, n_b is the unit vector pointing from said camera to said point on said object and d is the distance from said laser to the point on the object.

4. The method according to claim 2, wherein a position represented by a position vector R_b on the point of an object from a arbitrary point is determined by:

detecting two points A₁ and B on said scattered laser beam by said camera, and

determining a unit vector n_L pointing the direction of said laser beam emitted from said laser source, from following Equations;

space="preserve" listing-type="equation">A.sub.1 ;

a+R.sub.L =R.sub.c +d.sub.1 ·

n.sub.b1

space="preserve" listing-type="equation">B;

α

a+R.sub.L =R.sub.c +d.sub.2 ·

n.sub.b2

space="preserve" listing-type="equation">a=R.sub.c -R.sub.L +d.sub.1 ·

n.sub.b1

space="preserve" listing-type="equation">n.sub.L =a/|a|

where R_L and R_c are the position vectors of said laser and said camera, respectively, in reference to said arbitrary point, n_b1 and n_b2 are the unit vector pointing the direction form said camera to respective points A₁ as viewed form said laser, α

a is a position vector of said point B as viewed from said laser source, and d₁ and d₂ are the distances from said camera to said points A₁ and B, respectively.

5. The method according to claim 1, wherein said detecting means is located non-coaxially with respect to the laser beam path.

6. The method according to claim 1, wherein the position of a plurality of points on an object are determined.

7. The method according to claim 6, further comprising moving said medium past said plurality of points.

8. The method according to claim 7, further comprising step of making doppler laser measurements of said moving medium.

9. The method according to claim 1, further comprising the step of compensating for the refractive index of said light scattering medium

10. The method according to claim 1, further comprising measuring spacial intensity distribution of said reflected beam.

11. A method for determining a position of a point on an object, comprising the steps of:

impinging on said object an incident laser beam emitted from a laser, said object directing said incident beam as a reflected beam, said incident and reflected beams defining a laser beam path;

providing a light scattering medium into the laser beam path; and

detecting a locus of said laser beam by at least one detection means located at a position not on said laser beam path;

wherein a position vector on the point on an object from an arbitrary point is determined by detecting the scattered light of the laser beam; and

wherein a position represented by a position vector R_b on the point on the object from an arbitrary point is determined by detecting the point by a first and a second camera, from the following Equations;

space="preserve" listing-type="equation">d.sub.1 ·

n.sub.b1 +R.sub.C1 =d.sub.2 ·

n.sub.b2 +R.sub.C2

space="preserve" listing-type="equation">R.sub.b =d.sub.1 ·

n.sub.b2 +R.sub.C1

where R_C1 and R_C2 are the position vectors of said first and second camera, respectively, n_b1 and n_b2 are the unit vectors pointing in the directions from said first and second camera, respectively, to said point B on said object, and d₁ and d₂ are the distances from said first and second camera, respectively, to said point B on said object.

12. An apparatus for determining a position of a point on an object, comprising:

a laser source for emitting a laser beam;

a light scatting medium for scattering the laser beam;

at least one camera for detecting said scattered laser beam light;

wherein a position represented by a vector R_b on the point of the object from an arbitrary point is determined, from the following Equation;

space="preserve" listing-type="equation">R.sub.b =R.sub.L +d·

n.sub.L =R.sub.c +c·

n.sub.b

where R_L and R_c are the position vectors of said laser and a camera, respectively, in reference to an arbitrary origin O, n_L is the unit vector pointing in the direction of the laser beam emitted from said laser, n_b is the unit vector pointing from said camera to said point on said object, d is the distance from said laser to the point on the object and c is the distance form the camera to the point of the object.

13. The apparatus according to claim 12, wherein said camera is disposed non-coaxially with respect to said laser beam.

14. The apparatus according to claim 12, wherein said laser beam is movable to a plurality of points on an object.

15. The apparatus according to claim 12, wherein said medium is at least one of a gas and a liquid.

16. An apparatus for determining a position of a point on an object, comprising:

a laser source for emitting a laser beam;

a light scatting medium for scattering the laser beam;

at least one camera for detecting said scattered laser beam light;

wherein a position represented by a vector R_b on the point of the object from an arbitrary point is determined by detecting two points A₁ and B on said scattered laser beam by a camera, and by determining the unit vector n_L pointing in the direction of said laser beam emitted from said laser source, from the following Equations;

space="preserve" listing-type="equation">A.sub.1 ;

a+R.sub.L =R.sub.c +d.sub.1 ·

n.sub.b1

space="preserve" listing-type="equation">B;

α

a+R.sub.L =R.sub.c +d.sub.2 ·

n.sub.b2

space="preserve" listing-type="equation">a=R.sub.c -R.sub.L +d.sub.1 ·

n.sub.b1

space="preserve" listing-type="equation">n.sub.L =a/|a|

where n_b1 and n_b2 are the unit vector pointing in the direction from said camera to respective points A₁ and B, respectively, a is a position vector of said point A₁ as viewed from said laser, α

a is a position vector of said point B as viewed from said laser, and d₁ and d₂ are the distances from said camera to said points A₁ and B, respectively.

17. An apparatus for determining a position of a point on an object comprising:

a laser source for emitting a laser beam;

a light scatting medium for scattering the laser beam;

at least one camera for detecting said scattered laser beam light;

wherein a position represented by a vector R_b on the point B from an arbitrary point is determined, by detecting a points B on said scattered laser beam by first and second cameras, from the following Equations;

space="preserve" listing-type="equation">d·

n.sub.b1 +R.sub.C1 =d.sub.2 ·

n.sub.b2 +R.sub.C2

space="preserve" listing-type="equation">R.sub.b =d.sub.1 ·

n.sub.b1 +R.sub.C1

wherein R_C1 and R_C2 are the position vectors of said first and second cameras, respectively, n_b1 and n_b2 are the unit vectors pointing in the directions from said first and second cameras, respectively, to said point B on said object, and d₁ and d₂ are the distances from said first and second cameras, respectively, to said point B on said object.