Laser beam centering and pointing system
View Patent ↗An optical instrument aligns an optical beam without the need for physical intervention of the instrument within the apparatus or platforms from which the trajectory of the beam to be ascertained. The alignment apparatus and method enable the desired function to be realized without the placement of physical apertures or sensors directly in the path of the beam through the system whose spatial position and slope is to be sought. An image plane provides the observer with a pair of well-defined images that are indicative of the beam centering and pointing alignment parameters. The optical alignment can be realized without the need for referencing to an external or fixed set of coordinates or fiducials. The instrument can therefore service situations where adverse environments would otherwise prohibit the use of such instruments, including regions of high radiation, high temperature, vacuum and/or cryogenic atmospheres.
1. A method, comprising:
directing a beam of light on or about an optical axis that terminates at an image plane, wherein said beam passes through a first object and then through a second object and then through an optical element before propagating onto said image plane, wherein said first object is fixedly placed in line with said optical axis, wherein said first object is configured to impart a first pattern on said beam as it propagates on or about said optical axis, wherein said second object is fixedly placed in line with said optical axis, wherein said second object is located between, and spaced from, (i) said first object and (ii) said image plane, wherein said second object is configured to impart a second pattern on said beam and wherein said optical element is fixedly placed in line with said optical axis and located between and spaced from (i) said second object and (ii) said image plane, wherein said optical element is configured to simultaneously form an image of said first pattern and an image of said second pattern at said image plane;
imparting a first pattern to said beam of light to produce a patterned beam, wherein said first pattern is imparted with said first object;
imparting a second pattern to said patterned beam to produce a combined patterned beam, wherein said second pattern is imparted with said second object;
imaging said combined patterned beam to a single plane to produce an imaged combined patterned beam, wherein said combined pattern beam is imaged with said optical element; and
capturing said imaged combined patterned beam with a single detector to produce a captured imaged beam.
2. The method of claim 1 , wherein said first object is selected from the group consisting of a mask, a spatial pattern., a spatial light modulator, an array of micro-electro-mechanical systems detector elements and liquid crystals.
3. The method of claim 1 , wherein said second object is selected from the group consisting of a mask, a spatial pattern, a spatial light modulator, an array of micro-electro-mechanical systems detector elements and liquid crystals.
4. The method of claim 1 , wherein said optical element comprises a catadioptric lens.
5. The method of claim 1 , wherein said first pattern and said second pattern each comprises a coherent pattern such that said combined patterned beam comprises an interference pattern.
6. The method of claim 1 , wherein at least one of said first pattern and said second pattern comprise at least one of a phase pattern and an amplitude pattern.
7. The method of claim 1 , wherein said detector comprises a camera.
8. The method of claim 7 , wherein said camera is selected from the group consisting of a video camera and a multi-pixel detector.
9. The method of claim 1 , further comprising temporally modulating at least one of said first pattern and said second pattern.
10. The method of claim 1 , further comprising processing said captured imaged beam to produce processed data, the method further comprising altering the direction of propagation of said beam to a direction that is selected from the group consisting a better centering of said beam on said optical axis and a better pointing of said beam to the point where said beam terminates at said image plane.
11. The method of claim 1 , further comprising gating at least one of said first pattern and said second pattern.
12. An apparatus, comprising:
a first object for imparting a first pattern to an input beam of light to produce a patterned beam, wherein said first object is fixedly placed on an optical axis, wherein said first object is configured to impart said first pattern on said input beam as it propagates on or about said optical axis;
a second object for imparting a second pattern to said patterned beam to produce a combined patterned beam, wherein said second object is fixedly placed on said optical axis and is located between, and spaced from, (i) said first object and (ii) an image plane located on said optical axis, wherein said second object is configured to impart said second pattern to said patterned beam;
an optical element configured for imaging said combined patterned beam onto said image plane to produce an imaged combined patterned beam, wherein said optical element is fixedly placed on said optical axis and is located between, and spaced from, (i) said second object and (ii) said image plane, wherein said optical element is configured to simultaneously form an image of said first pattern and an image of said second pattern at said image plane; and
a detector for capturing said imaged combined patterned beam to produce a captured imaged beam.
13. The apparatus of claim 12 , wherein said first object is located a positive distance from said second object.
14. The apparatus of claim 12 , wherein said first object is selected from the group consisting of a mask, a spatial pattern, a spatial light modulator, an array of micro-electro-mechanical systems detector elements and liquid crystals.
15. The apparatus of claim 12 , wherein said second object is selected from the group consisting of a mask, a spatial pattern, a spatial light modulator, an array of micro-electro-mechanical systems detector elements and liquid crystals.
16. The apparatus of claim 12 , wherein said optical element comprises a catadioptric lens.
17. The apparatus of claim 12 , wherein said deector comprises a multi-pixel detector.
18. The apparatus of claim 12 , further comprising means for gating at least one of said means for imparting a first pattern and said means for imparting a second pattern.
19. The apparatus of claim 12 , further comprising means for temporally modulating at least one of said first pattern and said second pattern.
20. The apparatus of claim 12 , further comprising means for processing said captured imaged beam to produce processed data, the apparatus further comprising means for adjusting at least one of said first pattern and said second pattern.
21. An apparatus, comprising:
an optical axis terminating at an image plane;
a first object fixedly placed on said optical axis, wherein said first object is configured to impart a first pattern at said first object on a beam propagating on said optical axis toward said image plane;
a second object fixedly placed on said optical axis, wherein said second object is located between and spaced from said first object and said image plane, wherein said second object is configured to impart a second pattern at said second object on said beam; and
a lens fixedly placed on said optical axis and located between and spaced from said second object and said image plane, wherein said lens is configured to form an image of said first pattern and an image of said second pattern at said image plane.
22. A method, comprising:
directing a beam of light on or about an optical axis that terminates at an image plane, wherein said beam passes through a first object and then a second object and then an optical element before propagating onto said image plane;
wherein said first object is fixedly placed on said optical axis, wherein said first object is configured to impart a first pattern on said beam as it propagates on said optical axis;
wherein said second object is fixedly placed on said optical axis, wherein said second object is located between, and spaced from, said first object and said image plane, wherein said second object is configured to impart a second pattern on said beam; and
wherein said optical element is fixedly placed on said optical axis and located between and spaced from said second object and said image plane, wherein said optical element is configured to simultaneously form an image of said first pattern and an image of said second pattern at said image plane.