Beam alignment system

• US 4,319,839 A
• Filed: 03/27/1980
• Issued: 03/16/1982
• Est. Priority Date: 03/27/1980
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Durran, Donald A.
• Primary Examiner(s): Punter, William H.
• Application Number:
  US06/134,597
• Time in Patent Office: 719 Days
• Field of Search: 356/138, 356/153, 356/152, 356/147-148, 356/399-400, 219/121 LS, 219/121 LU, 219/121 LW, 219/121 LM, 346/76 L, 250/202-203, 358/285, 358/293, 350/6.1-6.91, 350/171
• US Class Current: 356/153
• CPC Class Codes: G01B 11/272 using photoelectric detection means

Abstract

A beam alignment system having a source for producing a first beam of electromagnetic radiation considered an alignment or reference beam, a source for producing a second beam of electromagnetic radiation to be aligned with the first beam and pair of rotating mirrors capable of being optically interposed at different times across the optical path of the first and second beams. The axes of rotation of the pair of mirrors are transverse to each other in order to enable each mirror to provide alignment information about the beams with respect to two different planes. The alignment information is indicative of a time difference between the reception by a first detector of the reflected first beam and the reflected second beam from the first mirror and a time difference between the reception by a second detector of the reflected first beam and the reflected second beam from the second mirror. These time differences are utilized to provide signals which are used to adjust the position of the source for the second beam in order to bring the second beam into alignment with the first beam in two different planes.

Claims

1. A beam alignment system comprising a first reflective element, means for rotating said first reflective element about a first axis, a second reflective element, means for rotating said second reflective element about a second axis, said first axis and said second axis being positioned at right angles to each other, said first reflective element being rotatable through a first preselected position at a first preselected time so as to intercept the optical path of a first beam of electromagnetic radiation and a second beam of electromagnetic radiation to be aligned with said first beam, said first reflective element reflecting said first and second beams therefrom, said second reflective element being rotatable through a second preselected position at a second preselected time so as to intercept the optical path of said first beam and said second beam, said second reflective element reflecting said first and said second beams therefrom, said first and said second reflecting means being so positioned with respect to each other so as to intersect said optical path of said first and said second beams at different times and wherein said optical path of said first and second beams is generally unoccluded as said beams pass through said system except during said first preselected time and said second preselected time, first means optically aligned with said first reflective element for detecting said first and said second beams reflected from said first reflective element and producing a first signal in response thereto, said first signal being indicative of a time interval between the reception by said first detecting means of said first reflected beam and said second reflected beam, whereby said first signal is representative of any misalignment between said first beam and said second beam in a first plane, second means optically aligned with said second reflective element for detecting said first and said second beams reflected from said second reflective element and producing a second signal in response thereto, said second signal being indicative of a time interval between the reception by said second detecting means of said first reflected beam and said second reflected beam, whereby said second signal is representative of any misalignment between said first beam and said second beam in a second plane.

2. A beam alignment system as defined in claim 1 wherein said first detecting means comprises a photodetector and a slit optically aligned therewith, said slit of said first photodetector being aligned along a first longitudinal axis, and said second detecting means comprising a photodetector and a slit optically aligned therewith, said slit of said second photodetector being aligned along a second longitudinal axis, said first and second longitudinal axes being transverse to one another.

3. A beam alignment system as defined in claim 1 wherein said first reflective element is part of a first reflector assembly and said second reflective element is part of a second reflective assembly, said first and second reflective assemblies being operably connected together in order to provide synchronous rotation of said first and said second reflective elements.

4. A beam alignment system comprising means for producing a first beam of electromagnetic radiation, means for producing a second beam of electromagnetic radiation to be aligned with said first beam, means in optical alignment with said first beam and said second beam for receiving said first and said second beams and providing a first signal indicative of a time interval between reception of said first beam and said second beam in a first plane and a second signal indicative of a time interval between reception of said first beam and said second beam in a second plane, said receiving and signal providing means including a first reflective element, means for rotating said first reflective element about a first axis, a second reflective element, means for rotating said second reflective element about a second axis, said first axis and said second axis being positioned at right angles to each other, said first reflective element being rotatable through a first preselected position at a first preselected time so as to intercept the optical path of said first beam and said second beam, said first reflective element reflecting said first and said second beams therefrom, said second reflective element being rotatable through a second preselected position at a second preselected time so as to intercept the optical path of said first beam and said second beam, said second reflective element reflecting said first and said second beams therefrom, said first and said second reflecting elements being so positioned with respect to each other so as to intersect said optical path of said first and said second beams at different times and wherein said optical path of said first and second beams is generally unoccluded as said beams pass through said system except during said first preselected time and said second preselected time, first means optically aligned with said first reflective element for detecting said first and said second reflected beams and producing said first signal in response thereto, second means optically aligned with said second reflective element for detecting said first and said second beams reflected therefrom and producing said second signal in response thereto whereby said first signal is representative of a misalignment between said first beam and said second beam in said first plane, and said second signal is representative of a misalignment between said first beam and said second beam in said second plane, means connected to said means for producing said second beam for adjusting the position of said second beam producing means in said first plane and said second plane, and means operably connected between said adjusting means and said receiving and signal providing means for transferring said first and said second signals to said adjusting means whereby said adjusting means adjusts the position of said second beam producing means in accordance therewith in order to provide alignment between said first beam and said second beam.

5. A beam alignment system as defined in claim 4 wherein said first detecting means comprises a photodetector and a slit optically aligned therewith, said slit of said first photodetector being aligned along a first longitudinal axis, and said second detecting means comprises a photodetector and a slit optically aligned therewith, said slit of said second photodetector being aligned along a second longitudinal axis, said first and second longitudinal axes being transverse to one another.

6. A beam alignment system as defined in claim 4 wherein said first reflective element is part of a first reflector assembly and said second reflective element is part of a second reflective assembly, said first and second reflective assemblies being operably connected together in order to provide synchronous rotation of said first and said second reflective elements.