Interferometer optical element alignment
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Abstract
A method for aligning an optical element of an optical interferometer in which a beam of light interacts with the optical element and the optical element is tilted about first and second axes to adjust the relative phase of components of the beam. At least three parallel alignment beams of monochromatic light are directed through the interferometer towards respective detectors. The detectors are arranged in pairs such that tilting the optical element about the first axis does not affect the relative phase of components of each of the beams directed towards a first pair of detectors and tilting the optical element about the second axis does not affect the relative phase of components of each of the beams directed towards the second pair of detectors. One detector may form part of each of the first and second pairs of detectors. A first estimate of an aligned optical element position is derived by determining from an output of at least one detector a first element position at which the magnitude of the beam incident on that detector is a maximum. Second estimates of aligned element positions are also derived by determining second element positions at which the phase differences between beams incident on each of the pairs of detectors are a minimum. The element is aligned by moving it to a final position which is one of the second positions which is at or adjacent the first position. A set of second element positions may be determined, the element being moved to each of the set of second element positions in turn. The magnitude of outputs of at least one of the detectors may then be monitored at each of the second element positions to which the element is moved, and the element may be moved to the final position which corresponds to the position at which the monitored magnitude is a maximum.
16 Citations
25 Claims
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1. (canceled)
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12. An apparatus for aligning an optical element of an optical interferometer, comprising
means for directing at least three alignment beams of monochromatic light through the optical interferometer towards respective detectors, the detectors being arranged in pairs where tilting the optical element about a first axis affects a relative phase of components of each of the alignment beams directed towards a first pair of detectors in a predetermined manner, and tilting the optical element about a second axis affects a relative phase of components of each of the alignment beams directed towards a second pair of detectors in a predetermined manner; -
means for deriving a first estimate of an aligned optical element position by determining from an output of at least one detector a first element position at which a magnitude of the beam incident on the at least one detector is a maximum;
means for deriving second estimates of aligned element positions by determining second element positions at which predetermined phase differences between the at least three alignment beams incident on each of the pairs of detectors are established; and
means for aligning the optical element by moving it to a final position which is one of the second positions which is at or adjacent the first position. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for aligning an optical element of an optical interferometer, comprising:
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directing at least three alignment beams of monochromatic light through respective detectors, the detectors being arranged in pairs such that tilting the optical element about a first axis affects a relative phase of components of each of the beams directed toward a first pair of detectors in a predetermined manner and tilting the optical element about the second axis affects the relative phase of components of each of the beams directed towards the second pair of detectors in a predetermined manner;
deriving a first estimate of an aligned optical element position by determining from an output of at least one detector a first element position at which a magnitude of the beam incident on that detector is a maximum;
deriving second estimates of aligned element positions by determining second element positions at which predetermined phase differences between beams incident on each of the pairs of detectors are established; and
aligning the optical element by moving the optical element to a final position which is one of the second positions that is at or adjacent the first position - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification