Two grating lateral shearing wavefront sensor
AssigneeZygo Corporation
InventorMichael Küchel
Life of this patent
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Abstract
Methods include simultaneously diffracting a beam in a first direction and a second direction orthogonal to the first direction to form a once-diffracted beam, where the beam comprises a wavefront shaped by a test object, simultaneously diffracting the once-diffracted beam in orthogonal directions to form a twice-diffracted beam, overlapping at least two orders of the twice-diffracted beam in each direction to form an interference pattern at a detector, the interference pattern being formed by multiple copies of the wavefront laterally sheared in the first direction and multiple copies of the wavefront laterally sheared in the second direction; and determining information about the wavefront based on the interference pattern.
Claims41
A method, comprising:
- simultaneously diffracting a beam in a first direction and a second direction orthogonal to the first direction to form a once-diffracted beam, where the beam comprises a wavefront shaped by a test object;
- simultaneously diffracting the once-diffracted beam in orthogonal directions to form a twice-diffracted beam,
- overlapping at least two orders of the twice-diffracted beam in each direction to form an interference pattern at a detector, the interference pattern being formed by multiple copies of the wavefront laterally sheared in the first direction and multiple copies of the wavefront laterally sheared in the second direction;
- and
- determining information about the wavefront based on the interference pattern.
An apparatus, comprising:
- a first grating, periodic in a first direction and a second direction orthogonal to the first direction, positioned along an optical axis to diffract a beam from a test object in the first and second directions, the beam comprising a wavefront shaped by the test object;
- a second grating, periodic in two orthogonal directions, positioned to receive the once-diffracted beam from the first grating and diffract the once-diffracted beam in the two orthogonal directions;
- a detector positioned to receive at least two orders of the twice-diffracted beam in the first and second directions forming an interference pattern at the detector, the interference pattern being formed by multiple copies of the wavefront laterally sheared in the first direction and multiple copies of the wavefront laterally sheared in the second direction;
- and
- an electronic processor in communication with the detector and configured to determine information about the wavefront based on the interference pattern.
Dependencies are inferred from the claim text.