Optical apparatus
AssigneeWavesense Engineering GmbH
InventorAbhishek Kumar
Life of this patent
Estimating the term…
Abstract
An optical apparatus is comprising an optical imaging arrangement generating either an image of the original object field or the field of the original sample at the pupil plane which consist of both amplitude and phase information. The apparatus is further comprising a digital adaptive optics arrangement with a wave front sensor and a computing unit, which is adapted to generate at least one orthogonally translated digital copy of the original sample object field at the spatial Fourier or pupil plane and to analytically calculate a wave front error based on the phase difference between the original sample wave front and its digital copy or copies.
Claims20
An interferometric apparatus to image a point on a sample, comprising:
- an optical arrangement configured to produce a sample beam and a reference beam and to produce either 1) an image of an original object field of the point at an image plane illuminated by the sample beam, the field including both amplitude information and phase information or 2) a field of the point at a pupil plane when the point is illuminated by the sample beam, the field including both amplitude information and phase information, the optical arrangement configured to produce a combination of the sample beam after illumination of the point and the reference beam;
- a scanner located to receive the combination of the sample beam and reference beam and to direct the combination through focusing optics and onto a pinhole filter, the scanner and focusing optics being arranged to translate overlapping spots corresponding to the reference beam and the sample beam across the pinhole filter,
- a photodetector located to receive light from the combination passing through the pinhole filter as the overlapping spots translate across the pinhole filter thereby determining a point spread function of the apparatus;
- and
- a digital adaptive optics arrangement comprising:
- (i.) a wavefront sensor configured to calculate (1) a sampled wavefront of the original object field of the point at the image plane or (2) a sampled wavefront of the object field of the point at the pupil plane, using the point spread function;
- and
- (ii.) a computing unit adapted to:
- A) generate at least one digital shifted copy of the sampled wavefront of the object at the pupil plane by
- (1) using the image of the original object field of the point at the image plane to calculate the field at the pupil plane and shifting the calculated field along a horizontal or a vertical direction or an axis of a defined coordinate system of the pupil plane or
- (2) using the field of the point at the pupil plane and shifting the field along a horizontal or a vertical direction or an axis of a defined coordinate system of the pupil plane and
- B) determine a wavefront error in the original object field based on a phase difference between (1) a sampled wavefront of the calculated and the at least one digital shifted copy at the pupil plane or (2) the sampled wavefront of the object field of the point at the pupil plane and the at least one digital shifted copy at the pupil plane.
A non-transitory computer readable medium having executable programming instructions stored thereon comprising program code for:
- generating at least one laterally translated digital copy of an original object field of an optical apparatus at a spatial Fourier plane along the horizontal or vertical direction or axis of a defined coordinate system of the pupil plane;
- and
- determining a wavefront error based on a phase difference between an original wavefront and a digital copy or copies of the original wavefront.
Dependencies are inferred from the claim text.