Method and systems are presented for analysing a wavefront using a spectral wavefront analyser to extract optical phase and spectral information at a two dimensional array of sampling points across the wavefront, wherein the relative phase information between the sampling points is maintained. Methods and systems are also presented for measuring an eye by reflecting a wavefront of an eye and measuring the wavefront at a plurality of angles to provide a map of the off-axis relative wavefront curvature and aberration of the eye. The phase accuracy between wavelengths and sample points over a beam aperture offered by these methods and systems have a number of ocular applications including corneal and anterior eye tomography, high resolution retinal imaging, and wavefront analysis as a function of probe beam incident angle for determining myopia progression and for designing and testing lenses for correcting myopia.

In a spherical shape measurement method for measuring a surface shape, a sphere to be measured is made freely rotatable. The partial spherical shape of each measurement area, which is established so as to have an area overlapping with another measurement area adjacent to each other, is measured at each rotation position, and the surface shape is measured by joining the partial spherical shapes of the measurement areas by a stitching operation based on the shape of the overlapping area. In the state of detaching the sphere from the sphere hold mechanism to which the sphere is freely attachable and detachable, the sphere support table holds the sphere. The sphere is re-held at a different position, so that the shape of the entire sphere can be measured with high accuracy.

The invention relates to a method for determining the distance to a movable target object and/or the position of said movable target object and comprises the steps of directing a coherent, focused measurement beam at the spherical target object, which has a convex reflective surface, in such a way that the center of the target object lies at the focus of the measurement beam, and determining a distance between the target object and a reference point by interferometrically superposing the measurement beam reflected by the target object with a reference beam.

Method for measuring a spherical-astigmatic optical surface (40), includes: a) generating a spherical-astigmatic wavefront as a test wavefront with a wavefront generating apparatus (10); b) interferometrically measuring wavefront aberrations between the wavefront generating apparatus and the surface which is adjusted to the wavefront generating apparatus such that the test wavefront impinges each point on the surface substantially perpendicularly, plural measurements being taken in which the surface is measured at a number of positions, spherized about the two centers of the radii of the astigmatism and/or rotated by 180 about a surface normal to the surface, such that corresponding interferogram phases are determined; and c) determining the wavefront of the wavefront generation device and a shape of the surface using a mathematical reconstruction method. The spherical-astigmatic surface is then corrected using a suitable processing method, a) to c) being repeated until the wavefront aberrations are smaller than a given value.

A measurement apparatus (10) for determining a shape of an optical surface. An illumination module (16) produces an illumination wave (34), an interferometer (18) splits the wave into a test wave (50), which is directed onto the optical surface, and a reference wave (52). The relative tilt between the waves produces a multi-fringe interference pattern (66) in a detection plane (62) of the interferometer when the waves are superposed. A pupil plane (28) of the illumination module is arranged in a Fourier plane of the detection plane and the illumination module is configured to produce the illumination wave so that the intensity distribution thereof in the pupil plane includes at least one spatially isolated and contiguous surface region (38) such that a rectangle (74) with the smallest possible area fitted to the surface region or the totality of surface regions has an aspect ratio of at least 1.5:1.

An analytic tool for supporting alignment of an optical component in preparation for an interferometric test and performance of such a test. Apparatus and methods involve employment of the datum features on the optical component and/or metrology frame supporting such component. The metrology frame may include a secondary set of holograms (provided for use with a conventional system already employing a primary hologram that forms the testing optical wavefront). The conventional primary hologram is preferably substituted with a set of primary holograms (contained in the same, unitary or spatially-complementary housing sets) that perform different but complementary functions and that facilitate the alignment of the metrology frame with or without the tested optical component.

An interferometer for areally measuring an optically smooth surface is presented, including means for illuminating a surface region with a plurality of discrete object waves from different directions and comprising means which, on a detector, superimpose object waves reflected at the surface onto a reference wave that is coherent with a plurality of object waves in order to form an interferogram. The interferometer is distinguished by virtue of it being configured to illuminate the surface with a plurality of object waves at the same time and produce the reference wave by way of a Fizeau beam splitter plate or a Fizeau objective, and by virtue of the interferometer including an interferometer stop that is arranged in the beam path upstream of the detector, and imaging optics, wherein the interferometer stop is situated within, or slightly outside of, the Fourier plane of the imaging optics and said interferometer stop filters the object waves reflected by the surface.

Methods, apparatus and systems for testing an optical element are described. One example device for measuring a test optical component includes a pre-conditioning optical module positioned to receive an optical beam from a light source and to produce a beam having a non-collimated beam profile or a freeform wavefront. The device further includes a beam splitter positioned to receive the beam output from the pre-conditioning optical module and to direct a first portion of the beam to a reference arm configured to accommodate a reference optical component, and to direct a second portion of the beam to a test arm configured to accommodate the test optical component. The device also includes a beam combiner positioned to receive the beams from the reference arm and the test arm after reflection or refraction by the reference and the test optical components.

An analytic tool for supporting alignment of an optical component in preparation for an interferometric test and performance of such a test. Apparatus and methods involve employment of the datum features on the optical component and/or metrology frame supporting such component. The metrology frame may include a secondary set of holograms (provided for use with a conventional system already employing a primary hologram that forms the testing optical wavefront). The conventional primary hologram is preferably substituted with a set of primary holograms (contained in the same, unitary or spatially-complementary housing sets) that perform different but complementary functions and that facilitate the alignment of the metrology frame with or without the tested optical component.

Method and systems are presented for analysing a wavefront using a spectral wavefront analyser to extract optical phase and spectral information at a two dimensional array of sampling points across the wavefront, wherein the relative phase information between the sampling points is maintained. Methods and systems are also presented for measuring an eye by reflecting a wavefront of an eye and measuring the wavefront at a plurality of angles to provide a map of the off-axis relative wavefront curvature and aberration of the eye. The phase accuracy between wavelengths and sample points over a beam aperture offered by these methods and systems have a number of ocular applications including corneal and anterior eye tomography, high resolution retinal imaging, and wavefront analysis as a function of probe beam incident angle for determining myopia progression and for designing and testing lenses for correcting myopia.