A measuring device (10) for the interferometric shape measurement of a surface (12) of a test object (14-1; 14-2)includes (i) a diffractive optical element (26-1; 26-2) that generates a test wave (28) from incoming measurement radiation (18), wherein the diffractive optical element radiates the test wave onto the surface of the test object, (ii) a deflection element (22) that is disposed upstream of the diffractive optical element in the beam path of the measurement radiation, and (iii) a holding device (24, 124) that holds the deflection element and that changes a position of the deflection element (22) through a combination of a tilting movement and a translation movement.

A full-field optical coherence tomography imaging method, FFOCT, using a system comprising an FFOCT device and a sample, the sample comprising a layer of interest to be imaged, the FFOCT device comprising an incoherent light source, an imager, a beam splitter defining a sample arm and a reference arm, the method comprising-generating sample light containing interest light originating from the layer of interest and reference light traveling from the reference arm, —acquiring an image from reference light and sample light combined in the beam splitter; wherein at least one of the sample arm and the reference arm comprises an optical curvature compensator that modifies a transverse variation distribution of an optical path length to match the transverse variation distributions of the optical path lengths travelled by the reference light and the interest light incident on the imager.

A measurement apparatus for interferometric shape measurement of a test object surface. A test optical unit produces from measurement radiation a test wave for irradiating the surface. A reference element with an optically effective surface interacts with a reference wave also produced from the measurement radiation. An interferogram is produced by superimposing the test wave after interaction with the test object's surface. A holding device holds the reference element and moves the reference element relative to the reference wave in at least two rigid body degrees of freedom so that a peripheral point of the reference element's optically effective surface shifts by at least 0.1% of a diameter of the optically effective surface. The at least two degrees of freedom include a translational degree, directed transversely to a propagation direction of the reference wave and a rotational degree, whose rotational axis aligns substantially parallel to the reference wave's propagation direction.

A low-coherence Fizeau interferometer includes a first beamsplitter, a test arm and a reference arm, the first beamsplitter splits light into a first portion of light directed to the test arm and a second portion of light directed to the reference arm, and an imaging arm comprising a first collimating lens, a flat reference surface, and a test element. The test arm focuses the first portion of light at a first focal point, such that a virtual image of the first focal point appears at a focal point of the test element. The reference arm focuses the second portion of light at a second focal point, the first collimating lens collimates the light that then reflects off the flat reference surface. The second beamsplitter directs the first portion of light to reflect off the test element. The reflection of the first and second portion of light form an interference pattern.

An optical device for characterizing a workpiece combines an interferometer with a polarization rotation pellicle, installed in a stand-alone fashion in a spatial gap between the mirrors of the interferometer, and a polarization based phase-shift sensor.

A measurement method for interferometrically measuring the shape of a surface (112) of a test object (114). A test wave (125-1, 125-2) directed at the test object has a wavefront that is at least partially adapted to the desired shape of the surface, and a reference wave (128-1, 128-2) directed at a reflective optical element (130-1, 130 2) has a propagation direction that deviates from the propagation direction of the test wave (125-1, 125-2) for each of two input waves by diffraction at a diffractive element (124). For each wavelength, the test wave is superimposed after interaction with the test object with the associated reference wave after the back-reflection at the first reflective optical element. The test and reference waves are diffracted again at the diffractive element for superposition. An interferogram produced by the superposition is captured in a capture plane (148-1, 148-2). The interferograms are jointly evaluated.

Methods for characterizing the surface shapes of optical elements include the following steps: carrying out, in an interferometric test arrangement, at least a first interferogram measurement on the optical element by superimposing a test wave, which has been generated by diffraction of electromagnetic radiation on a diffractive element and has been reflected at the optical element, carrying out at least one additional interferogram measurement on in each case one calibrating mirror for determining calibration corrections, and determining the deviation from the target shape of the optical element based on the first interferogram measurement carried out on the optical element and the determined calibration corrections. At least two interferogram measurements are carried out for the at least one calibrating mirror, which differ from one another with regard to the polarization state of the electromagnetic radiation.

A compensation optical unit (30) for a measurement system (10) for determining a shape of an optical surface (12) of a test object (14) by interferometry generates a measuring wave (44), directed at the test object, with a wavefront that is at least partly adapted to a target shape of the optical surface from an input wave (18). The unit includes first (32) and second (34) optical elements disposed in a beam path of the input wave. The second optical element is a diffractive optical element configured to split the input wave into the measuring wave and a reference wave (42) following an interaction with the first optical element. At least 20% of a refractive power of the entire compensation optical unit is allotted to the first optical element, and this allotted refractive power has the same sign as the refractive power of the entire compensation optical unit.

A device and a method for characterizing the surface shape of a test object. The device for characterizing the surface shape of a test object has a test arrangement (130, 230) for determining the surface shape of a test object (111, 112, 113, 211, 212, 213) using a test wave. The test wave has a wavefront generated by diffraction at a diffractive optical element. The device additionally has a first vacuum chamber (110, 210) and a second vacuum chamber (120, 220), wherein the second vacuum chamber (120, 220) has a magazine for mounting at least two diffractive optical elements (121, 122, 123, 221, 222, 223).

A method for calibrating a measuring device (10) for interferometrically determining a shape of an optical surface (12) of an object under test (14). The measuring device includes a module plane (32) for arranging a diffractive optical test module (30) which is configured to generate a test wave (34) that is directed at the optical surface and that has a wavefront at least approximately adapted to a target shape (60) of the optical surface. The method includes: arranging a diffractive optical calibration module (44) in the module plane for generating a calibration wave (80), acquiring a calibration interferogram (88) generated using the calibration wave in a detector plane (43) of the measuring device, and determining a position assignment distribution (46) of points (52) in the module plane to corresponding points (54) in the detector plane from the acquired calibration interferogram.