A measurement arrangement (10) and an associated method for interferometrically determining the surface shape (12) of a test object (14) includes a light source (16) providing an input wave (18) and a diffractive optical element (24). The diffractive optical element is configured to produce in each case by way of diffraction from the input wave a test wave (26), which is directed at the test object (14) and has a wavefront that is adapted at least partially to a desired shape of the optical surface, and a reference wave (28). The measurement arrangement furthermore includes a reflective optical element (30) that back-reflects the reference wave (28) and a capture device (36) that captures an interferogram produced by superposing the test wave after interaction with the test object and the back-reflected reference wave (28), in each case after a further diffraction at the diffractive optical element in a capture plane (48).

Some embodiments of the present inventive concept provide optical coherence tomography (OCT) systems for integration with a microscope. The OCT system includes a sample arm coupled to the imaging path of a microscope. The sample arm includes an input beam zoom assembly including at least two movable lenses configured to provide shape control for an OCT signal beam; a scan assembly including at least one scanning mirror and configured for telecentric scanning of the OCT signal beam; and a beam expander configured to set the OCT signal beam diameter incident on the microscope objective. The shape control includes separable controls for numerical aperture and focal position of the imaged OCT beam.

Method and systems are presented for analyzing a wavefront using a spectral wavefront analyzer 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.

Interferometry-based methods and apparatus are presented for analyzing one or more wavefronts from a sample, in which the sample wavefronts are interfered with two or more reference wavefronts to produce two or more interferograms in a sufficiently short time period for the interferograms to be captured in a single exposure of an image capture device such as a CCD array. Each interferogram has a unique carrier frequency dependent on the angle between a respective pair of sample and reference wavefronts. In certain embodiments multiple sample and/or reference wavefronts are generated using scanning mirrors, while in other embodiments utilizing multi-wavelength beams multiple sample and/or reference wavefronts are generated with wavelength dispersive elements. The methods and apparatus are suitable for measuring aberrations at one or more positions on the retina of an eye.

A measuring apparatus (10; 110; 210; 310; 410; 510; 610; 710) for interferometric determination of a property (50; 52) of a shape (50) of a test surface (12) of an object under test (14) comprises an irradiation device (22) for generating an input wave (24), a splitting module (18; 118; 318; 418; 518) configured to generate, from the input wave, two plane waves (32, 34) with parallel directions of propagation and with an offset from one another across the directions of propagation, a wavefront adaptation module (20; 720) for generating two measurement waves (44, 46) by adapting the respective wavefront of the plane waves with an offset from one another to a target shape of the optical test surface, and a detector (56) for capturing at least one interferogram (64) generated by superposition of the measurement waves (44r, 46r) following their interaction with the test surface.

In a method for characterizing the surface shape, the following steps are carried out iteratively: (A) calculating a first figure based on first measurements; (B) subtracting the first figure from first measured values, to determine a first test set-up error; (C) using the first test set-up error for calculating a corrected first figure,; (D) subtracting the corrected first figure from second measured values, to determine a second test set-up error; (E) using the second test set-up error for calculating a corrected second figure; (F) using the corrected second figure for correcting the first test set-up error by subtracting the corrected second figure from the first measured values, to determine a corrected first test set-up error; (G) using the corrected first test set-up error for calculating a first figure corrected once again; and (H) comparing the result with a convergence criterion and optionally repeating steps (A) to (H).

Measurement method for interferometrically determining a shape of a test object (14) surface (12) includes arranging a first diffractive optical element (30, 130, 230) in an input wave (18) beam path, to generate a first test wave (34) with a wavefront that is adapted to a desired shape of the optical surface, detecting a first interferogram generated by the first test wave after interaction with the test object surface, arranging a different diffractive optical element (32, 232) in the input wave beam path for generating a further test wave with a wavefront which is adapted to the desired shape of the optical surface, the first and the further diffractive optical elements differing in their respective diffraction structure configurations, capturing a further interferogram generated by the further test wave after interaction with the test object surface, and determining the surface shape of the test object by calculating the two interferograms.

An apparatus that measures a position of a test surface in an optical system, includes a standard unit including a standard surface, an interferometer including a light source that emits test light and reference light and a detector that acquires a first signal and a second signal, an adjustment unit configured to adjust intensity of at least one of the first signal and the second signal, and a computing unit configured to calculate the position of the test surface based on the first signal and the second signal, wherein the first signal is a signal generated by interference between the reference light and standard light that is the test light being reflected from the standard surface, and wherein the second signal is a signal generated by interference between the reference light and measurement light that is the test light being reflected from the test surface.

A method for measuring a surface shape of an optical element, wherein the optical element has a main body with a substrate and a reflective surface, and wherein at least one cooling channel for receiving a coolant is formed in the substrate, comprising: a) recording a cooling channel pressure, b) recording a measurement environment pressure, c) determining a pressure difference based on the cooling channel pressure and the measurement environment pressure, d) comparing the pressure difference with a predetermined target pressure difference, e) monitoring for a deviation between the pressure difference and the target pressure difference, wherein, if a deviation greater than a predetermined limit value is detected, the cooling channel pressure is adapted in such a way that the deviation becomes less than or equal to the predetermined limit value, and f) measuring the surface shape if the deviation is less than or equal to the predetermined limit value.

An interferometer for the measurement of a surface or an optical thickness of an optically smooth test object is provided, wherein the interferometer is configured to illuminate the optically smooth test object simultaneously with a plurality of object waves, which have different wavelengths from one another, and to superimpose the object waves deformed by the illuminated test object onto coherent reference waves on an image capture device, and to spectrally decompose the interferograms resulting from the superposition into wavelength-specific partial interferograms.