A method for determining geometrical parameters of a soft contact lens comprises the steps of providing an OCT imaging device comprising an OCT light source; providing a soft contact lens arranging the soft contact lens relative to the OCT imaging device so light coming from the OCT light source impinges on the back surface of the soft contact lens; generating a three-dimensional OCT image of the soft contact lens; from the three-dimensional OCT image determining a plurality of edge points located on the edge of the soft contact lens, connecting adjacent ones of the edge points by individual straight lines; summing up the lengths of all individual straight lines to a length U of the approximated circumference of the soft contact lens; from the length U determining a diameter D of the lens according to D=U/π.

System and methods are provided for characterizing an internal surface of a lens using interferometry measurements. Sphere-fitting a distorted radius determines distorted pathlengths. Ray-tracing simulates refraction at all upstream surfaces to determine a cumulative path length. A residual pathlength is scaled by the group-index and rays are propagated based on the phase-index. After aspheric surface fitting, a corrected radius is determined. To estimate a glass type for the lens, a thickness between focal planes of the lens surfaces is determined using RCM measurements. Then, for both surfaces, the surface is positioned into focus, interferometer path length matching is performed, a reference arm is translated to stationary phase point positions for three wavelengths to determine three per-color optical thicknesses, and ray-tracing is performed. A glass type is identified by minimizing an error function based on optical parameters of the lens and parameters determined from known glass types from a database.

A measurement device, for measuring the shape of an interface to be measured of an optical element having a plurality of interfaces, the device including: measurement apparatus with at least one interferometric sensor illuminated by a low-coherence source, for directing a measurement beam towards the optical element to pass through the plurality of interfaces, and to detect an interference signal resulting from interferences between the measured measurement beam reflected by the interface and a reference beam; positioning apparatus configured for relative positioning of a coherence area of the interferometric sensor at the level of the interface to be measured; digital processor for producing, based on the interference signal, an item of shape information of the interface to be measured according to a field of view.

A measurement method, for measuring the shape of an interface of an optical element having a plurality of interfaces is also provided.

A workpiece holder is configured to hold a workpiece and is utilized in a metrology system which includes a sensing configuration for obtaining 3-dimensional surface data for the workpiece. The workpiece holder includes at least three reference features (e.g., spherical reference features extending from sides) that are configured to be sensed by the sensing configuration when the workpiece holder is in different orientations (e.g., as rotated 180 degrees between first and second orientations for presenting front and back sides of the workpiece towards the sensing configuration). A determination of 3-dimensional positions of the reference features for each orientation enables a combining (e.g., in a common coordinate system) of 3-dimensional surface data that is acquired for the workpiece in each orientation. Interchangeable workpiece holding portions may be provided that fit within the workpiece holder for holding workpieces with different characteristics (e.g., having different sizes and/or shapes).

A multi-core fiber includes multiple optical cores, and for each different core of a set of different cores of the multiple optical cores, a total change in optical length is detected. The total change in optical length represents an accumulation of all changes in optical length for multiple segments of that different core up to a point on the multi-core fiber. A difference is determined between the total changes in optical length for cores of the set of different cores. A twist parameter and/or a bend angle associated with the multi-core fiber at the point on the multi-core fiber is/are determined based on the difference.

A workpiece holder is configured to hold a workpiece and is utilized in a metrology system which includes a sensing configuration for obtaining 3-dimensional surface data for the workpiece. The workpiece holder includes at least three reference features (e.g., spherical reference features extending from sides) that are configured to be sensed by the sensing configuration when the workpiece holder is in different orientations (e.g., as rotated 180 degrees between first and second orientations for presenting front and back sides of the workpiece towards the sensing configuration). A determination of 3-dimensional positions of the reference features for each orientation enables a combining (e.g., in a common coordinate system) of 3-dimensional surface data that is acquired for the workpiece in each orientation. Interchangeable workpiece holding portions may be provided that fit within the workpiece holder for holding workpieces with different characteristics (e.g., having different sizes and/or shapes).

A metrological apparatus (15) is disposed for adjustment of an attitude of a workpiece (16) having an arcuate upper surface (17) relative to a rotary axis (C) of the metrological apparatus (15). The workpiece (16) is brought into a first rotary position (c1). A plurality of measured points within a measuring plane on the upper surface (17) is recorded. The workpiece (16) is moved into a further rotary position (c2) about the rotary axis (C), and again measured points in the measuring plane (E) on the upper surface (17) of the workpiece (16) are recorded. Based on these recorded measured points, the actual attitude (Li) of the workpiece (16) deviation from a specified target attitude (Ls) are determined. Adjustment parameters are determined, and an adjustment assembly (24) of the metrological apparatus (15) is activated as a function of the calculated adjustment parameters to adjust the workpiece (16).

The spatial structure of an optical element is determined. The optical element has a first optically active surface and a second optically active surface. The optical element is arranged in a holding device. The position of a point (P) on the first optically active surface and the position of a point (P′) on the second optically active surface are referenced in a coordinate system fixed to the holding device. The topography of the first optically active surface is determined in a coordinate system referenced to the holding device by the position of point (P) and the spatial structure of the optical element is calculated from the topography of the first optically active surface and from a data set as to the topography of the second optically active surface. The data set is referenced to the fixed coordinate system of the holding device by the position of point (P′).

Generating a composite image of a non-flat surface includes: acquiring, using a microscope, multiple images of different areas of the non-flat surface, where each image includes a region of overlap with at least one adjacent image, the microscope having sufficient resolution to image in three dimensions a microstructure on the non-flat surface having a lateral dimension of 10 microns or less and a height of 10 nm or less; determining, for each of the images, a set of rigid body parameters relating a position and orientation of the test object in the image to a common coordinate system, where the set of rigid body parameters is determined by fitting the resolved microstructure in the overlap region in the image with the corresponding microstructure in the overlap region of the adjacent image; and combining the images based on the sets of rigid body parameters to generate a composite image.

A slit m is projected onto an object surface in which reference point X.sub.1 is in a horizontal axis x closest to in focus point P. One image of a field of view area F is acquired after reflection of light comprising said reference point X.sub.1. Position Z.sub.1 of the object in a vertical axis z is determined. Images of respective field of view areas F are acquired after reflection of light having reference points X.sub.2, X.sub.3 . . . X.sub.n by simultaneously moving the object along axis z to maintain reference points X.sub.2, X.sub.3 . . . X.sub.n closest to in focus point P. Positions Z.sub.2, Z.sub.3 . . . Z.sub.n in which images were acquired are determined. The in focus point P along horizontal axis x is determined for each image. A correction differential Δ.sub.1, Δ.sub.2 . . . Δ.sub.n between in focus point P and reference points X.sub.1, X.sub.2 . . . X.sub.n is calculated.