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 method and a device for measuring the topography and/or the gradients and/or the curvature of an optically active surface of an object are disclosed. The device allows the object to be arranged in a receiving region with a contact surface for contact with the object. Inside the device, there is a plurality of point light sources that provide light that is reflected at the surface to be measured of an object arranged in the receiving region. The device includes at least one camera with an objective assembly and an image sensor for detecting a brightness distribution which is produced on a light sensor by the light of the point light sources reflected at the surface to be measured.

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 lens-measuring machine includes: a table rotatable around a rotation axis; a lens holder that holds a workpiece in a form of a lens, the lens holder being placed on the table so that an optical axis of the lens becomes orthogonal to the rotation axis; a contact tip that contacts a measurement surface of the lens; an angle sensor for detecting a rotary angle of the table; a displacement detector for detecting a displacement of the contact tip; and a controller for calculating coordinates information of the measurement surface of the lens in a form of polar coordinates, whose origin is at the rotation axis, based on displacement of the contact tip for every predetermined rotary angle of the table, the controller converting the calculated polar coordinates into Cartesian coordinates.

A computer-implemented system and method for examining the integrity of a structure having a visually repetitive pattern such as a fence, includes an imaging system having a light source and an optical element to produce a narrow substantially vertical light beam, and a photodetector to receive reflected light. The light beam is directed at the structure while moving laterally, producing a planar image of the structure which is continually refreshed. The system processes the images and identifies an anomalous feature from an anomaly in the repetitive pattern.

A multi-wavelength wavefront system and method for measuring diffractive lenses. A system may include one or more light sources configured to emit a plurality of wavelengths of light for diffraction by a diffractive lens. A light sensor may be configured to receive the light that is diffracted by the diffractive intraocular lens. A processor may be configured to determine one or more of the plurality of wavelengths that have a peak diffraction efficiency for the diffractive intraocular lens based on the light received by the light sensor.

A wavefront based characterization of surfaces based on reflections. An intraocular lens surface measurement system includes a light source configured to emit light that is reflected off an optical surface of an intraocular lens. A wavefront sensor is configured to receive the light that is reflected off the optical surface of the intraocular lens. A processor is configured to determine one or more characteristics of the optical surface of the intraocular lens based on a wavefront of the reflected light that is received by the wavefront sensor.

An eye implant with an optical implant region for correcting an imaging error of the eye. Biometrically determined data of optically effective components located in front of the retina of the eye is obtained through wave front measurement. The optical implant region is adjusted, based on the biometrically determined data, for a monofocal vision with a visual acuity of at least 0.7 (70%) within a field of focus depth of at least 2 diopters.

A measurement apparatus includes a filter changing a light amount of an irradiation light, a lens irradiating a surface of a material with the irradiation light, a stage changing a focus position of the irradiation light in a depth direction of the material, an interfering light extractor causing the irradiation light to interfere with reflected light from the material, a detector detecting an intensity of interfering light obtained by interference between the irradiation light and the reflected light, and a controller calculating a height of the surface of the material based on the detected intensity of interfering light while changing a relative focus position of the irradiation light with respect to the material at a given measurement point of the surface of the material. The controller controls the filter or light source based on the detected intensity of interfering light to change the light amount of the irradiation light.

A light source capable of spectral modulation is modulated conventionally to produce a correlogram at the test surface position of an SCI interferometer. The mean wavelength of the light source is changed to obtain multiple corresponding phase-shifted correlograms that can be processed by applying conventional multiple-wavelength interferometric analysis to determine physical attributes of the test surface. One simple way to achieve this result is by splitting the light beam produced by the source into at least three simultaneous beams passed through filters with corresponding different mean-wavelength transmission bands. Because the correlograms are produced simultaneously, they can be used to practice instantaneous phase-shifting interferometry using conventional analysis algorithms.