355results about "Refractive power measurement" patented technology

Wavefront measuring systems and methods are disclosed which may be employed, for example, in detecting phase aberrations in a spectacle lens and in an eye. Various embodiments include disposing a modulation pattern in the path of a return beam from the spectacle lens or the eye, and imaging a diffraction pattern at a self-imaging plane relative to the modulation pattern with a detector. The diffraction pattern is analyzed and the results are used to produce a representation of the wavefront phase characteristics that describe aberrations in the lens or eye being measured. Illumination and processing techniques for improving the measurement results are dislcosed. Various embodiments comprise systems adaptable to both measure aberrations in lenses in spectacles as well as in a patient's eyes.

This invention provides a system and method for determining and controlling focal distance in a lens assembly of a vision system camera using an integral calibration assembly that provides the camera's image sensor with optical information that is relative to focal distance while enabling runtime images of a scene to be acquired along the image axis. The lens assembly includes a variable lens located along an optical axis that provides a variable focus setting. The calibration assembly generates a projected pattern of light that variably projects upon the camera sensor based upon the focus setting of the variable lens. That is, the appearance and / or position of the pattern varies based upon the focus setting of the variable lens. This enables a focus process to determine the current focal length of the lens assembly based upon predetermined calibration information stored in association with a vision system processor running the focus process.

A system for the inspection of the optical quality of a part, object or product having a portion comprising transparent material such as ophthalmologic lenses, protective eyewear, visors, eyewear shield and the like is provided. A liquid crystal display (LCD) screen emits variable patterns of light through the transparent part under inspection to a charged coupled device (CCD) camera that captures the image and transmits the image data to an image processing module. The processed image data are then transmitted to an analysis module which then generally measures the dimensions of the part, the transparency, the colour and the optical strength. The analysis module also advantageously detects and measures the presence of dots, stains, scratches, optical distortions, fingerprints, cloudiness and other optical artefacts and / or defects in the transparent material. Accordingly, the patterns emitted by the LCD screen are designed to measure the optical specifications and highlight potential optical defects.

Embodiments of the invention provide a method of determining one or more characteristics of a target object, comprising determining a first phase map for at least a region of a target object based on radiation directed toward the target object, determining one or more further phase maps for a sub-region of the region of the target object, determining a number of phase wraps for the sub-region based on a plurality of phase maps for the sub-region, and determining a characteristic of the region of the target object based on the number of phase wraps for sub-region and the first phase map. Embodiments of the invention also relate to a method of determining one or more characteristics of a target object, comprising determining a phase map for at least a region of a target object based on one or more diffraction patterns, determining a wavefront at a plane of the object based upon the phase map, and determining a refractive property of the object based on the wavefront.

The measuring method includes a step of causing reference light to enter an object placed in a first medium to measure a first transmitted wavefront, a step of causing the reference light to enter the object placed in a second medium to measure a second transmitted wavefront, a step of measuring first and second placement positions where the object is placed in the first and second media, and a calculating step of calculating an internal refractive index distribution of the object by using measurement results of the first and second transmitted wavefronts. The calculating step calculates the internal refractive index distribution from which a shape component of the object is removed by using the measurement results of the first and second transmitted wavefronts, and first and second reference transmitted wavefronts of a reference object to be placed at positions identical to the first and second placement positions.

An ophthalmic measurement and laser surgery system includes: a laser source; a corneal topography subsystem; an axis determining subsystem; a ranging subsystem comprising an Optical Coherence Tomographer (OCT); and a refractive index determining subsystem. All of the subsystems are under the operative control of a controller. The controller is configure to: operate the corneal topography subsystem to obtain corneal surface information; operate the axis determining subsystem to identify one or more ophthalmic axes of the eye; operate the OCT to sequentially scan the eye in a plurality of OCT scan patterns, the plurality of scan patterns configured to determine an axial length of the eye; operate the refractive index determining subsystem so to determine an index of refraction of one or more ophthalmic tissues, wherein at least one of the corneal surface information, ophthalmic axis information, and axial length is modified based on the determined index of refraction.

An apparatus for measuring the optical performance characteristics and dimensions of an optical element comprising a low coherence interferometer and a Shack-Hartmann wavefront sensor comprising a light source, a plurality of lenslets, and a sensor array is disclosed. The low coherence interferometer is configured to direct a measurement beam along a central axis of the optical element, and to measure the thickness of the center of the optical element. The light source of the Shack-Hartmann wavefront sensor is configured to emit a waveform directed parallel to and surrounding the measurement beam of the interferometer, through the plurality of lenslets, and to the sensor array. A method for measuring the optical performance characteristics and dimensions of a lens using the apparatus is also disclosed.

A method for the spatially resolved measurement of the birefringence distribution of a cylindrically symmetrical blank (2) made from an optical material transparent to at least one wavelength λB between 180 nm and 650 nm, in particular at 193 nm, including: irradiating the blank (2), arranged in a container (4) with an immersion fluid (5), at a jacket-side measurement position (MP) using a measuring light beam (9) which runs in a measuring direction (Y) preferably perpendicular to the axis of symmetry (S) of the blank (2), as well as varying the jacket-side measurement position (MP) by moving the measuring light beam (9) and the blank (2) relative to one another in two directions (X, Z) perpendicular to the measuring direction (Y) for the purpose of spatially resolved measurement of the non-axial birefringence distribution of the blank (2).

A system and method of characterizing through-focus visual performance of an IOL using metrics based on an area under the modulation transfer function for different spatial frequencies at different defocus positions of the IOL. Also disclosed is a system and method of characterizing through-focus visual performance of an IOL using a metric based on an area under a cross-correlation coefficient for an image of a target acquired by the IOL at different defocus positions of the IOL.

A method for calibrating a focus point for a camera lens may include capturing a reflection of a focus point measuring device that is affixed to the camera. The method may include evaluating a captured image of the reflection to measure a calibration amount for a focus point, and adjusting a focus point of a lens of the camera by the calibration amount. The focus point measuring device may include a substantially planar target surface defining a plane, and a ruled target surface inclined at substantially 45° to the substantially planar target and extending through the plane thereof, marked to indicate respective distances in front of and behind the plane. The device may further include a fixture for holding the substantially planar target surface and the ruled target surface in a defined orientation to the camera, enabling performance of the method.

A method includes a step of contactless optical measurement of the local value of at least one refringence optical characteristic of the lens over defined local zone around the measurement point of the lens, and at least one step of determining the axial position of the measurement point on one of the faces of the lens; the axial position of the measurement point obtained is compared with the local value of the optical characteristic of the lens at the measurement point as determined from the contactless optical measurement, in order to deduce therefrom at least one vertex optical power of the lens at the measurement point.

A refractive index distribution measurement method includes the steps of measuring a first transmission wavefront of a test object by introducing reference light to the test object immersed in a first medium having a first refractive index lower than that of the test object by 0.01 or more, measuring a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object by 0.01 or more and different from the first refractive index, and obtaining a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront.

An image processing apparatus is disclosed which can produce refractive index distribution data with high accuracy without limiting directions in which transmitted wavefronts are measured. The image processing apparatus has a simulating section which simulates a transmitted wavefront in each of the directions to produce a second transmitted wavefront image based on first refractive index distribution data, a comparing section which produces first information indicating the result of comparison between the second transmitted wavefront image and the first transmitted wavefront image, and a changing section which changes the first refractive index distribution data based on the first information to produce second refractive index distribution data. In the apparatus, the processing in the sections is repeated using the second refractive index distribution data as the first refractive index distribution data to produce the resulting second refractive index distribution data which is used as the output refractive index distribution data.

A method of measuring a polarization correlation parameter of a doubly-refractive material and an apparatus are disclosed. The method comprises the following steps of presetting a series of polarization crosstalk peaks with known distance periods along a length of the doubly-refractive material; introducing probe light and entering into the doubly-refractive material, and detecting the probe light from the doubly-refractive material; processing the detected probe light so as to determine a sensed polarization crosstalk peak position with the known distance period and a width; and using the acquired polarization crosstalk peak position with the known distance period and the width to extract one or more polarization correlation parameters of the doubly-refractive material.

A dioptric power distribution measuring device (1) measures the dioptric power distribution of a target lens. A computer (3) constructs a design lens spatial model in a virtual space, and calculates the dioptric power distribution of the design lens spatial model by performing simulation processing for incident / exit light for only the same point in the design lens spatial model as a measurement point on the target lens. The computer then compares the calculated dioptric power distribution with the dioptric power distribution of the target lens which is measured by the dioptric power distribution measuring device (1).

A device for automatically detecting characteristics of an ophthalmic lens includes a support receiving the lens, an illumination system and an analysis system. The optics of the illumination system define two alternate optical paths, one of which passes through a mask forming a Hartmann matrix.

A method includes the steps of measuring a first transmitted wavefront in a first medium having a first refractive index and a second transmitted wavefront in a second medium having a second refractive index different from the first refractive index, and obtaining a refractive index distribution projected value of the object in each orientation by removing a shape component of the object utilizing measurement results of the first transmitted wavefront and the second transmitted wavefront and each transmitted wavefront of a reference object that has the same shape as that of the object and a specific refractive index distribution and is located in one of the first medium and the second medium with the same orientation as that of the object, and calculating a three-dimensional refractive index distribution of the object based on a plurality of refractive index distribution projected values corresponding to the plurality of orientations.

The method measures first transmitted wavefronts and second transmitted wavefronts by respectively causing reference light to enter an object placed in plural placement states in a first medium and a second medium, calculates an aberration sensitivity with respect to changes of the placement state of the object, and calculates an alignment error of the object in each placement state by using the aberration sensitivity and the first and second transmitted wavefronts measured in each placement state. The method further calculates first and second reference transmitted wavefronts respectively acquirable when causing the reference light to enter the reference object placed in placement states including the alignment errors in the first medium and the second medium, and calculates a refractive index distribution of the object which a shape component thereof is removed, by using the first and second transmitted wavefronts and the first and second reference transmitted wavefronts.

A method includes measuring a transmitted wavefront of a test object by introducing reference light into the test object arranged in a medium having a refractive index different from a refractive index of the test object, and calculating a refractive index distribution of the test object by using a measurement result of the transmitted wavefront. The measuring step measures a first transmitted wavefront for a first wavelength and a second transmitted wavefront for a second wavelength different from the first wavelength. The calculating step calculates the refractive index distribution of the test object by removing a shape component of the test object utilizing measurement results of the first and the second transmitted wavefront, and a transmitted wavefront of a reference object arranged in the medium for each of the first and second wavelengths. The reference object has the same shape as the test object and a specific refractive index distribution.

A refractive-index measurement system includes a light source, a first beam splitter, a first reflective mirror, a second reflective mirror, a second beam splitter, a container, a first polarizer, and a second polarizer. The first beam splitter splits light emitted from the light source into first and second light beams. The first light beam and the second light beam are reflected by the first reflective mirror and the second reflective mirror, respectively, incident into the second light beam splitter. The container is positioned along an optical pathway of first light beam. The container accommodates a lens and is filled with a medium having a refractive index substantially the same as a theoretical refractive index of the lens. The first polarizer is positioned along the optical pathway of the first light beam. The second polarizer is positioned along an optical pathway of the second light beam.

By using two probe optical systems for measurement by disposing the probe optical systems with a test object sandwiched therebetween, an optical path length of light transmitted through the test object which is identified locally is calculated using an interference signal thereof. In addition, a geometrical thickness of the same part is calculated by measuring positions of the probe optical systems, whereby two calculated values are obtained. Based on the values and a calculated value for a reference object, a refractive index distribution of the test object is obtained.

The invention relates to a method and a device for measuring a refractive index of a broadband differential confocal infrared lens element and belongs to the technical field of precise optical measurement. The method disclosed by the invention comprises the following steps: generating a specified wavelength lighting point light source through a wavelength gating system by adopting a blackbody source; performing tomographic focus fixing on vertexes of the front and rear surfaces of a measured lens by utilizing a differential confocal light path, and measuring to obtain the optical thickness of the measured lens; and calculating to obtain the refractive index of the lens element by a ray tracing algorithm, thereby realizing high-precision non-contact measurement of the refractive index of the infrared lens element in a visible-to-infrared broadband range under any wavelength condition. According to the method disclosed by the invention, the measured lens does not need to be subjected to destructive sampling, nondestructive direct measurement of the refractive index of the infrared lens element in the visible-to-infrared range under any wavelength condition is realized for the first time, and the method has the advantages of being convenient in measurement process, high in measurement accuracy and high in environmental disturbance resistance and can provide a brand new effective technical approach for detecting the refractive index of the lens element.

This invention discloses a handheld apparatus for measuring surface power or radius of prescription ophthalmic spectacle lenses, optical lenses or molds blocked with or without chuck during Rx production, and after comparing measurement results with designed data, providing correction data to the processing machines via wireless connection for correction processing if needed. The handheld apparatus integrates an optical measurement head into a monolithic optical system.

A device for automatically measuring characteristics of an ophthalmic lens (L1), includes: a support (2) designed to receive such a lens; on one first side of the lens support, illuminating elements (208) including an optical system for producing a light beam directed towards the ophthalmic lens mounted on the support; and on a second side of the support, elements for analyzing (210) the image transmitted by the ophthalmic lens mounted on the support and illuminated by the illuminating elements (208); elements for splitting the light beam including a first mask (220) forming a Hartmann array and arranged on the first side of the lens support to be illuminated, upstream of the lens by the light beam.

A lens meter obtaining 0D-reference-coordinates of target-images not detected in a reference state and measuring even progressive lenses, has a lens rest, an optical system having an optical axis, a light source, measurement targets and a photo-sensor, a part calculating optical characteristics based on coordinates-change of target-images in a measurement state with the lens on the rest and axis from those in a reference state without the lens thereon, and an information memory. The part makes the memory store image-coordinates not detected in the reference state obtained during assembly / adjustment, and based on image-coordinates detected in the reference state after power application and before measurement and stored coordinates, obtains image-coordinates not detected in the reference state after power application and before measurement, and calculates characteristics based on coordinates-change of target-images detected in the measurement state from those detected in the reference state before measurement and obtained image-coordinates.

A lens meter for measuring refractive power distribution of a progressive power lens and displaying its distribution map, has a lens rest having an aperture, an optical system including an axis, a source projecting a light bundle along the axis, a plate having targets and a two-dimensional image sensor detecting images by the bundle passing through the lens, aperture and plate, a part calculating the distribution within a measurement region from detection results, a part detecting a lens-position in a two-dimensional direction orthogonal to the axis, a device guiding movement on the rest to shift the measurement region and obtaining the distribution within an analysis region including distance, progressive and near portions, a part storing the distribution in the measurement region in association with the detected position, a display part, and a part controlling to display the distribution map within the analysis region based on the stored distribution and position.

The measurement apparatus includes: a support arranged to receive a lens; lighting element including an optical system for generating a collimated light beam directed towards the lens under measurement installed on the support; detachment elements for detaching light rays from the light beam, for detaching a localized group of at least three non-coplanar light rays grouped together about a measurement axis in a measurement cylinder of section substantially smaller than the section of the lens under measurement; acquisition elements for identifying the deflections imparted by the lens on the detached light rays and for delivering a signal representative of the deflections; and an electronic and computer system programmed to deduce from said deflections the value of the refractive characteristic of the lens at the measurement point.

An automated lens inspection system that images the edge and surface of an ophthalmic lens transmits light through the ophthalmic lens to a camera to create a complete digital image of the lens edge or lens surface. The digitized image(s) is(are) analyzed to detect defects or abnormalities of the ophthalmic lens. Methods of inspecting ophthalmic lenses are also disclosed.