99 results about "Astigmatism correction" patented technology

A sequential wavefront sensor comprises a light beam scanning module, a sub-wavefront focusing lens, a detector with more than one photosensitive area and a processor for calculating the sequentially obtained centroids of a number focused light spots from the sub-wavefronts to determine the aberration of the input wavefront. A sequential wavefront sensing method comprises the steps of; sequentially projecting a number of sub-wavefronts onto a sub-wavefront focusing lens and a detector with more than one photosensitive areas, calculating the centroid of the focused light spot from each sub-wavefront, and processing the centroid information to determine the aberration of the wavefront. In particular, a method for auto-focusing and/or auto-astigmatism-correction comprises the steps of sequentially projecting a number of sub-wavefronts around an annular ring of a wavefront to a sub-wavefront focusing lens and a detector, calculating the centroid of focused light spot from each sub-wavefront to figure out the centroid trace and hence the defocus and/or astigmatism, adjusting the focus and/or astigmatism of the optical imaging system before the wavefront sensor so that the measured defocus and/or astigmatism is minimized.

Provided is a laser scanning observation device including: a window unit provided in a partial area of a casing and configured to be in contact with or close to an observation target; an objective lens configured to collect laser light on the observation target through the window unit; an optical path changing element configured to change a direction of travel of the laser light guided within the casing toward the window unit; an astigmatism correction element provided in a front stage of the window unit and configured to correct astigmatism occurring upon the collection of the laser light on the observation target; and a rotation mechanism configured to allow at least the optical path changing element to rotate about a rotation axis perpendicular to a direction of incidence of the laser light on the window unit to scan the observation target with the laser light.

A molded contact lens comprising a stiffer optic zone relative to the peripheral zone of the contact lens provides an optical element for correcting astigmatism without the need for or substantially minimizing the need for the correction of rotational misalignment. The higher elastic modulus optic zone vaults over the cornea thereby allowing a tear lens to form. The tear lens follows or assumes the shape of the back surface of the contact lens. The combination of the tear lens and the optical zone provide an optical element for correction of refractive error.

One embodiment is a method for finding, calculating and electronically marking a reference axis for astigmatism correction/neutralization of a patient eye during a refractive surgery.

The reference axis for astigmatism correction/neutralization can be determined intra-operatively based on one or more eye property measurements together with simultaneous recording a live eye image. The determined reference axis of astigmatism correction/neutralization can be updated and registered with one or more land mark(s) of the recorded eye image(s); and overlaid onto a live image of the eye. Another embodiment is a method of calculating and displaying in real time compensated refractive errors of the eye under operation with refractive components due to temporary surgically induced factors removed and refractive components due to surgeon-induced factors added.

In an apparatus for obtaining an image by irradiating a charged particle beam on a specimen, a condition of the beam conditioned differently from vertical incidence as in the case of the beam being tilted is required to be adjusted. To this end, the apparatus has a controller for automatically controlling a stigmator, an objective lens and a deflector such that astigmatism is corrected, focus is adjusted and view filed shift is corrected. The controller has a selector for inhibiting at least one of the astigmatism correction, focus adjustment and FOV shift correction from being executed.

In an electron microscope, focus correction is carried out automatically, an astigmatic difference amount is displayed and astigmatism correction is executed quantitatively. Enlarged specimen images obtained by irradiating an electron beam on a specimen while changing excitation currents of an objective lens and of a stigmator coil are picked up by a capturing unit comprised of an optical lens and a capturing device and image sharpness coefficients are calculated by means of an arithmetic logic unit. A suitable astigmatism correction direction is chosen on the basis of an angular component value of the obtained image sharpness coefficients and then, a correction excitation current is supplied to a stigmator coil to correct astigmatism and a correction excitation current is supplied to an objective lens coil to perform focus correction.

A method of selecting a toric lens by taking into consideration the magnitude and orientation of the posterior cornea and/or the location of the incision axis is described. The magnitude and orientation of the posterior cornea can be calculated as a function of the measured pre-operative orientation of the steep meridian of the anterior cornea.

The invention relates to a spectrometer using a cylindrical lens for astigmatism correction. The spectrometer comprises an incidence slit, a cylindrical surface lens, a concave surface alignment reflector, a plane grating, a concave focusing mirror and a line array CCD detector, wherein incidence lights pass through the incidence slit and the cylindrical surface lens in sequence, and then are irradiated on the concave surface alignment reflector; light beams of the concave surface alignment reflector are parallelly irradiated on the plane grating; and the light beams split by the plane grating are irradiated on the focusing mirror and focused on the linear array CCD detector. The spectrometer uses the cylindrical surface lens for focusing and correcting spectrometer astigmatism and increases the measuring sensitivity of the spectrometer in the situation of non obvious increased cost compared with the light path adopted at the present. The spectrometer is characterized by small volume and low cost.

An intraocular lens is provided that includes a refractive element and a mask. The refractive element has a first power in a first meridian and a second power greater than the first power in a second meridian. A magnitude of the first and second powers and a location of the first and second meridians are configured to correct astigmatism in a human eye. The mask is configured to block a substantial portion of light from passing through an annular region thereof and to permit a substantial portion of light to pass through a central aperture thereof to enhance an astigmatism correction rotational misplacement range and depth of focus.

There are provided an electron microscope capable of carrying out focusing and astigmatism correction without depending on characteristics of a sample, and a method for controlling its focus position.

The electron microscope according to the present invention comprises: an electron optical system (2); a focus control part (3); an image detecting part (4); a first operating part (11) for mutually dividing first and second transformed images (9) and (10), which are obtained by carrying out the fast Fourier transform of first and second images (7) and (8) detected at two focus positions of a first focus position (f1) and a second focus position (f2) shifted from the first focus position by a known focus shifted quantity Δf, to obtain a measured divided quantity Rexp; divided quantity data (12) previously prepared and stored as a function of focus positions and spatial frequencies as a set of theoretical divided quantities, the theoretical divided quantities being obtained by substituting the two focus positions shifted by the focus shifted quantity Δf for an image transfer function (r,f) to obtain first and second transfer function values K(r;f) and (r;f+Δf) to mutually divide the first and second transfer function values K(r;f1) and (r;f+Δf) on a spatial frequency plane; and a second operating part (13) for making a reference to the divided quantity data (12) to derive a theoretical divided quantity K(r;f0) correlating to the measured divided quantity Rexp, and for deriving a focus position f0 corresponding to the derived theoretical divided quantity K(r;f0)/K(r;f0+Δf) as a first focus position f1.

The present invention relates to novel ophthalmic lens elements (402, 404) and eyewear (400) having wide field of view, low distortion, improved astigmatism correction where required and enhanced eye protection properties. Series of lens elements have steeply curved spherical reference surfaces. The edged lenses of the series have approximately consistent aperture size, shape and hollow depth across a range of common prescriptions. Novel sunglasses, laser protection eyewear, and lens edgings, coatings, and frames are included in the invention.

The present invention is to provide an improved aberration correction device formed by inserting an electro-optic panel such as a liquid crystal panel in an image-formation optical system to correct aberrations in the image-formation optical system, characterized in that such a correction device is capable of correcting three or more kinds of aberrations using only one electro-optic panel. Divided areas concerning coma aberration correction and divided areas concerning astigmatism correction are formed in one of the transparent electrodes of the electro-optic panel, while the rest of divided areas concerning coma aberration correction and divided areas concerning spherical aberration correction are formed in the other of the transparent electrodes. In this way, it is possible to form divided areas divided into electrode patterns suitable for correcting various aberrations, simplify as much as possible the electrode structure of the transparent electrodes consisting of the divided areas, thereby simplifying a control of voltages to be applied to the divided areas.

According to the invention, techniques for automatically adjusting for astigmatism in a charged particle beam apparatus. Embodiments according to the present invention can provide a charged particle beam apparatus and an automatic astigmatism adjustment methods capable of automatically correcting astigmatism and a focal point in a relatively short period of time by finding a plurality of astigmatism correction quantities and a focal point correction quantity in a single operation from a relatively small number of 2 dimensional images. Specific embodiments can perform such automatic focusing while minimizing damages inflicted on subject samples. Embodiments include, among others, a charged particle optical system for carrying out an inspection, a measurement and a fabrication with a relatively high degree of accuracy by using a charged particle beam.

An optical probe comprises a light-guiding component, an optical component, a light-reflecting component that is configured to receive light from the optical component and direct the light along a path, and a correction component. The correction component lies in the path, the correction component has an optical power, and the correction component has a center of curvature that substantially coincides with an optical axis of the optical component.