578results about "Geometric properties/aberration measurement" patented technology

Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts. A spherical or partial spherical wavefront is generated from a known origin along an optical axis. The test optic is aligned with respect the optical axis and selectively moved along it relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at radial positions where the spherical wavefront and the aspheric surface intersect at points of common tangency. An axial distance, ν, and optical path length, p, are interferometrically measured as the test optic is axially scanned by the spherical wavefront where ν is the distance by which the test optic is moved with respect to the origin and p is the optical path length difference between the apex of an aspherical surface associated with the test optic and the apex of the circles of curvature that intersect the aspherical surface at the common points of tangency. Coordinates of the aspherical surface are calculated wherever the circles of curvature have intersected the aspherical surface and in correspondence with the interferometrically measured distances, ν and p. Afterwards, the shape of the aspheric surface is calculated. Where the test optic comprises a refracting optic a known spherical reflecting surface is provided upstream of the refracting optic for movement along the optical axis and a known wavefront is made to transit the refracting optic, reflects from the known spherical surface, again transits the refracting optic traveling towards the known origin after which the interferogram is formed. In another aspect of the invention, a spherical reference surface is provided to form a Fizeau that is used to generate phase information for measuring spheres, mild aspheres, and multiple mild aspheres.

Exposures of a photosensitive material through an array of blazed gratings illuminate a lens asymmetrically to detect effects of a plurality of azimuthal aberrations including coma, astigmatism, and three-leaf and four-leaf clover aberrations. A plurality of such exposures of the array of blazed gratings at slightly differing focus allows detection of focus shift due to any aberrations present in the lens. Upon development of the plurality of exposures, contrast of each area is measured, for example, by reflection or scattering from the relief in the developed photosensitive material and the aberrations thus detected can be simulated by effective summation of individual aberration effects.

Interferometric scanning method(s) and apparatus for measuring rotationally and non-rotationally symmetric test optics either having aspherical surfaces or that produce aspherical wavefronts. A spherical or partial spherical wavefront is generated from a known location along a scanning axis though the use of a decollimator carrying a spherical reference surface. The test optic is aligned with respect to the scanning axis and selectively moved along it relative to the known origin so that the spherical wavefront intersects the test optic at the apex of the aspherical surface and at radial zones where the spherical wavefront and the aspheric surface possess common tangents. The test surface is imaged onto a space resolving detector to form interferograms containing phase information about the differences in optical path length between the spherical reference surface and the test surface while the axial distance, v, by which said test optic moves relative to said spherical reference surface is interferometrically measured. Based on an analysis of the phase information contained in the interferograms and the axial distance, v, the deviation in the shape of the aspheric surface from its design in a direction normal to the aspheric surface is determined. In scanning, two cameras having different magnification are preferably used simultaneously with the one of higher magnification observing near the part axis where high fringe densities occur while that of lower magnification observes the full part surface. Special procedures are described for alternately improving accuracy near the axis.

Interferometric apparatus and methodology for precisely measuring the shape of rotationally and non-rotationally symmetric optical surfaces comprising an illumination source with two wavelengths, a transmission flat with a reference surface, a basic optical system for producing a wavefront of predetermined shape, a compensation component having an aspheric wavefront shaping surface and an aspheric reference surface. The aspheric shaping surface modifies the predetermined wavefront so that it impinges on the aspheric reference surface with a shape substantially that same as that of aspheric reference surface. For a given aspheric reference surface, the radius or curvature and spacing of the aspheric shaping surface are optimized so that its aspheric departure is no larger than that of the aspheric reference surface. Precise alignment in six degrees of freedom is provided via feedback control.

A process of measuring a shape while changing the relative posture of an microscopic interferometer to a sample lens which is rotated about a rotation axis is divided into a process of measuring a top surface in a state where the sample lens is supported from a back surface and a process of measuring a back surface in a state where the sample lens is supported from the top surface. By combining first shape information of a flange side surface acquired by the process of measuring the top surface and second shape information of the flange side surface acquired by the process of measuring the back surface, the relative positional relation between the sample top surface and the sample back surface is calculated.

A method of processing an optical element comprises testing the optical surface of the optical element using an interferometer optics for generating a beam of measuring light; wherein the interferometer optics has a plurality of optical elements which are configured and arranged such that the measuring light is substantially orthogonally incident on a reflecting surface, at each location thereof; and wherein the method further comprises: measuring at least one property of the interferometer optics, disposing the optical surface of the optical element at a measuring position relative to the interferometer optics within the beam of measuring light, and performing at least one interferometric measurement; determining deviations of the optical surface of the first optical element from a target shape thereof, based on the interferometric measurement and the at least one measured property of the interferometer optics.

Optical element having an optical surface, which optical surface is adapted to a non-spherical target shape, such that a long wave variation of the actual shape of the optical surface with respect to the target shape is limited to a maximum value of 0.2 nm, wherein the long wave variation includes only oscillations having a spatial wavelength equal to or larger than a minimum spatial wavelength of 10 mm.

A microinterferometer applies low coherent measurement light, which travels along an optical axis in a converging manner, to a front surface of a flange. A part of the measurement light is reflected inside an interferometric optical system, and becomes reference light. Apart of the measurement light passed through the interferometric optical system is reflected from the front surface of the flange, and is incident again upon the interferometric optical system. By combining the reflected light with the reference light, interference light is obtained. While a sample rotating stage rotates a sample lens through 360 degrees, a first imaging camera having one-dimensional image sensor captures 3600 images of the interference light, i.e., the image of the interference light is captured every time the sample lens is rotated by 0.1 degrees. Based on the images of interference fringes, the shape of the front surface of the flange is analyzed.

An apparatus includes a measurement unit and a calculation unit, wherein the calculation unit expresses a measurement error of each measurement as a polynomial including a term that has a coefficient whose value is dependent on setting of the measurement area and a term that has a coefficient whose value is not dependent on the setting of the measurement area, obtains a matrix equation with respect to the coefficients of the polynomial by applying a least-squares method to each of the measurement data items for the overlapping region, assigns data about the terms of the polynomial and each of the measurement data items for the overlapping region to the matrix equation, calculates the coefficients of the polynomial from a singular value decomposition of the matrix equation to which the data has been assigned, and corrects each of the measurement data items for the measurement areas by using the coefficients.

A variable near-null compensator for measuring aspheric surfaces by subaperture stitching includes a pair of counter-rotating CGH phase plates, each of the phase plates having a phase function including two terms Z5 and Z7 of Zernike polynomials. The phase plates are mounted on a pair of precision rotary center-through tables, wherein rotational axes of the pair of precision rotary center-through tables coincide with the optical axes of the phase plates. A figure metrology apparatus includes a wavefront interferometer, the test mirror mount, the near-null compensator and the mechanical adjustment components therefor. The optical axis of the near-null compensator coincides with the optical axis of the interferometer. A method for measuring aspheric surfaces by subaperture stitching includes the steps of mounting the test mirror, measuring the subapertures with the figure metrology apparatus, and finally processing the data by stitching.

A lens shape measurement device, includes: a rotation unit that rotates a lens supported by a stage; a laser displacement meter; a first moving unit that moves the laser displacement meter in a X-direction; a second moving unit that moves the lens in a Y-direction; and a drive controller that controls a drive of the rotation unit, the first moving unit, and the second moving unit in a mirror reflection state in which an incidence angle of the laser beams incident on a measurement target from the laser displacement meter, and a reflection angle of the laser beams reflected by the measurement target are equal to each other with a normal line of the lens passing through the measurement target set as a reference, for each of a plurality of measurement targets set on an edge of the lens in a rotating direction of the lens.