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 system for in-situ measurement of a curvature of a surface of a wafer comprises: a multiwavelength light source module, adapted to emit incident light comprising a plurality of wavelengths; an optical setup configured to combine the incident light into a single beam and to guide the single beam towards a surface of a wafer such that the single beam hits the surface at a single measuring spot on the surface; and a curvature determining unit, configured to determine a curvature of the surface of the wafer from reflected light corresponding to the single beam being reflected on the surface at the single measuring spot.

A system for in-situ measurement of a curvature of a surface of a wafer comprises: a multiwavelength light source module, adapted to emit incident light comprising a plurality of wavelengths; an optical setup configured to combine the incident light into a single beam and to guide the single beam towards a surface of a wafer such that the single beam hits the surface at a single measuring spot on the surface; and a curvature determining unit, configured to determine a curvature of the surface of the wafer from reflected light corresponding to the single beam being reflected on the surface at the single measuring spot.

A rocker arm grading system can comprise a grading tool. The grading tool can be used with a rocker arm to measure aspects of the rocker arm and determine a resulting valve lift. The grading tool can comprise a rocker arm jig comprising a pivot peg and a valve peg. A cam jig can comprise a cam arm. A cam pin can be mounted in the cam arm. A rocker arm can be removably mounted to the rocker arm jig. The rocker arm can comprise a radius on a bearing surface. A cam edge of the cam pin can press against the bearing surface. At least one measuring device comprising a wavelength emitting device paired with a wavelength detecting device can be configured to measure the radius of the bearing surface with respect to the pivot peg.

A rocker arm grading system can comprise a grading tool. The grading tool can be used with a rocker arm to measure aspects of the rocker arm and determine a resulting valve lift. The grading tool can comprise a rocker arm jig comprising a pivot peg and a valve peg. A cam jig can comprise a cam arm. A cam pin can be mounted in the cam arm. A rocker arm can be removably mounted to the rocker arm jig. The rocker arm can comprise a radius on a bearing surface. A cam edge of the cam pin can press against the bearing surface. At least one measuring device comprising a wavelength emitting device paired with a wavelength detecting device can be configured to measure the radius of the bearing surface with respect to the pivot peg.

The invention concerns a system for determining the topography of a diffusely reflecting curved surface, that comprises two telecentric projection branches that project fringe images of a Ronchi grating on the diffusely reflecting curved surface, and a viewing branch of which the optical system projects an image of the illuminated surface on its camera target, and comprises further a computer that receives the fringe images recorded by the camera target and calculates from these the topography of the anterior eye surfaces, in which system the projection sources are semiconductor diodes and the optical system of the viewing branch is two-sided telecentric.

The invention concerns a system for determining the topography of a diffusely reflecting curved surface, that comprises two telecentric projection branches that project fringe images of a Ronchi grating on the diffusely reflecting curved surface, and a viewing branch of which the optical system projects an image of the illuminated surface on its camera target, and comprises further a computer that receives the fringe images recorded by the camera target and calculates from these the topography of the anterior eye surfaces, in which system the projection sources are semiconductor diodes and the optical system of the viewing branch is two-sided telecentric.

A method, device and electronic apparatus for estimating physical parameters are disclosed. The method includes: reading a Newton's rings fringe pattern obtained by performing an interferometric measurement on a unit to be measured; obtaining the number and length of first-direction signals of the Newton's rings fringe pattern; performing, for each of the first-direction signals, a discrete chirp Fourier transform (DCFT) on the first-direction signal based on each first chirp rate parameter within a range of the length of first-direction signals, to obtain a first magnitude spectrum of an intensity distribution signal in a DCFT domain; determining a first chirp rate parameter and a first frequency parameter corresponding to a first magnitude peak value based on the first magnitude spectrum; and estimating the physical parameters involved in the interferometric measurement at least according to the first chirp rate parameter and first frequency parameter corresponding to the first magnitude peak value. In this way, the physical parameters involved in the interferometric measurement can be estimated with high accuracy and stably.

A method, device and electronic apparatus for estimating physical parameters are disclosed. The method includes: reading a Newton's rings fringe pattern obtained by performing an interferometric measurement on a unit to be measured; obtaining the number and length of first-direction signals of the Newton's rings fringe pattern; performing, for each of the first-direction signals, a discrete chirp Fourier transform (DCFT) on the first-direction signal based on each first chirp rate parameter within a range of the length of first-direction signals, to obtain a first magnitude spectrum of an intensity distribution signal in a DCFT domain; determining a first chirp rate parameter and a first frequency parameter corresponding to a first magnitude peak value based on the first magnitude spectrum; and estimating the physical parameters involved in the interferometric measurement at least according to the first chirp rate parameter and first frequency parameter corresponding to the first magnitude peak value. In this way, the physical parameters involved in the interferometric measurement can be estimated with high accuracy and stably.

A semiconductor structure and a method for managing semiconductor wafer stress are disclosed. The semiconductor structure includes a semiconductor wafer, a first stress layer disposed on and in contact with a backside of the semiconductor wafer, and a second stress layer on and in contact with the first stress layer. The first stress layer exerts a first stress on the semiconductor wafer and the second layer exerts a second stress on the semiconductor wafer that is opposite the first backside stress. The method includes forming a first stress layer on and in contact with a backside of a semiconductor wafer, and further forming a second stress layer on and in contact with the first stress layer. The first stress layer exerts a first stress on the semiconductor wafer and the second stress layer exerts a second stress on the semiconductor wafer that is opposite to the first stress.