A shape measuring apparatus of the present invention measures a variation in a thickness of an object to be measured WA based on an A surface reference interference light and an A surface measuring interference light obtained by performing optical heterodyne interference on a first A surface measuring light and a second A surface measuring light and a B surface reference interference light and a B surface measuring interference light obtained by performing the optical heterodyne interference on a first B surface measuring light and a second B surface measuring light. When the optical heterodyne interference is performed, the shape measuring apparatus makes the first A surface measuring light and the second B surface measuring light equal in frequency and makes the first B surface measuring light and the second A surface measuring light equal in frequency.

The present subject matter at-least provides an apparatus for characterization of a slab of a material. The apparatus comprises a plurality of frequency-domain optical-coherence tomography (FD-OCT) probes configured for irradiating the slab of material at at-least one location, and detecting radiation reflected from the slab of material or transmitted there-through. Further, a centralized actuation-mechanism is connected to the plurality of OCT probes for simultaneously actuating one or more elements in each of said OCT probes to at-least cause a synchronized detection of the radiation from the slab of material. A spectral-analysis module is provided for analyzing at least an interference pattern with respect to each of said OCT probes to thereby determine at least one of thickness and topography of the slab of the material.

A method is provided for determining the thickness of a retina. A single beam is used to illuminate the retina of a patient. Interference between reflections off different layers within the retina cause autocorrelation in the returned signal. A spectrometer produces a frequency spectrum of the beam reflected by the retina, and an FFT applied to the frequency spectrum produces a spatial domain signal (SDS). Autocorrelation within the reflected beam results in edges within the spatial domain signal, and the spatial coordinate of the SDS at which the power of the SDS drops precipitously indicates the distance between the nerve fiber layer (NFL) and the layers between the inner segment/outer segment (IS/OS) and the retinal pigment epithelium (RPE), the dominant scatterers. By analyzing autocorrelation, a single beam can be used. This avoids the problem of movement of the patient, arising in the use of a standard OCT interferometer, resulting in a simpler and less expensive technique of measuring retinal thickness.

A wear amount measuring apparatus includes a light source, a light transmission unit, a first and a second irradiation unit, a spectroscope and an analysis unit. The light transmission unit splits a low-coherence light from the light source into a first and a second low-coherence light. The first and the second irradiation units irradiate the first and the second low-coherence light to the component to receive reflected lights from the component. The light transmission unit transmits the reflected lights received by the first irradiation unit and the second irradiation unit to the spectroscope. The spectroscope configured to detect intensity distribution of the reflected lights from the first and the second irradiation unit. The analysis unit calculates a thickness difference between a thickness of the component at the first measuring point and that at the second measuring point by performing Fourier transform on the intensity distribution.

Inspecting a multilayer sample. In one example embodiment, a method may receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.

The present invention provides a measurement apparatus for measuring a shape of a test surface, comprising an optical system configured to irradiate a measurement point on the test surface and a reference surface with light, and cause test light and reference light reflected to interfere with each other, a detector configured to detect an optical path length difference between the test light and the reference light by using interfering light and a processor configured to determine a position of the measurement point based on a plurality of detection results by the detector, wherein a detection result includes an error which cyclically changes, and the plurality of detection results include n detection results obtained in n states in which optical path lengths of the test light are different from each other by 1/n (n2) of a cycle of the error.

The present invention may include acquiring a wafer shape value at a plurality of points of a wafer surface at a first and second process level, generating a wafer shape change value at each of the points, generating a set of slope of shape change values at each of the points, calculating a set of process tool correctables utilizing the generated set of slope of shape change values, generating a set of slope shape change residuals (SSCRs) by calculating a slope of shape change residual value at each of the points utilizing the set of process tool correctables, defining a plurality of metric analysis regions distributed across the surface, and then generating one or more residual slope shape change metrics for each metric analysis region based on one or more SSCRs within each metric analysis region.

Inspecting a multilayer sample may include receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.

The system includes a dual interferometer sub-system configured to measure flatness across a substrate. The system includes a mass sensor configured to measure the mass of the substrate. The system includes a controller communicatively coupled to the dual interferometer sub-system and the mass sensor. The controller includes one or more processors. The one or more processors are configured to execute a set of program instructions stored in memory, the set of program instructions configured to cause the one or more processors to determine a thickness distribution of at least one of the substrate or a film deposited on the substrate as a function of position across the substrate based on one or more flatness measurements from the dual interferometer sub-system and one or more mass measurements from the mass sensor.

A measurement apparatus includes a measurement optical system configured to make first light emitted from a chart enter a tested optical system, an image sensor configured to receive the first light, an adjusting unit configured to adjust relative positions of the measurement optical system and the tested optical system, an interferometer configured to acquire an interference signal by causing interference between reference light and test light, a correction unit configured to correct a condensing position deviation between the first light and the test light, and an acquiring unit configured to acquire an optical path length from the first point to the plurality of test surfaces based on the interference signal, and a distance between adjacent test surfaces among the plurality of test surfaces based on the optical path length.