A tomographic imaging system includes a light source, a light irradiation unit that irradiates light to a transparent material composite thin film sample and a reference mirror and acquires an interference signal between light reflected and scattered from the sample and light reflected from the reference mirror, a light measuring unit that measures the interference signal acquired by the light irradiation unit, a light transmission unit that transmits the light output from the light source to the light irradiation unit and transmits the interference signal of the light transmitted from the light irradiation unit to the light measuring unit; and a signal processing apparatus that converts the interference signal of the sample, outputs the converted interference signal as a tomographic image, and monitors the interference signal acquired by the light irradiation unit to modulate intensity and a polarization state of the light input to the light irradiation unit.

A method for measuring geometric errors of a numerical control turntable based on a four-station laser tracer system includes: establishing a self-calibration coordinate system and calibrating positions of tracking interferometers; respectively placing each of target lenses at three non-coplanar points that are above the numerical control turntable and keep certain distances from the numerical control turntable, controlling the numerical control turntable to rotate at a certain angular interval θ.sub.j, and based on positions of the tracking interferometers being known after calibration, solving coordinates of each of measurement points in the self-calibration coordinate system using a non-linear least square method; establishing a turntable coordinate system; perform a conversion between the turntable coordinate system and the self-calibration coordinate system; separating six geometric errors of the numerical control turntable using spatial position errors of the three points at a same position and using the linear least squares method.

Method for simultaneously compensating pupil coordinate distortion and shear amount change in a process of wavefront reconstruction in grating transverse shear interference. Where a wavefront is diffracted by a grating, the shapes and light paths of the diffracted wavefronts of all the orders are different, so that on one hand, a coordinate system detected by a detector plane is distorted relative to a pupil coordinate system, and on the other hand, a shear amount changes along with a coordinate position.

An analysis apparatus includes an acquisition part that acquires a plurality of interference images of the object to be measured from the interference measurement apparatus, a calculation part that calculates a sine wave component and a cosine wave component of an interference signal for each pixel in the plurality of interference images, respectively, an error detection part that detects an error between a first Lissajous figure constructed on the basis of the sine wave component and the cosine wave component for each pixel and an ideal second Lissajous figure, a correction part that corrects the sine wave component and the cosine wave component for each pixel on the basis of the error, and a geometry calculation part that calculates surface geometry of the object to be measured on the basis of the corrected sine wave component and cosine wave component.

A method and apparatus for measuring a 3-D refractive index tensor are presented. The method for measuring a 3-D refractive index tensor according to an embodiment comprises the steps of: controlling incident light of a plane wave with respect to at least one angle and polarization; and measuring, in a polarization-dependent manner, the 2-D diffracted light of a specimen with respect to the incident light incident at the at least one angle and polarization, wherein the birefringence value and the 3-D structure of an alignment direction of molecules in the specimen having birefringence may be measured.

A method and apparatus for measuring a 3-D refractive index tensor are presented. The method for measuring a 3-D refractive index tensor according to an embodiment comprises the steps of: controlling incident light of a plane wave with respect to at least one angle and polarization; and measuring, in a polarization-dependent manner, the 2-D diffracted light of a specimen with respect to the incident light incident at the at least one angle and polarization, wherein the birefringence value and the 3-D structure of an alignment direction of molecules in the specimen having birefringence may be measured.

A method for reproducing a lumen curve to a given tolerance in at least one image in optical coherence tomography (OCT). Examples of applications include imaging, evaluating and diagnosing biological objects, such as, but not limited to, cardio applications, and being obtained via one or more optical instruments, such as, but not limited to, catheters. The method may include obtaining a set of original points of the curve that correspond to measurements from an optical imaging device. Filtering the set of original points using at least one criteria to obtain a subset of original points. The method may also include determining if the subset of original points is less than a predetermined threshold and adjusting the at least one criteria to increase an amount of original points included in the subset of original points when it is determined that the subset of original points is less than the predetermined threshold.

Examples disclosed herein are directed to a method and apparatus for determining a position of a ring within a process kit. In one example, a sensor assembly for a substrate processing chamber is provided. The sensor assembly includes a housing having a top surface, a bottom surface opposite the top surface, and a plurality of sidewalls connecting the top surface to the bottom surface. The housing also has a recess in the top surface, the recess forming an interior volume within the housing. The sensory assembly includes a bias member, and a contact member disposed on the bias member. The bias member and contact member are disposed within the recess. A sensor is configured to detect a displacement of the contact member. The displacement of the contact member corresponds to a relative position of an edge ring.

To optimize an imaging range in a depth direction in terms of a relationship with a resolution, an OCT apparatus includes a signal processor that determines a reflected light intensity distribution of an imaging object on the basis of a spectrum of a detected interference light. The signal processor performs spectrum conversion, having a conversion characteristic with which a light source spectrum is converted to a Gaussian distribution curve, on the spectrum of the interference light, and determines the reflected light intensity distribution by Fourier-transforming a spectrum resulting from the spectrum conversion. In the conversion characteristic, the light source spectrum and the Gaussian distribution curve have center wavelengths differing from each other.

In an aspect, a method for imaging a target comprises steps of: performing optical coherence tomography (OCT) scanning on the target with one or more beams of source light, the one or more beams of source light comprising a plurality of wavelengths; wherein performing OCT scanning comprises: providing the source light to a reference optical path and to a sample optical path, wherein providing the source light to a sample optical path comprises illuminating the target with the source light; and recording interference data corresponding to an interaction of a light from the reference optical path and a light from the sample optical path; processing the interference data; and identifying blood or one or more blood-features in the target based on an optical attenuation of light in or associated with the sample optical path by the blood or the one or more blood-features.