Embodiments of systems and methods for measuring a surface topography of a semiconductor chip are disclosed. In an example, a method for measuring a surface topography of a semiconductor chip is disclosed. A plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of the semiconductor chip are received by at least one processor. The plurality of interference signals are transformed by the at least one processor into a plurality of spectrum signals each corresponding to the respective one of the positions on the surface of the semiconductor chip. The spectrum signals are classified by the at least one processor into a plurality of categories using a model. Each of the categories corresponds to a region having a same material on the surface of the semiconductor chip. A surface height offset between a surface baseline and at least one of the categories is determined by the at least one processor based, at least in part, on a calibration signal associated with the region corresponding to the at least one of the categories. The surface topography of the semiconductor chip is characterized by the at least one processor based, at least in part, on the surface height offset and the interference signals.

The present invention provides a method of measuring a shape of a surface of an object, the method including obtaining shape data for each of a plurality of regions on the surface by a surface measurement for each of the plurality of regions, each of the plurality of regions having a region overlapping another of the plurality of regions, obtaining an error of the surface measurements so as to minimize a difference in shape with respect to the overlapping regions based on the obtained shape data, and obtaining the shape of the surface based on the obtained shape data and the obtained error, wherein the shape data is obtained so as not to include a component having a spatial frequency higher than a threshold determined based on a required precision.

Embodiments of systems for classifying interference signals are disclosed. In an example, a system for classifying interference signals includes an interferometer including a light source and a detector, and at least one processor. The interferometer is configured to provide a plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of a semiconductor chip. A spectrum of the light source is greater than a spectrum of white light. The at least one processor is configured to classify the interference signals into a plurality of categories using a model. Each of the categories corresponds to a region having a same material on the surface of the semiconductor chip.

An optical frequency domain reflectometer according to the invention includes: a swept light source that outputs wavelength-swept light; an auxiliary interferometer that has a the auxiliary interference signal generating delay fiber and outputs an auxiliary interference signal from the wavelength-swept light; a measurement interferometer that has a measurement target optical fiber and outputs a measurement interference signal from the wavelength-swept light; a plurality of linearization units that have different delay times, compensate non-linearity in a wavelength sweep of the swept light source for the measurement interference signal, using the auxiliary interference signal, and output compensated signals as output signals; and a weighted addition and Fourier transform unit that outputs a frequency domain signal as a result of addition and Fourier transformation of weighted signals which are multiplying the output signals from the plurality of linearization units by different weights.

An optical coherence tomography (OCT) image composed of a plurality of A-scans of a structure is analysed by defining, for each A-scan, a set of neighbouring A-scans surrounding the A-slices scan. Following an optional de-noising step, the neighbouring A-scans are aligned in the imaging direction, then a matrix X is formed from the aligned A-scans, and matrix completion is performed to obtain a reduced speckle noise image.

Exemplary apparatus and method are provided. In particular, an electromagnetic radiation can be emitted with, e.g. a light source arrangement. For example, the light source arrangement can include a cavity and a filter, and a spectrum of the electromagnetic radiation can be controlled, e.g., with such cavity and filter, to have a mean frequency that changes (i) at an absolute rate that is greater than about 100 terahertz per millisecond, and (ii) over a range that is greater than about 10 terahertz. Additionally or alternatively, the light source arrangement can include a frequency shifting device which can shift the mean frequency of the electromagnetic radiation.

An OCT device includes a light source that outputs light including a plurality of wavelengths; a division unit that divides light output from the light source into reference light and measurement light; a measurement arm that forms a light path of the measurement light with which a measurement target is irradiated and reflected light from the measurement target, which is generated by the measurement light; a reference arm that forms a light path of the reference light; and a measurement unit that measures the measurement target based on interference light between the reflected light and the reference light. At least one of the measurement arm and the reference arm includes a dispersion unit that disperses light into lights of each wavelength and a dispersed light path portion that forms light paths of dispersed lights, the light paths having a light path length different for each wavelength.

A digitizer and processor device for a swept-source optical coherence tomography (SS-OCT) imaging system, comprising: an input configured to receive an OCT signal; a control input configured to receive a k-clock signal; a combiner unit (130) receiving the OCT signal and the k-clock signal configured to output a composite signal; a digitizing unit (60) arranged to convert the composite signal into a digital composite signal (69); a data processing unit (70) arranged to determine a profile of optical density in a sample that generated the OCT signal based on the digital composite signal (69).

Interferometric measurement signals are detected by a single optical interferometric interrogator for a length of a sensing light guide and an interferometric measurement data set corresponding to the interferometric measurement signals is generated. The interferometric measurement data set is transformed into a spectral domain to produce a transformed interferometric measurement data set. The transformed interferometric measurement data set is compared to a baseline interferometric data set to identify a time-varying signal corresponding to a time-varying disturbance. The baseline interferometric data set is representative of the sensing light guide not being subjected to the time-varying disturbance. A compensating signal is determined from the time-varying signal and used to compensate at least a portion of the interferometric measurement data set for the time-varying disturbance as part of producing a measurement of the parameter.

An ophthalmic apparatus may include: a wavelength sweeping light source; a reference optical system; a calibration optical system; a light receiving element configured to receive calibration interference light which is a combination of calibration light and reference light; and a signal processor configured to sample a calibration interference signal outputted from the light receiving element when it receives the calibration interference light. The signal processor may sample the calibration interference light in at least first and second frequency bands, which are different and used for measuring a specific region of a subject eye. The ophthalmic apparatus calculates a difference between first and second waveforms, the first waveform being a waveform of the calibration interference signal that is sampled in the first frequency band and Fourier transformed, the second waveform being a waveform of the calibration interference signal that is sampled in the second frequency band and Fourier transformed.