Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser, sintering, and welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.

A system (1) for generating a signal from a surface (22) having a speed V in a direction U, comprising: a light source (2) emitting a Gaussian beam of light along a first optical path (11); a sensor (3) able to evaluate the effects of the electromagnetic interference of the first beam; an optical splitter (4) located upstream of the sensor (3), generating, from the first beam of light, a second beam of light along a second optical path (12); a focusing lens (5, 6) located on the first and/or the second optical path (11, 12), focusing the beam of light at a distance f and defining an upstream optical path (11′, 12′), and a means (7) for routing the second beam, comprising a mirror redirecting the second path such that the lengths of the first (11′) and second (12′) paths are different.

Systems and methods for unwrapping a phase map are disclosed. Such systems and methods may include receiving a wrapped phase map associated with an interferometric measurement of a sample including patterned features; removing a tilt from the wrapped phase map; generating a background; detecting features in the wrapped phase, the features in the wrapped phase map corresponding to least some of the patterned features of the sample; replacing phases of the features with the background at corresponding locations in the wrapped phase map; unwrapping the modified wrapped phase map using a global phase-unwrapping; applying local phase-unwrapping to restore the phases of the features; and reapplying the tilt to generate an output unwrapped phase map.

The present disclosure provides an OCT imaging system having a variety of advantages. In particular, the OCT system of the present disclosure may provide a more intuitive interface, more efficient usage of controls, and a greater ability to view OCT imaging data.

A system and method for non-destructive optical coherence tomography (OCT) is provided. The system includes: an input interface for receiving OCT data including at least a C-scan; a processing unit executable to detect a feature on a surface or subsurface of the object, trained using a training set and configured to: separate the C-scan into A-scans; using a neural network, successively analyze each A-scan to detect the presence of an A-scan feature associated with the object; separate the C-scan into B-scans; segment each of the B-scans to determine thresholds associated with the object; using a neural network, successively analyze each segmented B-scan to detect the presence of an B-scan feature associated with the object; convert the C-scan to one or more two-dimensional representations; and using a neural network, detect the presence of an C-scan feature associated with the object.

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 interference 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.

A single-beam three-degree-of-freedom homodyne laser interferometer based on an array detector. A single-frequency laser beam is input to a Michelson interference structure, the measurement beam and the reference beam perform non-coaxial interference and form a single-beam homodyne interference signal by setting the angle of a reference plane mirror, the array detector is selected to effectively receive the single-beam homodyne interference signal, and finally, three-degree-of-freedom signal linear decoupling on the single-beam homodyne interference signal is achieved through a three-degree-of-freedom decoupling method based on Lissajous ellipse fitting. The laser interferometer does is free of angle decoupling nonlinearity, the period nonlinear error is remarkably reduced, compared with other existing three-degree-of-freedom laser interferometers, the laser interferometer has the advantages of being simple in structure, large in angle measurement range and easy to integrate, and the high-precision requirement of the three-degree-of-freedom laser interferometer for displacement and angle measurement is met.

Source light having a range of optical wavelengths is generated. The source light is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes, each having a direct current (DC) component and at least one alternating current (AC) component. Different subsets of the optical modes of the interference light pattern are respectively detected, and analog signals representative of the optical modes of the interference light pattern are output. Pair of the analog signals are subtracted from each other, and differential analog signals are output. The sample is analyzed based on the differential analog signals.

The present disclosure provides an OCT imaging system having a variety of advantages. In particular, the OCT system of the present disclosure may provide a more intuitive interface, more efficient usage of controls, and a greater ability to view OCT imaging data.

An interferometer apparatus includes a beam splitter arranged for splitting an input beam into a first beam propagating along a first interferometer arm including a deflection mirror and a second beam propagating along a second interferometer arm including a deflection mirror. The first and second interferometer arms have an identical optical path length. A beam combiner is arranged for recombining the first and second beams into a constructive output and a destructive output. In the first interferometer arm compared with the second interferometer arm, one additional Fresnel reflection at an optically dense medium is provided and a propagation of the electromagnetic fields of the first and second beams, when recombined by the beam combiner, results in a wavelength-independent phase difference of π between the contributions of the two interferometer arms to the destructive output. Furthermore, an interferometric measurement apparatus and an interferometric measurement method are described.