In some embodiments, systems, methods, and media for multiple reference arm spectral domain optical coherence tomography are provided which, in some embodiments, includes: a sample arm coupled to a light source; a first reference arm having a first path length; a second reference arm having a longer second path length; a first optical coupler that combines light from the sample arm and the first reference arm; a second coupler that combines light from the sample arm and the second reference arm; and an optical switch comprising: a first input port coupled to the first optical coupler; a second input coupled to the second coupler via an optical waveguide that induces a delay at least equal to an acquisition time of an image sensor; and an output coupled to the image sensor.

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.

An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

The present invention aims to obtain a tomographic image free from image noise due to reflection on a container wall surface and having a good image quality by a simple configuration. In a FD-OCT imaging apparatus which images an imaging object stored in a container having an optical transparent wall part tomographically, when the focal depth is set such that a distance D from a first surface Sa of the wall part on the side of the imaging object to a focal point FP of the objective optical system is smaller than a predetermined threshold value smaller than a thickness T of the wall part, the distance between a second surface Sb of the wall part on a side opposite to the imaging object out of the wall surfaces and a reference plane which is perpendicular to the optical path of the illumination light and to which an optical path length is equal is set a value equal to the thickness of the wall part.

An optical coherence tomography (OCT) system electrically mixes a signature signal with an OCT signal (e.g., an interferogram) output by a photodetector of the OCT system. The signature signal may be a signal output by a photodetector that detects an optical signal from a fiber Bragg grating. The signature signal may then be time delayed before combination with the OCT signal. A series of interferograms are then aligned according to the signature signal. A rescaling signal may be similarly electrically mixed with the signature and OCT signals.

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 aims to obtain a tomographic image free from image noise due to reflection on a container wall surface and having a good image quality by a simple configuration. In a FD-OCT imaging apparatus which images an imaging object stored in a container having an optical transparent wall part tomographically, when the focal depth is set such that a distance D from a first surface Sa of the wall part on the side of the imaging object to a focal point FP of the objective optical system is smaller than a predetermined threshold value smaller than a thickness T of the wall part, the distance between a second surface Sb of the wall part on a side opposite to the imaging object out of the wall surfaces and a reference plane which is perpendicular to the optical path of the illumination light and to which an optical path length is equal is set a value equal to the thickness of the wall part.

An OCT apparatus includes an OCT optical system that has a light splitter splitting light from an OCT light source to light travelling to a measurement light path and light travelling to a reference light path and a detector detecting a spectrum interference signal of measurement light guided to a subject eye through the measurement light path and reference light from the reference light path, and a processing unit that processes the spectrum interference signal to generate OCT data. The processing unit performs at least complementary processing on an overlapping region of a real image and a virtual image in OCT data based on a plurality of OCT data obtained with different optical path lengths when detecting the spectrum interference signal, and generates OCT data subjected to the complementary processing.

An efficient OCT data collection and processing method for obtaining a high-axial-resolution image with explicit ranging over an extended depth is described. The method includes collecting a first dataset at a transverse location of the sample. The first dataset comprises spectra of a bandwidth (k.sub.1) sampled at a spectral sampling interval (dk.sub.1). A second dataset comprising spectra of a bandwidth (k.sub.2) sampled at a spectral sampling interval (dk.sub.2) is collected. The bandwidth k.sub.2 is less than k.sub.1 and spectral sampling interval dk.sub.2 is less than dk.sub.1. The first and the second datasets are processed to generate at least one A-scan with an axial resolution higher than the axial resolution corresponding to the bandwidth k.sub.2 and a depth range larger than the depth range provided by sampling interval dk.sub.1.

A metrology apparatus has an illumination source that directs collimated light to a reference surface and to an optical component having a test surface that is in parallel with the reference surface. A first imaging lens defines a Fourier transform plane for light reflected from the reference surface and the test surface. A spatial filtering element is actuable to a blocking position that blocks specular light at the transform plane. A second imaging lens forms, at an image plane, an image of the test surface. A sensor array generates image data from received light at the image plane.