The present specification relates to Master-Slave (MS) interferometry for sensing the axial position of an object subject to optical coherence tomography (OCT) imaging, and to MS-OCT applied to curved and axially moving objects. The methods and apparatuses allow producing OCT signals from selected depths within the object irrespective of its axial position in respect to the imaging system. Images are obtained for curved objects that are flattened along a layer of interest in the object, images that are used to provide OCT angiography images less disturbed by axial movement or lateral scanning.

The invention relates to a free-beam interferometric method for illuminating a sequence of sectional areas in the interior of the light-scattering object. The method makes it possible for the user to select a larger image field and/or a higher image resolution than previously possible with the occurrence of self-interference of the specimen light from a scattering specimen.

A method performs phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into an interferometer and while the wafer is vibrating. Additionally, a system and a non-transitory computer-readable storage medium have computer-executable instructions embodied thereon for performing phase shift interferometry to detect irregularities of a surface of a wafer after the wafer has been placed into an interferometer and while the wafer is vibrating.

Disclosed are several technical approaches of using low coherence interferometry techniques to create an autofocus apparatus for optical microscopy. These approaches allow automatic focusing on thin structures that are positioned closely to reflective surfaces and behind refractive material like a cover slip, and automated adjustment of focus position into the sample region without disturbance from reflection off adjacent surfaces. The measurement offset induced by refraction of material that covers the sample is compensated for. Proposed are techniques of an instrument that allows the automatic interchange of imaging objectives in a low coherence interferometry autofocus system, which is of major interest in combination with TDI (time delay integration) imaging, confocal and two-photon fluorescence microscopy.

Embodiments herein include swept-source interferometric imaging systems employing arbitrary sweep patterns in which a swept-source is swept over a continuous spectral range where the variation of wavelength over time is noncontinuous. Embodiments include sweep patterns that result in reduction of signals from moving scatterers and where the sweep is synchronized with the dead time of the camera.

The present system employs optical coherence tomography (OCT) or optical coherence microscopy (OCM) systems, including ultra-high resolution Gabor-domain optical coherence microscopy (GD-OCM), into a 3D flow imaging technique. This technique models the repeated scans as Gaussian latent variables, with the common variance representing both static tissue structure and dynamic blood flow, and the anisotropic unique variance representing tissue motion in specific frames. Since the motion generated variance is independent from that of the structure or the flow, by iteratively maximizing the combined log-likelihood probability of these two variances modeled through exploratory factor analysis, the unique variance (or the tissue motion) may be largely excluded. In the common variance, the dynamic blood flow may be separated from the static tissue structure, by integrating the factors that represent the relatively low levels of correlation. Compared to a direct differentiation of OCT or OCM scans, the present flow imaging algorithm improves the visualization of capillaries with reduced motion artifacts.

A system tracks eye movement using optical coherence in a head mounted display. The system includes an illumination source configured to project low coherence interference light onto a portion of a user's eye. The system includes a scanning system to select an axial position within the illuminated portion of the user's eye. The system includes a detector configured to collect light reflected from the illuminated portion of the user's eye at the selected axial position, and the reflected light includes measurement data characterizing the illuminated portion of the user's eye. The system includes a controller configured to compare the measurement data with a trained baseline, and determine an eye position based the comparison.

A light interference measuring device comprises: a light source 20 that outputs light; a beam splitter 222 that causes the light output from the light source to diverge into a reference optical path and a measurement optical path and that outputs a combined wave in which reflection light that has passed through the reference optical path and reflection light that has passed through a measuring object arranged in the measurement optical path are combined; a reference mirror 231 that is arranged in the reference optical path and that reflects light which is diverged into the reference optical path by the beam splitter 222; a stage 12 that is arranged in the measurement optical path and that has the work W placed thereon; an imaging part 25 that images an image in which the combined wave is formed; a reference mirror adjustment mechanism (234, 238, 239) that adjusts a posture of the reference mirror 231; and a control part that controls the reference mirror adjustment mechanism such that a reflecting surface of the reference mirror 231 corresponds to a measurement surface of the work W, based on an image imaged in a condition where a work W is placed on the stage.

In a method for interferometrically capturing measurement points of a region of an eye, a plurality of measurement points are captured by a measurement beam along a trajectory, wherein the same trajectory is passed over by the measurement beam in the region during at least a first iteration and a second iteration. The trajectory of the first iteration is rotated through an angle and/or displaced by a distance in relation to the trajectory of the second iteration in order to obtain a more homogeneous measurement point distribution.

A method for reducing motion artifacts in optical coherence tomography (OCT) angiography images is disclosed. The method is applied to the intensity or complex OCT data prior to applying the motion contrast analysis and involves determining sub-pixel level shifts between at least two B-scans repeated approximately at the same location and applying the sub-pixel level shifts to the B-scans to be able to correct for motion and accurately determine motion contrast signal. A preferred embodiment includes the use of 2D cross correlations to register a series of B-scans in both the axial (z-) and lateral (x-) dimensions and a convolution approach to achieve sub-pixel level frame registration.