A measurement apparatus for interferometric shape measurement of a test object surface. A test optical unit produces from measurement radiation a test wave for irradiating the surface. A reference element with an optically effective surface interacts with a reference wave also produced from the measurement radiation. An interferogram is produced by superimposing the test wave after interaction with the test object's surface. A holding device holds the reference element and moves the reference element relative to the reference wave in at least two rigid body degrees of freedom so that a peripheral point of the reference element's optically effective surface shifts by at least 0.1% of a diameter of the optically effective surface. The at least two degrees of freedom include a translational degree, directed transversely to a propagation direction of the reference wave and a rotational degree, whose rotational axis aligns substantially parallel to the reference wave's propagation direction.

Provided herein are interference objective modules comprising an objective, and an interference module comprising a reference plate disposed apart from the objective to provide a reference arm, a beam splitter to split a source light processed from the objective, and a sample plate to translate the split light from the beam splitter to provide a sample arm, wherein the interference module is configured to make a distance of a focal plane and an interference plane of the interference objective module varied during a measurement, and wherein the focal plane and the interference plane of the interference objective module intersect during the measurement.

A wavelength-swept light source projects a light beam. An interferometer includes a splitting unit that splits the light beam projected from the wavelength-swept light source into light beams radiated toward a plurality of spots on a measurement target. Each of the interference beam is generated by interference between a measurement beam radiated toward the measurement target and reflected at the measurement beam, and a reference beam passing through an optical path that is at least partially different from an optical path of the measurement beam. A light-receiving unit receives the interference beams from the interferometer. A processor calculates distance to the measurement target by associating a detected peak of the interference beams with one of the spots. The optical path length difference between the measurement target and the reference beam is made different among the light beams split in correspondence with the plurality of spots.

The technology disclosed in this patent document can be used to implement an optical coherent tomography (OCT) system that combines a control of the probe light to the target sample with different optical aberration patterns in optically probing the target sample and an OCT imaging processing to enhance the OCT imaging quality by combining image signals from in-phase contributions from the probing with different optical aberration patterns while suppressing randomly phased contributions from scattering by the target sample.

A light source projects a light beam. An interferometer includes a splitting unit that splits the light beam. The interferometer generates interference beams with the respective split light beams. Each of the interference beam is generated by interference between a measurement beam radiated toward the measurement target and reflected at the measurement beam and a reference beam passing through an optical path. A light-receiving unit receives the interference beams. A processor calculates a distance to the measurement target by associating at least one detected peak with at least one of the spots in accordance with a mirror surface mode or a rough surface mode. The optical path length difference is made different among the split light beams. In the mirror surface mode, the processor uses a distance calculated based on a peak corresponding to a spot for which the optical path length difference is shortest.

An OCT imaging system may include an OCT light source operable to emit an OCT light beam, and a beam splitter operable to split the OCT light beam into a sample beam, transferred to a sample arm waveguide, and a reference beam, transferred to a reference arm waveguide. The sample arm waveguide and the reference arm waveguide may be coupled together within a cladding, wherein the cladding improves a calibration of a generated OCT image by fixing axial movement of the sample arm and reference arm waveguides relative to one another. By routing long reference and sample arm waveguide fibers together in the OCT system using a sheath/cladding, OCT image offset due to asymmetrical fiber stretching can be minimized or eliminated.

One or more devices, systems, methods and storage mediums for performing common path optical coherence tomography (OCT) with a controlled reference signal and efficient geometric coupling are provided. Examples of such applications include imaging, evaluating and diagnosing biological objects, such as, but not limited to, for Gastro-intestinal, cardio and/or ophthalmic applications, and being obtained via one or more optical instruments, such as, but not limited to, optical probes (e.g., common path probes), common path catheters, common path capsules and common path needles (e.g., a biopsy needle). Preferably, the OCT devices, systems methods and storage mediums include or involve a reference reflection or a reference plane that is at least one of: (i) disposed in the collimation field or path; and (ii) is perpendicular (or normal) or substantially perpendicular (or substantially normal) to light propagation. One or more embodiments may include beam shaping optics to properly image luminal or other hollow structures or objects.

The present invention provides a reflective condensing interferometer for focusing on a preset focus. The reflective condensing interferometer includes a concave mirror set, a convex mirror, a light splitting element, and a reflecting element. The concave mirror set has first and second concave surface portions which are oppositely located on two sides of a central axis passing through the preset focus and are concave on a surface facing the central axis and the preset focus. Light is preset to be incident in parallel to the central axis in use. The convex mirror is disposed between the concave mirror set and the preset focus on the central axis, and is convex away from the preset focus. The light splitting element vertically intersects with the central axis between the convex mirror and the preset focus. The reflecting element is disposed between the light splitting element and the convex mirror.

The present invention provides a reflective condensing interferometer for focusing on a preset focus. The reflective condensing interferometer includes a concave mirror set, a convex mirror, a light splitting element, and a reflecting element. The concave mirror set has first and second concave surface portions which are oppositely located on two sides of a central axis passing through the preset focus and are concave on a surface facing the central axis and the preset focus. Light is preset to be incident in parallel to the central axis in use. The convex mirror is disposed between the concave mirror set and the preset focus on the central axis, and is convex away from the preset focus. The light splitting element vertically intersects with the central axis between the convex mirror and the preset focus. The reflecting element is disposed between the light splitting element and the convex mirror.

The invention relates to the field of interferometry, in particular to Fizeau interferometers for improving a contrast of an interferogram. The Fizeau interferometer comprises a light source, a reference surface, a test surface positioned in on a support of the Fizeau interferometer and an imaging system. The Fizeau interferometer utilizes a polarizing reference surface to improve the contrast of the interferogram. The invention further relates to a method for using the Fizeau interferometer of the invention for improving contrast of an interferogram obtained by the Fizeau interferometer.