Efficient interferometer designs for optical coherence tomography (OCT) systems are presented. One example interferometer design includes two polarization dependent beamsplitters and a non-polarization dependent combiner. The first polarization dependent beamsplitter transmits light in a first polarization state to a sample arm of the OCT system and transmits light in a second polarization state different from the first polarization state to a reference arm of the system. The second polarization dependent beamsplitter transmits light returning from a sample to the non-polarization dependent combiner. The combiner combines light returned from the sample and the light that has passed through the reference arm, which is then detected at a detector. Another example interferometer design includes free space optics comprising a non-reciprocal beamsplitting element in a beam path from a light source to a sample. The non-reciprocal beamsplitting element is implemented using a combination of a polarization dependent beamsplitter and a polarization manipulator.

Disclosed herein are optical integration technologies, designs, systems and methods directed toward Optical Coherence Tomography (OCT) and other interferometric optical sensor, ranging, and imaging systems wherein such systems, methods and structures employ tunable optical sources, coherent detection and other structures on a single or multichip monolithic integration. In contrast to contemporary, prior-art OCT systems and structures that employ simple, miniature optical bench technology using small optical components positioned on a substrate, systems and methods according to the present disclosure employ one or more photonic integrated circuits (PICs), use swept-source techniques, and employ a widely tunable optical source(s). In another embodiment the system uses an optical photonic phased array. The phase array can be a static phased array to eliminate or augment the lens that couples light to and from a sample of interest or can be static and use a spectrally dispersive antenna and a tunable source to perform angular sweeping. The phased array can be active in 1 or 2 dimensions so as to scan the light beam in angle. The phased array can also adjust focus. The phased array can implement an optical waveform that will extend depth of field focus for imaging. The phase array can also be a separate standalone element that is fed by one or more optical fibers. The phased array can be for scanning a biomedical specimen used in conjunction with a swept-source OCT system, can be used in a free-space coherent optical communication system for beam pointing or tracking, used in LIDAR applications, or many other beam control or beam steering applications.

An imaging system uses polarized light to illuminate the target and then uses a polarization filter to remove the light that is reflected from the target without modification. The target can include one or more anisotropic objects that scatter the light and alter the polarization state of the reflected light and causing it to be selectively transmitted to the imaging device which can record the transmitted light through the filter. The illuminating light can be circularly polarized and the filter can remove the circularly polarized light. The target can include asymmetric nanoparticles, such as nanorods that alter the amplitude or phase of the scattered light enabling pass through the filter to be detected by the imaging device.

A method, an interferometer, and a signal processing device, each for determining an input phase and/or an input amplitude of an input light field, are disclosed. Here, an input light field is divided into a first light field and a second light field by amplitude splitting. The first light field and the second light field are propagated such that the propagated second light field is defocused relative to the propagated first light field. The propagated first light field is superimposed on the propagated light field and caused to interfere.

An interferometer has a first input configured to provide a first measurement beam at a first frequency, and a second measurement signal at the first frequency. The interferometer has a second input configured to provide a reference beam at a second frequency that is different than the first frequency; an optical element comprising a first portion comprising a polarization beam splitter; and a diffraction grating disposed over the optical element configured to diffract the first measurement beam and the second measurement beam

The invention relates to an OCT system with an OCT light source for emitting OCT light into an object beam path and a reference beam path. The system comprises a detector for detecting an interference signal produced by the object beam path and the reference beam path. A polarization-dependent delay element is arranged in the object beam path. The invention also relates to a corresponding OCT method. The invention allows the effects of parasitic reflections to be reduced.

Optical coherence tomography (OCT) probe and system designs are disclosed that minimize the effects of mechanical movement and strain to the probe to the OCT analysis. It also concerns optical designs that are robust against noise from the OCT laser source. Also integrated OCT system-probes are included that yield compact and robust electro-opto-mechanical systems along with polarization sensitive OCT systems.

The embodiments herein relate to a method for deriving topography of an object surface. A linearly polarized light wave is directed towards the object surface and a reference surface. Images of reflected linearly polarized light wave for a plurality of wavelengths are obtained. The images are obtained for at least four polarizations for each of the plurality of wavelengths. The reflected linearly polarized light wave is a reflection of the linearly polarized light wave directed towards the object surface and the reference surface. The topography of the object surface based on the obtained images is obtained.

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.

A five-degree-of-freedom heterodyne grating interferometry system, comprising a single frequency laser device (1) and an acousto-optic modulator (2); the single frequency laser device (1) emits a single frequency laser, and the single frequency laser is coupled by optical fiber and, after being split, enters the acousto-optic modulator (2) to obtain two linearly polarized lights of different frequencies, one being a reference light, and one being a measurement light; an interferometer lens group (3) and a measurement grating (4), used for forming the reference light and the measurement light into a measurement interference signal and a compensation interference signal; and multiple optical fiber bundles (5), respectively receiving the measurement interference signal and the compensation interference signal, each optical fiber bundle (5) having multiple multi-mode optical fibers respectively receiving signals at different positions on the same plane. The present measurement system has the advantages of high measurement precision, a large measurement range, not being sensitive to temperature drift, and small overall size, and can be used as a photoetching machine ultra-precision workpiece table position measurement system.