A method of rapid coherent synthetic wavelength interferometric absolute distance measurement includes receiving, from an optical system, an image from an object scene of at least two distinct wavelengths of light, each wavelength's light source having a coherence length greater than a desired ambiguity length of the absolute distance measurement, and whose synthetic wavelength in combination provides the desired ambiguity length of the absolute distance measurement. A phase-based approach, a magnitude-based approach, or an envelope of the magnitude-based approach can be taken to determine an interference between light returning from the object scene and light traversing a separate reference arm path of the optical system and calculate an optical distance to an object in the object scene.

A polarization-separated, phase-shifted interferometer can generate interferograms without moving parts. It uses a phase shifter, such as an electro-optic phase modulator, to modulate the relative phase between sample and reference beams. These beams are transformed into orthogonal polarization states (e.g., horizontally and vertically polarized states) and coupled via a common path (e.g., polarization-maintaining fiber) to a polarizing beam splitter (PBS), which sends them into separate sample and reference arms. Quarter-wave plates in the sample and reference arms rotate the polarization states of the sample and reference beams so they are coupled out of the PBS to a detector via a 45? linear polarizer. The polarizer projects the aligned polarization components of the sample and reference beams onto the detector, where they interfere with known relative phase to produce an output that can be used to map surface topography of the test object.

An interference fringe projection apparatus includes light source units that selectively emit light from a coherent light source from one of a plurality of optical emitters, a polarization-maintaining waveguide unit with a plurality of PANDA fibers (polarization-maintaining waveguides) that each guide light emitted from one of the plurality of optical emitters, polarization splitters that split an optical path of light emitted from each of the PANDA fibers by polarization direction, and a polarizing film that transmits only a linear polarization component in a particular direction of light split by the polarization splitter. The light source unit only emits linearly polarized light in one polarization-maintaining direction for at least one of the PANDA fibers, and the polarization-maintaining waveguide unit causes retardation of light emitted from the PANDA fibers to vary.

Provided are improved optical detection systems and methods for using same, which systems and methods comprise single channel interferometric detection systems and methods for determining a characteristic property of samples. Such interferometric detection systems and methods employ a light beam that impinges two or more discrete zones along a channel, thereby avoiding variations that can result in increases in detection limits and/or measurement errors.

Herein is provided a simplified method for performing multiple wavelength phase shift interferometry measurements that is implemented by modulating each of the monochromatic light sources with a different carrier frequency, combining them to a single beam, detecting all wavelengths simultaneously using the same detectors and separating them via Fourier analysis and demodulation of the data. This approach offers both a simplification to the optical system and reduces the duration of time required to perform the multiple wavelength measurement, based on a simple data extraction algorithm decoding the information for each wavelength. When combined with the parallel phase shift orthogonal polarization interferometric microscopy this method provides fast, stable, high precision 3D imaging and displacements sensing. Also disclosed are embodiments of optical systems designed to carry out the method.

An example system includes a master oscillator that provides a master oscillator beam, a first fiber beam splitter that splits the master oscillator beam into a first branch and a second branch, a second fiber beam splitter that splits the first branch into an imaging branch and an amplified characteristic branch, and a compensation branch mixer that mixes the second branch and the amplified characteristic branch into a compensation branch. The example system includes transmission optics that direct the imaging branch to a target location, an imaging mixer that mixes the compensation branch and a reflected image from the target location into an imaging signal, and an acquisition device that receives the imaging signal as a final image. An example system optionally includes a mode matching lens that applies a selected wavefront characteristic to the compensation branch.

Described herein are systems and methods for optical coherence tomography with a centimetric range of scan depth and a high tolerance of a precision of lengths among different optical components. A system includes a long coherent light source, an optical interferometer with multiple optical components, an optical detector with a wide bandwidth, a data acquisition unit with high sampling rate, and a data processing unit to process information of interest.

A microstructured optical fiber for generating supercontinuum light. The optical fiber includes a core and a cladding region surrounding the core. The optical fiber includes a first fiber length section, a second fiber length section as well as an intermediate fiber length section between said first and second fiber length sections. The first fiber length section has a core with a first characteristic core diameter larger than about 7 ?m. The second fiber length section has a core with a second characteristic core diameter, smaller than said first characteristic core diameter. The intermediate length section of the optical fiber includes a core which is tapered from said first characteristic core diameter to the second characteristic core diameter over a tapered length. Also, a supercontinuum light source including an optical fiber and a pump light source.

A high-resolution handheld OCT imaging system related to the optical imaging field solves the issues of handheld OCT systems with low resolution and the inability to measure the skin's stratum corneum thickness accurately. Through adopting the visible wavelength band of supercontinuum laser as the light source, mainly applying reflectors instead of lenses in the OCT system, and replacing fiber propagation with optical propagation in free space in the interference optical paths, to significantly reduce dispersion loss in the axial resolution and improve the axial resolution of OCT systems. The filter, attenuator, grating, camera, and other components are separated from the handheld module through modular design to reduce the handheld terminal's size and weight and realize the system construction. The invention improves the axial resolution, obtains the thickness information of whole-body skin's stratum corneum, and provides technical approaches for skin diagnosis and related medicine development.

An optical coherence tomography system which is capable of operating in two or more optical bandwidth configurations for the purpose of trading off between high resolution imaging and high signal-to-noise ratio imaging, wherein the later enables deeper imaging depth. The system and associated methods allow for both high resolution, shallow penetration depth and low resolution, deep penetration depth optical coherence tomography imaging to be performed using a single light source. Methods and apparatus are described that allow a single system to dynamically switch between modes, or to operate in a hybrid mode that achieves a balance between resolution and SNR/depth of penetration.