Disclosed are a device and a method for measuring laser displacement. The device comprises an interferometric measurement module, a laser light source module, a signal modulation module, a control processing module and an optical vernier demodulation module. The control processing module controls the signal modulation module to apply a light source modulation signal to the laser light source module, so that the laser light source module provides two laser beams with fixed frequency difference to the interferometric measurement module. The control processing module controls the interferometric measurement module to perform interferometric measurement. During measurement, lasers respectively interfere in two Fabry-Perot cavities in the interferometric measurement module, and are detected by two photodetectors to form main and secondary measurement interference signals. The optical vernier demodulation module demodulates the main and secondary measurement interference signals obtained by the interferometric measurement module.

Improved optical coherence tomography systems and methods to measure thickness of the retina are presented. The systems may be compact, handheld, provide in-home monitoring, allow the patient to measure himself or herself, and be robust enough to be dropped while still measuring the retina reliably.

A first light source outputs measurement light having a wavelength in infrared range. A second light source outputs guide light having a wavelength in visible range. A fiber coupler includes a first port into which the measurement light is input, a second port into which the guide light is input, and a third port outputting combined light formed by combining the measurement light and the guide light with each other. A measurement unit emits the combined light to a measurement object and receives return light reflected therefrom. A processing unit obtains information relating to a distance, a speed, or an oscillation of the measurement object, based on an interference signal of the return light and the reference light. The fiber coupler is formed by a single mode fiber that has a cutoff wavelength that is shorter than that of the measurement light and longer than that of the guide light.

A system for precision displacement measurement based on a self-traceable grating interference includes a coherent light source, a photoelectric detection module, a self-traceable grating and a signal processing module. The self-traceable grating is arranged on a to-be-measured displacement motion platform. The coherent light source, the photoelectric detection module and the signal processing module are sequentially connected. Laser generated by the coherent light source propagates through the photoelectric detection module and is incident on the self-traceable grating, diffracts with the self-traceable grating, returns to the photoelectric detection module to continue propagating and enters the signal processing module. The signal processing module collects an interference signal to obtain a motion displacement and a motion direction.

A digital measuring device implemented on a photonic integrated circuit, the digital measuring device including a laser source configured to provide light, a first ring resonator configured to produce a first frequency comb of light from the laser source, wherein at least a portion of the first frequency comb of light is directed at a moving object, a local oscillator configured to provide a reference beam, at least one waveguide structure configured to combine the reference beam with light reflected from the moving object to produce a measurement beam, a first multiplexer configured to split the measurement beam into a plurality of channels spaced in frequency, and a plurality of detectors configured to detect an intensity value of each channel of the plurality of channels to measure a distance between the digital measuring device and the moving object.

The invention refers to an optical device for heterodyne interferometry, comprising a chip, a beam splitter, a first waveguide arranged on the chip, light propagating in the first waveguide being guided to the beam splitter, a second waveguide arranged on the chip, light propagating in the second waveguide being guided to and/or from the beam splitter, wherein the beam splitter, the first waveguide, and the second waveguide form part of a Michelson interferometer, wherein the first waveguide and the second waveguide at least partially form two arms of the Michelson interferometer, and wherein two further arms of the Michelson interferometer are at least partially arranged outside the chip.

Methods and systems of eliminating corrupting influences caused by the propagation medium and the data capture devices themselves from useful image features or characteristics such as the degree of symmetry are disclosed. The method includes the steps of obtaining image-plane data using a plurality of data capture devices, wherein the image-plane data is a combined visibility from each of the data capture devices, measuring the closure phase geometrically in the image-plane directly from the image-plane, removing the corruptions from the image features based on the measured closure phase to remove the non-ideal nature of the measurement process, and outputting the uncorrupted morphological features of the target object in the image. The method relies on the Shape-Orientation-Size conservation principle for images produced from three visibilities made from a closed triad of data capture devices. The method includes the idea that true image of the object can be reconstructed from the three interferometer elements, independent of element-based calibration.

A composite measurement system for measuring nanometer displacement is provided. The system includes: a light source, a polarization beam splitting prism, a first phase change module, a second phase change module, a first right-angle prism, a second right-angle prism, a non-polarization beam splitting prism, a scalar interference light collection module, a vector interference light collection module and a displacement calculation module. In the present disclosure, a photodetector is configured to collect an intensity of scalar interference light of the object to be measured being moving, to obtain a periodic light intensity change curve; a CCD camera is configured to collect images of interference vortex light of the object being moving; and the displacement calculation unit is configured to calculate a displacement of the object according to integer periods of the light intensity change curve and angles of image changes of the interference vortex light.

A device and method for measuring a surface of an object, including at least one light source, at least one optical sensor, and an interferometry device having a measurement arm and a reference arm, the former directing light from each light source towards the surface of the object and directing light from the surface towards each optical sensor; the measurement device, in an interferometry configuration, illuminating the reference arm and the measurement arm with each light source and directing the light from the measurement arm and the reference arm towards each optical sensor to form an interference signal; the measurement device, in an imaging configuration illuminating at least the measurement arm and directing the light from the measurement arm towards the optical sensor to form an image of the surface; the measurement device including a digital processor producing, from the interference signal and the image, information on the surface.

The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length. The interferometer system comprises: a beam splitter to split a light beam in a first measurement beam and a second measurement beam; at least one optic element to guide the first measurement beam, at least partially, along the first reflection path and the second measurement beam, at least partially, along the second reflection path; a first light sensor arranged at an end of the first reflection path to receive the first measurement beam and to provide a first sensor signal on the basis of the first measurement beam; a second light sensor arranged at an end of the second reflection path to receive the second measurement beam and to provide a second sensor signal on the basis of the second measurement beam; and a processing unit to determine a wavelength or change in wavelength on the basis of the first sensor signal and the second sensor signal.