A three-dimensional measurement device includes: an optical system that splits incident light into two lights and radiates lights to a measurement object and to a reference surface, and recombines the two lights to emit combined light; a first irradiator that emits first light including first polarized light and entering a first surface; a second irradiator that emits second light including second polarized light and entering a second surface; a first imaging system to which the first output light enters wherein the first output light is emitted from the first surface when the first light enters the first surface; a second imaging system to which the second output light enters wherein the second output light is emitted from the second surface when the second light enters the second surface; and an image processor that performs three-dimensional measurement based on interference fringe images obtained by the first and second imaging systems.

The present invention is aimed at providing measurement method for vibration displacement using state variation principle which achieves real time implementation through super high-speed DSP or FPGA as well as improves precision as much as picometer level and at the same time saves memory capacity compared to conventional invention.

An optical metrology device, such as an interferometer, detects sub-resolution defects on a sample, i.e., defects that are smaller than a pixel in the detector array of the interferometer. The optical metrology device obtains optical metrology data at each pixel in at least one detector array and determines parameter values of a signal model for a pixel of interest using the optical metrology data received by a plurality of pixels neighboring a pixel of interest. A residual for the pixel of interest is determined using the optical metrology data received by the pixel of interest and determined parameter values for the signal model for the pixel of interest. A defect, which may be smaller than the pixel of interest can then be detected based on the residual for the pixel of interest.

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 three-dimensional measurement device includes: an optical system that splits incident light into two lights, radiates one of the two lights as measurement light to a measurement object and the other as reference light to a reference surface, and recombines the two lights to emit combined light; a first irradiation unit that emits first light entering the optical system; a second irradiation unit that emits second light entering the optical system; a first imaging unit into which output light that is obtained from the first light and is emitted from the optical system enters; a second imaging unit into which output light that is obtained from the second light and is emitted from the optical system enters; and an image processor that executes three-dimensional measurement of the measurement object, based on interference fringe images taken by the first imaging unit and the second imaging unit.

An optical system includes a polarized light phase shift optical circuit that includes a polarizing beam splitter that splits light having a coherence length shorter than a difference in optical path length between a normal optical path and a delay optical path having an optical path length longer than the normal optical path, the light being split into normal light, which travels along the normal optical path, and delay light, which travels along the delay optical path; a separator where the normal light and the delay light are individually emitted at a reference flat and the separator divides the reflected light that reflects off the reference flat into a plurality of light beams; and a plurality of image capture elements that respectively detect the intensities of the plurality of divided light beams, and the optical system also includes an information processor that includes a calibrator.

Systems and methods are described herein for a self-referencing interferometer. The interferometer can comprise an improved spatial phase shifter that reduces the number of components, size and complexity of the spatial phase shifter and maintains a common path for a combined reference beam and signal beam. The self-referencing interferometer further comprises a single mode fiber shunt for filtering the reference beam and further reducing the size of the interferometer. The angle of the reference beam can be tilted before being recombined with the single beam which further simplifies the spatial phase shifting component of the interferometer.

The invention is a system and method that enable obtaining ultra-high resolution interference, phase and OCT images at high speed. The system uses neither mechanical moving elements nor any optical/electro optical modulating means for obtaining the OCT images. Two OCT operating modes are available: for ultra-high resolution the system allows either spatial coherence TD-FF-OCT or temporal coherence TD-FF-OCT imaging, whereas for high resolution and ultra-high speed the system allows FD-FF-OCT imaging with full range imaging. In the TD mode, the OCT enface images are obtained in real time. In the FD mode, the 2D complex signal is reconstructed in real time. In both cases the method has the advantage of very high speed imaging with great immunity to noise.

The thickness of an at least partially transparent layer is measured using wavelength band limited light, with a coherence length that is less than twice the thickness of the layer. Reflections from layer are fed to a 2-n coupler (n>2) via optical transmission paths of different optical length. The 2-n coupler mix light from the path into n combinations of light from the paths, each combination with a different mutual phase offset between the light from the two paths. This leads to coherent interference between reflections from the front and back of the layer when the difference between the optical lengths of the optical transmission paths compensates for the path between reflection from the front and the back. A processing circuit computes information indicative of a phase difference between the reflections from n intensities of the 2-n coupler. The use of n>2 signals makes it possible to eliminate the influence of reflection amplitude variations on the computed phase difference.

An interferometric displacement measurement apparatus (100) includes at least one measurement interferometer (103) for measuring a change in optical path difference between a measurement beam (150) and a reference beam. A light source module (118) is arranged to generate a modulated light beam, having a particular optical spectrum, from which the measurement beam and reference beam are derived. A data acquisition and analysis module (105) can determine a measure representative of the displacement using interference intensity data received from a photodetector (111) which detects the interference of the measurement beam with the reference beam.