An optoelectronic system for measuring physical parameters comprising: two narrow band light sources with different peak frequencies coupled together into a combined light using a coupler. The combined light is split into a first Fabry-P?rot interferometer arranged to be exposed to both temperature and physical parameter of interest and a second Fabry-P?rot interferometer arranged to be exposed only to temperature. The system further comprises first and second optical detectors arranged to receive light reflected from the cavities of the first and second Fabry-P?rot interferometers respectively through an optical path comprising a combination of lenses and/or mirrors and a Fizeau interferometer. A processor is arranged to analyze the data received by the first optical detector and second optical detector and calculate a value for temperature and the physical parameter of interest.

Inspecting a multilayer sample may include receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.

A displacement detecting device includes a first diffraction grating, a light source, a displacement detecting unit, and a light receiving unit. The displacement detecting unit includes a light flux dividing unit, a second diffraction grating, and a reference reflecting member. An incident angle of a first light flux to the first diffraction grating, a diffraction angle of the first diffraction grating, an incident angle of the first light flux to the second diffraction grating, and a diffraction angle of the second diffraction grating are angles at which a displacement amount in an optical path length of the first light flux from the light flux dividing unit to the first diffraction grating and a displacement amount in an optical path length of the first light flux from the first diffraction grating to the second diffraction grating become equal in a case where a measured member is displaced in a direction orthogonal to a measured surface.

Various balanced detection systems which reduce alignment requirements of free space optics based balanced detection configurations are discussed. One example system includes a light source, a beam divider, sample optics, return optics, and a processor. The light source generates a light beam. The beam divider separates the light beam into reference and sample arms. The sample optics deliver the light beam in the sample arm to a light scattering object to be imaged. The return optics direct light to a balanced detection system, which has a balanced detection beam divider for combining light scattered from the object and light from the reference arm and directing the combined light into two detection channels and two detectors for collecting the combined light in the two detection channels and generating signals in response thereto. The processor processes the signals and generates image data of the object based on the processed signals.

A position measurement system to measure a position of an object relative to a reference, the position measurement system including two interferometers, wherein each interferometer is configured to form a reference beam and a measurement beam from input radiation and to combine the reference beam and the measurement beam to provide output radiation to be delivered to a detector, wherein each interferometer is configured such that the reference beam is formed by reflection of input radiation from a reflective element, and such that the measurement beam is formed by diffraction of input radiation from a grating on the object, and wherein the reference beam and the measurement beam are parallel to each other.

The present invention provides a measurement apparatus for measuring a position of an object, comprising a reflecting portion provided on the object and having a surface on which reflectors configured to retroreflect light are arrayed, an optical system configured to cause first light to be incident on the surface, receive second light as reflected light of the first light, cause third light generated from the second light to be incident on the surface, and receive fourth light as reflected light of the third light, and a processor configured to determine the position of the object based on a detection result of the forth light, wherein the optical system is configured such that a displacement between optical paths of the first light and the second light is corrected by a displacement between optical paths of the third light and the fourth light.

An interferometer is provided that includes a single retroreflector arranged at a target plane and a plurality of retroreflectors arranged at a reference plane of the interferometer. The single retroreflector and the plurality of retroreflectors are positioned such that a measurement beam provided to the interferometer makes a plurality of passes between the single retroreflector and the plurality of retroreflectors. One of the plurality of retroreflectors is positioned as a terminal retroreflector that reflects the measurement beam back on itself such that an output of the interferometer is coaxial with an input to the interferometer.

A method for defect inspection of a transparent substrate comprises (a) providing an optical system for performing a diffraction process of object wave passing through a transparent substrate, (b) interfering and wavefront recording for the diffracted object wave and a reference wave to reconstruct the defect complex images (including amplitude and phase) of the transparent substrate, (c) characteristics analyzing, features classifying and sieving for the defect complex images of the transparent substrate, and (d) creating defect complex images database based-on the defect complex images for comparison and detection of the defect complex images of the transparent substrate.

An optical imaging device, including an imaging unit and a measuring device. The imaging unit includes a first optical element group having at least one first optical element, which contributes to the imaging. The measuring device determines an imaging error, which occurs during the imaging, using a capturing signal. The measuring device includes a measurement light source, a second optical element group and a capturing unit. The measurement light source emits at least one measurement light bundle, The second optical element group includes an optical reference element and a second optical element, which guide the measurement light bundle onto the capturing unit, to generate the capturing signal. Each second optical element has a defined spatial relationship with a respective one of the first optical elements, The second optical elements differ from the first optical elements. The measuring device determines the imaging error with the capturing signal.

A sample may be illuminated in such a way that light passes through the sample, reflects from a set of reflectors, passes through the sample again and travels to a light sensor. The reflectors may be staggered in depth beneath the sample, each reflector being at a different depth. Light reflecting from each reflector, respectively, may arrive at the light sensor during a different time interval than that in which light reflecting from other reflectors arrivesor may have a different phase than that of light reflecting from the other reflectors. The light sensor may separately measure light reflecting from each reflector, respectively. The reflectors may be extremely small, and the separate reflections from the different reflectors may be combined in a super-resolved image. The super-resolved image may have a spatial resolution that is better than that indicated by the diffraction limit.