A probe for an optical measurement system includes a probe body arranged to be adjustably mounted in a measuring machine for optically measuring a test object. A polarizing fiber optically coupled within the probe body transmits a source beam having an instantaneous or sequentially established bandwidth spanning a range of wavelengths to the probe body and also transmits a measurement beam from the probe body toward a detector. An adjustable beam manipulator is provided for angularly redistributing the reference beam along the reference arm.

An optical coherence tomography system, includes a swept-source laser, a Mach-Zehnder interferometer and a balanced detector. The interferometer includes a first fiber coupler, a second fiber coupler, a sample arm and a reference arm. The reference arm includes a reference arm front section, a reference arm rear section and a delay line. A tail end of the reference arm front section is connected to the reference arm rear section through the delay line. The first fiber coupler is configured to split the output light of the swept-source into a sample light and a reference light and distribute the returned sample light to the second fiber coupler. A difference between the optical path length of a parasitic reflected signal of the delay line reaching the second fiber coupler and the optical path length of the sample light is greater than 8 times the cavity length of the swept-source laser.

An optical interferometer includes a branching-combining unit, a first optical system, a second optical system, and a drive unit. The branching-combining unit includes a branching surface, an incident surface, a first output surface, a combining surface, and a second output surface on an interface of a transparent member, the branching surface partially reflects incident light and outputs as first branched light, and transmits the rest of the incident light into the interior as second branched light, the combining surface partially combines the first branched light and the second branched light to be output to the outside as first combined light, and combines the rest of the first branched light and the second branched light to be propagated into the interior as second combined light, and the second output surface partially outputs the second combined light to the outside.

A method is disclosed for operating an endpoint detection system of a processing chamber having a ceiling formed therein, a substrate support located internal to the processing chamber, and a substrate resting on the substrate support. A transparent panel is located in the ceiling of the processing chamber, the panel oriented at a first acute angle relative to the substrate and the substrate support. The transparent panel receives an incident light beam from the endpoint detection system at a second acute angle relative to the panel. The transparent panel transmits the incident light beam to the substrate within the processing chamber at an angle perpendicular to the substrate and the substrate support.

A light interference unit includes a branching optical element, a multiplexing optical element, and at least one fiber device. The branching optical element branches a laser light with an emission wavelength temporally swept, into a measurement light and a reference light. The multiplexing optical element multiplexes the reference light and the measurement light reflected by a measured object, and causes them to interfere. The fiber device includes a reference light device. A transmission light path length is a light path length of the reference light transmitting the reference light device, from the reference light device to the multiplexing optical element. A reflection light path length is a light path length of the reference light reflected by a separation portion of the reference light device, from the reference light device to the multiplexing optical element. The transmission light path length is equal to or more than the reflection light path length.

An optical detector system comprises a hermetic optoelectronic package, an optical bench installed within the optoelectronic package, a balanced detector system installed on the optical bench. The balanced detector system includes at least two optical detectors that receive interference signals. An electronic amplifier system installed within the optoelectronic package amplifies an output of at least two optical detectors. Also disclosed is an integrated optical coherence tomography system. Embodiments are provided in which the amplifiers, typically transimpedance amplifiers, are closely integrated with the optical detectors that detect the interference signals from the interferometer. Further embodiments are provided in which the interferometer but also preferably its detectors are integrated together on a common optical bench. Systems that have little or no optical fiber can thus be implemented.

An interferometer system, including a heterodyne interferometer and a processing system. The heterodyne interferometer is arranged to provide a reference signal and a measurement signal. The reference signal has a reference phase. The measurement signal has a measurement phase and an amplitude. The processing system is arranged to determine a cyclic error of the heterodyne interferometer based on the reference phase, the measurement phase and the amplitude.

A device for determining a 3D structure of an object having first and second laser emitters which generate laser radiation with first and second different wavelengths, respectively. A first beam splitter splits the laser radiation of each laser emitter into reference and illuminating radiation. The illuminating radiation is adapted to impinge on the object to be measured, be reflected by the object as object radiation, and interfere with the reference radiation to form interference patterns. A detector receives the interference patterns. A selection hologram deflects object radiation which impinges on it within a predefined incidence angle range and passes object radiation which impinges on it outside of the incidence angle range undiffracted. The undiffracted radiation either passes by the determination area of the detector or impinges on the determination area at an angle outside the determination angle range.

Generally, in accordance with the various illustrative embodiments disclosed herein, a heterodyne optical interferometer incorporates error correction elements to correct a cyclic error that may be present in an interferometric measurement. The cyclic error can be caused by various factors such as an imperfect polarization relationship between two wavelength components, deficiencies in optical propagation paths (such as light leakage), imperfect optical coatings, and/or imperfect components. The cyclic error, which typically manifests itself as erroneous displacement information characterized by a low velocity sinusoidal frequency component, can be reduced or eliminated by using birefringent optical elements and other optical elements to alter certain characteristics of one or both wavelength components and reduce light leakage components in one or more light propagation paths in the heterodyne optical interferometer.

The present invention provides a measurement apparatus for measuring a shape of a test surface, comprising an optical system configured to irradiate a measurement point on the test surface and a reference surface with light, and cause test light and reference light reflected to interfere with each other, a detector configured to detect an optical path length difference between the test light and the reference light by using interfering light and a processor configured to determine a position of the measurement point based on a plurality of detection results by the detector, wherein a detection result includes an error which cyclically changes, and the plurality of detection results include n detection results obtained in n states in which optical path lengths of the test light are different from each other by 1/n (n2) of a cycle of the error.