Systems, devices and methods for measuring surface roughness and surface shape of an optical element using a dual-mode interferometer are disclosed. The devices implement optical filters, with a compact form, that allows measurement of both surface characteristics without rearranging the system components. One example interferometric system includes a laser light source and a low coherence light source that alternatively provide light to a collimator, followed by a polarizer, and a polarizing beam splitter. The system further includes two optical filters, a quarter waveplate, two objectives and a reference optical component. Each light source produces a set of interferograms, where one set of interferograms is used to measure the surface shape and another set of interferograms is used to measure the surface roughness of the optical component.

Provided herein are devices and systems comprising an illumination module configured to provide a source light to an optical interference module, which converts the source light to a line of light and processes light signal; an interference objective module, which handles light from the optical interference module and processes light signal generated from a sample; a two-dimensional camera configured to receive a backscattered interference signal from the sample, and a data processing module which processes the interference signal into an image.

An interferometer includes a light source, a beam splitter, a reference reflector, a measuring reflector, a detection unit, and at least two transparent plane-parallel plates. The beam splitter splits a beam of rays into at least one measuring beam and at least one reference beam. Until being recombined, the measuring beam propagates in a measuring arm, and the reference beam propagates in a reference arm. The reference beam falls at least three times on the reference reflector located in the reference arm. The measuring reflector is disposed in the measuring arm and is joined to an object to be measured, which is movable along a measuring direction relative to the reference reflector. The measuring beam falls at least three times on the measuring reflector. At least one distance signal with regard to the position of the object to be measured is ascertainable from the interfering measuring and reference beams via the detection unit. The plane-parallel plates are disposed parallel to each other in the beam path between the light source and the detection unit. At least the measuring reflector is movable relative to the plane-parallel plates along the measuring direction. The plane-parallel plates each include a plurality of optical elements that exert such an optical effect on the measuring beam and the reference beam that they propagate parallel to each other in the direction of the measuring reflector and reference reflector, respectively.

An image capturing apparatus for capturing an image of a workpiece held on a chuck table includes a camera, an objective lens having a minute hole defined centrally therein and disposed in facing relation to the workpiece held on the chuck table, an optical fiber having an end inserted in the minute hole in the objective lens, a light source optically coupled to another end of the optical fiber, and a beam splitter disposed in the optical fiber for branching off returning light reflected by the workpiece held on the chuck table. The image capturing apparatus further includes a calculating section for calculating a value representing a height or a thickness of the workpiece on the basis of the returning light branched off by the beam splitter, and a focusing mechanism for focusing the objective lens on the workpiece on the basis of the value calculated by the calculating section.

Efficient interferometer designs for optical coherence tomography (OCT) systems are presented. One example interferometer design includes two polarization dependent beamsplitters and a non-polarization dependent combiner. The first polarization dependent beamsplitter transmits light in a first polarization state to a sample arm of the OCT system and transmits light in a second polarization state different from the first polarization state to a reference arm of the system. The second polarization dependent beamsplitter transmits light returning from a sample to the non-polarization dependent combiner. The combiner combines light returned from the sample and the light that has passed through the reference arm, which is then detected at a detector. Another example interferometer design includes free space optics comprising a non-reciprocal beamsplitting element in a beam path from a light source to a sample. The non-reciprocal beamsplitting element is implemented using a combination of a polarization dependent beamsplitter and a polarization manipulator.

A system for providing optical actuation and optical sensing can include an optical coherence tomography (OCT) device that performs optical imaging of a sample based on optical interferometry from an optical sampling beam interacting with an optical sample and an optical reference beam; an OCT light source to provide an OCT imaging beam into the OCT device which splits the OCT imaging beam into the optical sampling beam and the optical reference beam; and a light source that produces an optical actuation beam comprising a plurality of wavelengths that is coupled along with the optical sampling beam to be directed to the sample to actuate particles or structures in the sample so that the optical imaging captures information of the sample under the optical actuation.

A method of detecting the positions of a plurality of probes. An input beam is directed into an optical device and transformed into a plurality of output beamlets which are not parallel with each other. Each output beamlet is split into a sensing beamlet and an associated reference beamlet. Each of the sensing beamlets is directed onto an associated one of the probes with an objective lens to generate a reflected beamlet which is combined with its associated reference beamlet to generate an interferogram. Each interferogram is measured to determine the position of an associated one of the probes. A similar method is used to actuate a plurality of probes. A scanning motion is generated between the probes and the sample. An input beam is directed into an optical device and transformed into a plurality of actuation beamlets which are not parallel with each other.

Some embodiments are directed to a technique having an off-axis interferometric geometry that is capable of spatially multiplexing at least six complex wavefronts, while using the same number of camera pixels typically needed for a single off-axis hologram encoding a single complex wavefront. Each of the at least six parallel complex wavefronts is encoded into an off-axis hologram with a different fringe orientation, and all complex wavefronts can be fully reconstructed. This technique is especially useful for highly dynamic samples, as it allows the acquisition of at least six complex wavefronts simultaneously, optimizing the amount of information that can be acquired in a single camera exposure. The off-axis multiplexing holographic system of some embodiments provide an off-axis holography modality that is more camera spatial bandwidth efficient than on-axis holography. Moreover, the off-axis interferometric system allows simple simultaneous acquisition of at least six holographic channels, making it attractive for imaging dynamics.

In an optical position measuring device for detecting the relative position of a first measuring standard and a second measuring standard, movable relative to each other along at least one measuring direction, at a splitting grating, a beam bundle emitted by a light source is split up into at least two partial beam bundles. When passing through scanning beam paths, the partial beam bundles undergo different polarization-optical effects. After the differently polarized partial beam bundles are recombined at a combination grating, a plurality of phase-displaced, displacement-dependent scanning signals is able to be generated from the resulting beam bundle. No polarization-optical components are arranged in the scanning beam paths of the partial beam bundles between the splitting and recombination. To generate the different polarization-optical effects on the partial beam bundles, a conically incident illumination beam bundle impinges upon the splitting grating, the incident illumination beam bundle extending in a plane perpendicular to the measuring direction at an angle other than 0°, the plane of incidence being defined by the grating normal to the splitting grating and the direction of incidence of the illumination beam bundle. The scanning beam paths of the partial beam bundles are arranged in mirror symmetry with respect to the plane of incidence between the splitting and recombination.

Various optical systems equipped with diode laser light sources are discussed in the present application. One example system includes a diode laser light source for providing a beam of radiation. The diode laser has a spectral output bandwidth when driven under equilibrium conditions. The system further includes a driver circuit to apply a pulse of drive current to the diode laser. The pulse causes a variation in the output wavelength of the diode laser during the pulse such that the spectral output bandwidth is at least two times larger than the spectral output bandwidth under the equilibrium conditions.