A method for determining a separation distance between a working head in a machine for laser processing a material and a surface of the material includes generating a measurement beam of low coherence optical radiation, leading the measurement beam towards the material and a reflected or diffused measurement beam towards an optical interferometric sensor arrangement in a first direction of incidence, generating a reference beam of low coherence optical radiation, leading the reference beam towards the optical interferometric sensor arrangement in a second direction of incidence superimposing the measurement and reference beams on a common region of incidence, detecting a position of a pattern of interference fringes between the measurement and reference beams on the common region of incidence, and determining a difference in optical length between the measurement and reference optical paths based on the position of the pattern of interference fringes along an illumination axis.

A method and a system for determining relative position of an element of an optical system of an assembly for processing or measuring an object along a measurement line, involve generating a measurement beam and a reference beam of low coherence optical radiation. The measurement and reference beams, alternately or in combination, have a main beam and a multiplexed additional beam. The measurement beam, led toward the element of the optical system, and back-reflected, is superimposed on the reference beam in a region of common incidence of an interferometric optical sensor arrangement. Position or frequency of a main interference fringe pattern and an additional interference fringe pattern is detected.

A background subtraction method and tilt stage device for eliminating contaminated or spurious interference patterns by reducing retrace errors. An optical reference surface secured in a pivoting mount coupled to a tilt actuator is configured to angularly displace the pivoting mount and optical reference surface. A microcontroller coupled to the tilt actuator controls the tilt displacement of the tilt actuator providing a plurality of wavefront measurements of the reference surface at a plurality of angles to provide a system and method for background measurement.

A method for determining local position of an optical element associated with an optical path for transporting a laser beam in a working head of a machine for laser processing a material, includes generating a measurement beam of low coherence optical radiation traveling a measurement optical path, leading the measurement beam towards the optical element and the reflected or diffused measurement beam towards an optical interferometric sensor arrangement, generating a reference beam of low coherence optical radiation traveling a reference optical path and leading the reference beam towards the interferometric optical sensor arrangement, superimposing the measurement and reference beams on a common region of incidence, detecting a position of a pattern of interference fringes between the measurement and reference beams, and determining a difference in optical length between the measurement and reference optical paths as a function of the position of the interference pattern along an illumination axis, or of the frequency of the interference pattern in the frequency domain.

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.

A focus scan type imaging device for imaging a target object in a sample that induces aberration proposed. The device includes: a light source unit for emitting a beam; an optical interferometer for splitting the beam emitted from the light source into a sample wave and a reference wave, and providing an interference wave formed by interference between a reflection wave that is the sample wave reflected from the sample and the reference wave; a camera module for imaging the interference wave; a scanning mirror disposed on an optical path of the sample wave of the optical interferometer and configured to reflect the sample wave to cause the sample wave to scan the sample; a wavefront shaping modulator disposed on the optical path of the sample wave of the optical interferometer; and an imaging controller configured to operate in a phase map calculation mode and in an imaging mode.

A surface profile inspection method and a surface profile inspection system are provided. The surface profile inspection method includes capturing a plurality of interferograms of a surface profile depicting interference between a specimen beam reflected from a surface having the surface profile and a modulated reference beam, wherein each of the plurality of interferograms corresponds to a phase of modulation of the modulated reference beam; extracting pixel values of the plurality of interferograms; calculating phase information of each of the plurality of interferograms based on the extracted pixel values, the phase information of each of the plurality of interferograms related to the phase of modulation of the modulated reference beam at a time the interferogram was captured; and reconstructing the surface profile based on the calculated phase information.

The present invention provides a surface shape measuring device and a surface shape measuring method which do not require a physical reference plane and can improve measurement accuracy without using a mechanical adjustment mechanism. The illumination light condensing point P.sub.Q and the reference light condensing point P.sub.L are arranged as mirror images of each other with respect to the virtual plane VP, and each data of the object light O, being a reflected light of the spherical wave illumination light Q, and the inline spherical wave reference light L is recorded on each hologram. On the virtual plane VP, the reconstructed object light hologram h.sup.V for measurement is generated, and the spherical wave optical hologram s.sup.V representing a spherical wave light emitted from the reference light condensing point P.sub.L is analytically generated. The height distribution of the surface to be measured of the object 4 is obtained from the phase distribution obtained by dividing the reconstructed object light hologram h.sup.V by the spherical wave light hologram s.sup.V. High-accuracy surface shape measurement without requiring a reference plane such as a glass substrate is realized by comparing the phase data of the reflected light acquired from the surface to be measured and the phase distribution on the plane cut surface of the spherical wave obtained analytically.

The invention relates to a free-beam interferometric method for illuminating a sequence of sectional areas in the interior of the light-scattering object. The method makes it possible for the user to select a larger image field and/or a higher image resolution than previously possible with the occurrence of self-interference of the specimen light from a scattering specimen.

The illumination light condensing point P.sub.Q and the reference light condensing point P.sub.L are arranged as mirror images of each other with respect to the virtual plane VP, and each data of the object light O, being a reflected light of the spherical wave illumination light Q, and the inline spherical wave reference light L is recorded on each hologram. On the virtual plane VP, the reconstructed object light hologram h.sup.V for measurement is generated, and the spherical wave optical hologram s.sup.V representing a spherical wave light emitted from the reference light condensing point P.sub.L is analytically generated. The height distribution of the surface to be measured of the object 4 is obtained from the phase distribution obtained by dividing the reconstructed object light hologram h.sup.V by the spherical wave light hologram s.sup.V.