A first light source outputs measurement light having a wavelength in infrared range. A second light source outputs guide light having a wavelength in visible range. A fiber coupler includes a first port into which the measurement light is input, a second port into which the guide light is input, and a third port outputting combined light formed by combining the measurement light and the guide light with each other. A measurement unit emits the combined light to a measurement object and receives return light reflected therefrom. A processing unit obtains information relating to a distance, a speed, or an oscillation of the measurement object, based on an interference signal of the return light and the reference light. The fiber coupler is formed by a single mode fiber that has a cutoff wavelength that is shorter than that of the measurement light and longer than that of the guide light.

A first light source outputs measurement light having a wavelength in infrared range. A second light source outputs guide light having a wavelength in visible range. A fiber coupler includes a first port into which the measurement light is input, a second port into which the guide light is input, and a third port outputting combined light formed by combining the measurement light and the guide light with each other. A measurement unit emits the combined light to a measurement object and receives return light reflected therefrom. A processing unit obtains information relating to a distance, a speed, or an oscillation of the measurement object, based on an interference signal of the return light and the reference light. The fiber coupler is formed by a single mode fiber that has a cutoff wavelength that is shorter than that of the measurement light and longer than that of the guide light.

A method of assessing tissue health comprises the steps of obtaining depth-resolved spectra of a selected area of in vivo tissue, and assessing the health of the selected area based on the depth-resolved structural information of the scatterers. Obtaining depth-resolved spectra of the selected area comprises directing a sample beam towards the selected area at an angle, and receiving an angle-resolved scattered sample beam. The angle-resolved scattered sample beam is cross-correlated with the reference beam to produce an angle-resolved cross-correlated signal about the selected area, which is spectrally dispersed to yield an angle-resolved, spectrally-resolved cross-correlation profile having depth-resolved information about the selected area. The angle-resolved, spectrally-resolved cross-correlation profile is processed to obtain depth-resolved information about scatterers in the selected area.

A method for measuring a surface of an object including at least one structure using low coherence optical interferometry, the method including the steps of acquiring an interferometric signal at a plurality of measurement points in a field of view and, for at least one measurement point, attributing the interferometric signal acquired to a class of interferometric signals from a plurality of classes, each of the classes being associated with a reference interferometric signal representative of a typical structure; and analysing the interferometric signal to derive therefrom an item of information on the structure at the measurement point, as a function of its class.

A method for measuring a surface of an object including at least one structure using low coherence optical interferometry, the method including the steps of acquiring an interferometric signal at a plurality of measurement points in a field of view and, for at least one measurement point, attributing the interferometric signal acquired to a class of interferometric signals from a plurality of classes, each of the classes being associated with a reference interferometric signal representative of a typical structure; and analysing the interferometric signal to derive therefrom an item of information on the structure at the measurement point, as a function of its class.

Embodiments of systems and methods for measuring a surface topography of a semiconductor chip are disclosed. In an example, a method for measuring a surface topography of a semiconductor chip is disclosed. A plurality of interference signals and a plurality of spectrum signals are received by at least one processor. Each of the interference signals and spectrum signals corresponds to a respective one of a plurality of positions on a surface of the semiconductor chip. The spectrum signals are classified by the at least one processor into a plurality of categories using a model. Each of the categories corresponds to a region having a same material on the surface of the semiconductor chip. A surface height offset between a surface baseline and at least one of the categories is determined by the at least one processor based, at least in part, on a calibration signal associated with the region corresponding to the at least one of the categories. The surface topography of the semiconductor chip is characterized by the at least one processor based, at least in part, on the surface height offset and the interference signals.

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 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 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.