An optical measurement apparatus includes a light source unit generating and outputting light, a polarized light generating unit generating polarized light from the light, an optical system generating a pupil image of a measurement target, using the polarized light, a self-interference generating unit generating multiple beams that are split from the pupil image, and a detecting unit detecting a self-interference image generated by interference of the multiple beams with each other.

Method for simultaneously compensating pupil coordinate distortion and shear amount change in a process of wavefront reconstruction in grating transverse shear interference. Where a wavefront is diffracted by a grating, the shapes and light paths of the diffracted wavefronts of all the orders are different, so that on one hand, a coordinate system detected by a detector plane is distorted relative to a pupil coordinate system, and on the other hand, a shear amount changes along with a coordinate position.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.

Various methods, systems and apparatus are provided for imaging and sensing using interferometry. In one example, a system includes an interferometer; a light source that can provide light to the interferometer at multiple wavelengths (λ.sub.i); and optical path delay (OPD) modifying optics that can enhance contrast in an interferometer output associated with a sample. The light can be directed to the sample by optics of the interferometer. The interferometer output can be captured by a detector (e.g., a camera) at each of the multiple wavelengths (λ.sub.i). In another example, an apparatus includes an add-on unit containing OPD that can enhance contrast in an interferometer output associated with a sample illuminated by light at a defined wavelength (λ.sub.i). A detector can be attached to the add-on unit to record the interferometer output at the defined wavelength (λ.sub.i).

Various methods, systems and apparatus are provided for imaging and sensing using interferometry. In one example, a system includes an interferometer; a light source that can provide light to the interferometer at multiple wavelengths (λ.sub.i); and optical path delay (OPD) modifying optics that can enhance contrast in an interferometer output associated with a sample. The light can be directed to the sample by optics of the interferometer. The interferometer output can be captured by a detector (e.g., a camera) at each of the multiple wavelengths (λ.sub.i). In another example, an apparatus includes an add-on unit containing OPD that can enhance contrast in an interferometer output associated with a sample illuminated by light at a defined wavelength (λ.sub.i). A detector can be attached to the add-on unit to record the interferometer output at the defined wavelength (λ.sub.i).

A defect inspection device (100) includes an excitation unit that excites an elastic wave, an irradiation unit (2) that applies laser lights, a measurement unit (3) that measures the interfered laser lights, and a control unit that acquires vibration state information which is information about a state of the elastic wave excited in an inspection target (P) for a plurality of frequencies by changing a frequency of excitation vibration caused by the excitation unit in order to excite the elastic wave in the inspection target (P), and extracts recommended frequencies (F) recommended for inspecting a defect of the inspection target (P) from among the plurality of frequencies based on the acquired vibration state information for the plurality of frequencies.

A defect inspection device (100) includes an excitation unit that excites an elastic wave, an irradiation unit (2) that applies laser lights, a measurement unit (3) that measures the interfered laser lights, and a control unit that acquires vibration state information which is information about a state of the elastic wave excited in an inspection target (P) for a plurality of frequencies by changing a frequency of excitation vibration caused by the excitation unit in order to excite the elastic wave in the inspection target (P), and extracts recommended frequencies (F) recommended for inspecting a defect of the inspection target (P) from among the plurality of frequencies based on the acquired vibration state information for the plurality of frequencies.