An optical metrology device, such as an interferometer, detects sub-resolution defects on a sample, i.e., defects that are smaller than a pixel in the detector array of the interferometer. The optical metrology device obtains optical metrology data at each pixel in at least one detector array and determines parameter values of a signal model for a pixel of interest using the optical metrology data received by a plurality of pixels neighboring a pixel of interest. A residual for the pixel of interest is determined using the optical metrology data received by the pixel of interest and determined parameter values for the signal model for the pixel of interest. A defect, which may be smaller than the pixel of interest can then be detected based on the residual for the pixel of interest.

The present invention relayes to a method and an assembly for chromatic confocal spectral interferometery, in particular also for spectral domain OCT (SD-OCT) using multi-spectral light. A multiple (e.g. two, three, four, etc.) axial splitting of foci in the interferometric object arm is performed using a multifocal (e.g. bifocal, trifocal, quattro-focal, etc.) optical component, forming thereby at least two, three or even several groups of chromatically split foci in the depth direction. The multifocal optical component is made of a diffractive optical element (712) and a Schwarzschild objective (5). At least two, three, four or even more differently colored foci of different groups of foci coincide in at least one confocal point in the object space of the setup. Thus, at least two, three or even more spectral wavelets are formed in the case of optical scanning of an object measurement point and spectral detection in the wavenumber domain, which wavelets are at least slightly spectrally separated from each other. This results in a significant increase in the optical primary data in the wavenumber domain and reduces the trade-off of the chromatic confocal spectral interferometry between axial measurement range and depth resolution. From the detected data, it is possible to calculate tan (alpha) as the quotient of the absolute phase shift delta_phi and the associated wavenumber difference delta_k, the Fourier transform over the spectral data, in order to respectively determine the optical path difference.

An interferometer uses a phase shift mask that includes an array of pixels that are aligned with a corresponding array of pixels of a detector. Each pixel in the phase shift mask is adapted to produce one of a number of predetermined phase shifts between a test beam and a reference beam. For example, the pixels may be linear polarizers or phase delay elements having one of the number of polarizer orientations or phase delays to produce the predetermined phase shifts between the test beam and the reference beam. The pixels in the phase shift mask are arranged in the array to include each of the predetermined phase shifts in repeating pixel groups in rows that are one column wide, columns that are one row high, or blocks of multiple rows and columns.

Methods and systems for focusing and measuring by mean of an interferometer device, having an optical coherence tomography (OCT) focusing system, by separately directing an overlapped measurement and reference wavefront towards a focus sensor and towards an imaging sensor; where a predefined focusing illumination spectrum of the overlapped wavefront is directed towards the focus sensor, and where a predefined measurement illumination spectrum of the overlapped wavefront is directed towards the imaging sensor. Methods and systems for maintaining focus of an interferometer device, having an OCT focusing system, during sample's stage moves.

Provided is a device for measuring a lens three-dimensional profile based on laser wavenumber scanning, including: a semiconductor laser for emitting coherent light; a beam splitter for dividing the coherent light into two parts; an optical wedge; a CCD camera for capturing an interference image; a computer for processing image information; a laser controller for adjusting an operating temperature and an operating current of the semiconductor laser; and a bilateral telecentric lens. The coherent light is reflected by the optical wedge and then reaches the bilateral telecentric lens through the beam splitter, to form a first reflected light path. The coherent light is reflected by the measured lens, and then reaches the bilateral telecentric lens through the beam splitter, to form a second reflected light path. The first reflected light path and the second reflected light path form an interference image after passing through the bilateral telecentric lens.

A sample shape measuring method includes a step of preparing illumination light passing through a predetermined illumination region, a step of applying the illumination light to a sample, and a predetermined processing step. The predetermined illumination region is set so as to include an optical axis at a pupil position of an illumination optical system. Light transmitted through the sample is incident on the observation optical system. The predetermined processing step includes a step of receiving light emerged from the observation optical system, a step of obtaining a quantity of light of the received light, a step of calculating a difference or a ratio between the quantity of light and a reference quantity of light, and a step of calculating an amount of tilt in a surface of the sample from the difference or the ratio.

Methods and systems for focusing and measuring by mean of an interferometer device, having an optical coherence tomography (OCT) focusing system, by separately directing an overlapped measurement and reference wavefront towards a focus sensor and towards an imaging sensor; where a predefined focusing illumination spectrum of the overlapped wavefront is directed towards the focus sensor, and where a predefined measurement illumination spectrum of the overlapped wavefront is directed towards the imaging sensor. Methods and systems for maintaining focus of an interferometer device, having an OCT focusing system, during sample's stage moves.

A system of super-resolution full-field optical metrology for delivering information on the surface topography of a sample or object on the far-field nanometre scale, including a light source, an interferometer (1a, 1b, 1c, 1d) including a reference arm incorporating a micro bead and a mirror, an object arm including a micro bead similar to the micro bead and arranged in immediate proximity to the surface of the object, receiving structure for capturing the interference figures, and a processor for processing these interference figures in such a way as to produce surface topography information. The light source is temporally coherent or partially coherent. The interferometer and the processor for processing interference figures are designed to reconstruct the surface of the object by phase shifting interferometry.

An interferometer uses a phase shift mask that includes an array of pixels that are aligned with a corresponding array of pixels of a detector. Each pixel in the phase shift mask is adapted to produce one of a number of predetermined phase shifts between a test beam and a reference beam. For example, the pixels may be linear polarizers or phase delay elements having one of the number of polarizer orientations or phase delays to produce the predetermined phase shifts between the test beam and the reference beam. The pixels in the phase shift mask are arranged in the array to include each of the predetermined phase shifts in repeating pixel groups in rows that are one column wide, columns that are one row high, or blocks of multiple rows and columns.

An optical coherence tomograph includes a wavelength tunable illuminating device, an illumination and measurement beam path with a dividing element and a scanner and a front optical unit and a reference beam path, a detection beam path and a flat panel detector. A beam splitter conducts the separated measurement radiation to the detection beam path and an optical element acts only on the illumination radiation. The optical element sets the numerical aperture of the illumination of the illumination field in the eye. An optical element acts only on the measurement radiation and sets the numerical aperture with which measurement radiation is collected in the eye. An aperture is arranged in front of the flat panel detector in an intermediate image plane and defines the size of an object field. The flat panel detector has a spatial resolution of 4 to 100 pixels in a direction.