A holographic observation method includes: casting a light beam generated by driving a semiconductor laser light source with an electric current with an alternating-current component superimposed or a light beam having a predetermined spectral width and predetermined spectral intensity to have predetermined coherency to an observation object; forming a hologram by causing a light beam transmitted through or reflected by the observation object to interfere with a reference light beam; and obtaining information on the observation object by performing image processing on the hologram.

A method for defect inspection of a transparent substrate comprises utilizing a wavefront reconstruction unit to obtain complex defect diffraction wavefront of a transparent substrate; using a complex defect diffraction module to confirm the effective diffraction distance of the complex defect diffraction wavefront; utilizing a defect detection module to detect position of the defect of the transparent substrate; using a defect classification module to perform extraction, analysis and classification of diffraction characteristics and utilizing a machine learning algorithm or a deep learning algorithm to automatically identify the defects.

Light reflected from an illuminated object is mixed with a reference beam and sensed at a sensor array of a digital hologram apparatus. Digital hologram data, determined from the sensed light, is dependent upon complex valued reflection coefficients of the object and upon phase perturbations in propagation paths between the object and the sensor array. Reflectance values, which may be dependent upon expected values of the absolute square of the reflection coefficients, and phase perturbations are determined for which a test function is at an extremum, where the test function contains a data fidelity term dependent upon the hologram data from a single hologram, a first regularization term dependent upon the phase perturbations and a second regularization term dependent upon the reflectance values. An image of the object may be formed from the reflectance values and a wavefront of the reflected light may be determined from the phase perturbations.

Example embodiments relate to an integrated lens-free imaging device. One embodiment includes a lens-free imaging device for imaging a sample. The lens-free imaging device includes a radiation guiding structure that includes a first surface parallel with a second surface. The lens-free imaging device also includes an imaging region. The radiation guiding structure is adapted for receiving an incoming radiation wave, thereby obtaining a confined radiation wave. At least one perturbation is present in the radiation guiding structure for generating, from the confined radiation wave, a first radiation wave and a second radiation wave. The radiation guiding structure is configured to direct the first radiation wave out of the radiation guiding structure toward the first surface to a sample measurement region. The radiation guiding structure is further configured to direct the second radiation wave toward the second surface to the imaging region.

Disclosed is a method and associated apparatus for measuring a characteristic of interest relating to a structure on a substrate. The method comprises calculating a value for the characteristic of interest directly from the effect of the characteristic of interest on at least the phase of illuminating radiation when scattered by the structure, subsequent to illuminating said structure with said illuminating radiation.

A method of correcting a holographic image, a processing device, a dark field digital holographic microscope, a metrology apparatus and an inspection apparatus. The method includes obtaining a holographic image; determining at least one attenuation function due to motion blur from the holographic image; and correcting the holographic image, or a portion thereof, using the at least one attenuation function.

Systems and methods for recording holographic gratings in accordance with various embodiments of the invention are illustrated. One embodiment includes a holographic recording system including a first movable platform configured to support a first plurality of waveguide cells for exposure, at least one master grating, and at least one laser source configured to provide a set of recording beams by directing light towards the at least one master grating, wherein the first movable platform is translatable in predefined steps along at least one of two orthogonal directions, and wherein at each the predefined step at least one waveguide cell is positioned to be illuminated by at least one recording beam within the set of recording beams.

The invention relates to a device, such as a digital holographic microscope (1), for detecting and processing a first full image of a measurement object, measured with a first offset, wherein an arrangement is provided for generating at least one further full image with at least one offset that differs from said first offset.

When the optical system is illuminated with an illumination light flux emitted from one extant input image point, an interference image generated by superimposing an extant output light flux output from the optical system and a reference light flux coherent with the extant output light flux is imaged to acquire interference image data, and thus to acquire measured phase distribution, and this acquisition operation is applied to each extant input image point. Thus, each measured phase distribution is expanded by expanding functions n(u, v) having coordinates (u, v) on a phase defining plane as a variable to be represented as a sum with coefficients n{Ajn.Math.n(u, v)}. When the optical system is illuminated with a virtual illumination light flux, a phase (u, v) of a virtual output light flux is determined by performing interpolation calculation based on coordinates of a virtual light emitting point.

Laser 3D imaging techniques include splitting a laser temporally-modulated waveform of bandwidth B and duration D from a laser source into a reference beam and a target beam and directing the target beam onto a target. First data is collected, which indicates amplitude and phase of light relative to the reference beam received at each of a plurality of different times during a duration D at each optical detector of an array of one or more optical detectors perpendicular to the target beam. Steps are repeated for multiple sampling conditions, and the first data for the multiple sampling conditions are synthesized to form one or more synthesized sets. A 3D Fourier transform of each synthesized set forms a digital model of the target for each synthesized set with a down-range resolution based on the bandwidth B.