Aspects of the subject disclosure are directed towards safely projecting a diffracted light pattern, such as in an infrared laser-based projection/illumination system. Non-diffracted (zero-order) light is refracted once to diffuse (defocus) the non-diffracted light to an eye safe level. Diffracted (non-zero-order) light is aberrated twice, e.g., once as part of diffraction by a diffracting optical element encoded with a Fresnel lens (which does not aberrate the non-diffracted light), and another time to cancel out the other aberration; the two aberrations may occur in either order. Various alternatives include upstream and downstream positioning of the diffracting optical element relative to a refractive optical element, and/or refraction via positive and negative lenses.

An estimation method includes projecting a pattern image onto an object via a zoom lens, generating imaging data by capturing the pattern image on the object, estimating, based on the imaging data, a position of a principal point of the zoom lens during the projection of the pattern image, and estimating, based on a first characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in a first position and a second characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in a second position, a characteristic value representing a characteristic of the zoom lens at time when the principal point of the zoom lens is present in the estimated position.

A calibration method for fringe projection systems based on plane mirrors. Firstly, two mirrors are placed behind the tested object. Through the reflection of mirrors, the camera can image the measured object from the front and other two perspectives, so as to obtain 360-degree two-dimensional information of the measured object. The projector projects three sets of phase-shifting fringe patterns with frequencies of 1, 8, and 64. The camera captures the fringe image to obtain an absolute phase map with a frequency of 64 by using the phase-shifting method and the temporal phase unwrapping algorithm. By using the calibration parameters between the projector and the camera, the absolute phase map can be converted into three-dimensional information of the measured object. Then, the mirror calibration is realized by capturing a set of 3D feature point pairs, so that the 3D information from different perspectives is transformed into a unified world coordinate system. The calibration method does not need to artificially fix the feature pattern on plane mirrors, only needs to capture a set of 3D feature point pairs by the camera to directly realize the mirror calibration that it avoids the loss of measurement accuracy and realizes high-precision panoramic three-dimensional measurement.

A fracture surface inspection device for inspecting a first fracture surface and a second fracture surface that are generated through fracture splitting, which is provided with a data acquisition unit configured to acquire two-dimensional data and three-dimensional data on each of the fracture surfaces, a contour extraction unit configured to extract, from the two-dimensional data, a first contour of the first fracture surface and a second contour of the second fracture surface, a transformation amount calculation unit configured to calculate a transformation amount X(affine) when the second contour is affine-transformed to the first contour, a distortion correction unit configured to calculate distortion correction data by affine-transforming the three-dimensional data on the second fracture surface with the transformation amount X(affine), and a comparison unit configured to compare the three-dimensional data on the first fracture surface and the distortion correction data.

The present disclosure provides a phase unwrapping method based on multi-view constraints of a light field and related components. The method includes: sampling main view phases at different depths in a measurement scene; performing polynomial calibration on a mapping relation from the main view phase to the pixel coordinates of the corresponding points in auxiliary view images; calculating a candidate absolute phase set of each pixel in a main view image; traversing the candidate absolute phase set, calculating an error value between the candidate absolute phase set and wrapped phases of the pixel coordinates of the corresponding points in all the auxiliary view images by utilizing a calibrated mapping relation, and taking a candidate phase corresponding to the minimum error value as an absolute phase of each pixel in the main view image. The present disclosure can stably realize accurate phase unwrapping of the structured light field.

The present disclosure proposes a detachable second apparatus coupled to a first apparatus that determines a first three-dimensional shape of an object and configured to determine an angle of an upper surface of the object. The second apparatus includes a first light source configured to sequentially irradiate first pattern lights having one phase range, a beam splitter and lenses configured to change optical paths of the first pattern lights so that a beam of light corresponding to a respective phase of the phase range spreads, and arrives at each point of a partial region of the upper surface of the object, a communication interface, and a first processor configured to obtain first information on first reflected lights generated by reflecting the first pattern lights from the partial region and determine the angle of the upper surface with respect to the reference plane based on the first information.

A shape measuring apparatus applies, to a light beam, a periodic pattern having periodicity in a direction perpendicular to an optical axis and displaceable in the direction perpendicular to the optical axis, relatively displaces a focal point of an objective lens in a direction parallel to the optical axis, and calculates, based on amplitude of intensity of the light beam detected by a photodetector, face shape data on the object to be measured. Then, a top surface measuring step of acquiring face shape data on a top surface of the object to be measured, and a bottom surface measuring step of acquiring face shape data on a bottom surface of the object to be measured by transmitting through the top surface of the object to be measured and aligning the focal point of the objective lens on the bottom surface of the object to be measured are performed.

The present disclosure proposes an apparatus for determining a first three-dimensional shape of an object. The apparatus includes one or more first light sources configured to irradiate one or more first pattern lights to the object, a second light source configured to sequentially irradiate one or more second pattern lights having one phase range, a beam splitter and one or more lenses configured to change optical paths of the one or more second pattern lights, an image sensor configured to capture one or more first reflected lights and one or more second reflected lights, and a processor configured to determine the first three-dimensional shape of the object based on the one or more first reflected lights and the one or more second reflected lights.

A method for registering an imaging detector to a surface projects and records a sequence having a first sparse pattern of lines followed by a second sparse pattern of lines. A first subset of positions receives lines from both first and second sparse patterns corresponding to a first label. A second subset of positions receives only lines from the first sparse pattern corresponding to a second label. A third subset of positions receives only lines from the second sparse pattern corresponding to a third label. The first, second, and third labels are decoded and each member element of the first, second, and third subsets of positions registered to the imaging detector according to the decoded labels. One or more dense patterns of lines positionally correlated with registered member elements of the decoded labels are projected and recorded. An image of the surface contour is formed according to the recorded pattern.

Provided is an inter-reflection detection apparatus including: an irradiation unit configured to emit light having variable-frequency sinusoidal patterns; an image acquisition unit configured to acquire an image of an object irradiated with the light from the irradiation unit; a phase determination unit configured to determine a phase at each position in the image; and a detection unit configured to detect a region in which inter-reflection occurs. The detection unit is configured to determine a phase difference between a phase acquired from an image generated by irradiation of a low-frequency sinusoidal pattern and a phase acquired from an image generated by irradiation of a high-frequency sinusoidal pattern for a plurality of combinations of low-frequency waves and high-frequency waves, and determine that inter-reflection occurs in a region in which the phase difference for any one of the plurality of combinations is equal or more than a threshold.