Disclosed are a depth data measuring device and a structured light projection unit included therein. The device comprises: a projection unit, configured to project structured light to the subject; an imaging unit, configured to photograph the subject to obtain a two-dimensional image frame illuminated by the structured light, wherein, the projection unit comprises: a laser generator configured to generate laser light; an LCOS (Liquid Crystal on Silicon) element configured to receive the laser light and generate the structured light for projection. The present disclosure uses LCOS for fine projection of structured light in order to improve imaging accuracy of depth data. LCOS can also transform various projection codes including speckles or stripes, so that it is suitable for various imaging scenarios. Furthermore, the VCSEL structure can be combined to achieve low power consumption and miniaturization of the projection unit, and multiple groups of coaxial photosensitive units can be introduced to reduce the imaging time required for multi-frame merging to calculate depth data and thereby increase the frame rate.

An optical device includes an array of light-emitting elements, including a first subset of light-emitting elements and a second subset of light-emitting elements. The first subset of light-emitting elements is configured to emit light having wavelength L.sub.1. The device includes a high refractive index material selectively disposed on the second subset of light-emitting elements and an array of optical elements positioned so as to be illuminated by the first subset of light-emitting elements and by the second subset of light-emitting elements. The optical elements are regularly arranged in a common plane at a pitch P, the common plane is located a distance D from the array of light-emitting elements, and P.sup.2≈2L.sub.1D/N, N being an integer greater than or equal to 1.

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 system for structured light depth computation using single photon avalanche diodes (SPADs) is configurable to, over a frame capture time period, selectively activate the illuminator to perform interleaved structured light illumination operations. The interleaved structured light illumination operations comprise alternately emitting at least a first structured light pattern from the illuminator and emitting at least a second structured light pattern from the illuminator. The system is also configurable to, over the frame capture time period, perform a plurality of sequential shutter operations to configure each SPAD pixel of the SPAD array to enable photon detection. The plurality of sequential shutter operations generates, for each SPAD pixel of the SPAD array, a plurality of binary counts indicating whether a photon was detected during each of the plurality of sequential shutter operations.

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.

3D metrology techniques are disclosed for determining a changing topography of a substrate processed in an additive manufacturing system. Techniques include fringe scanning, simultaneous fringe projections, interferometry, and x-ray imaging. The techniques can be applied to 3D printing systems to enable rapid topographical measurements of a 3D printer powder bed, or other rapidly moving, nearly continuous surface to be tested. The techniques act in parallel to the system being measured to provide information about system operation and the topography of the product being processed. A tool is provided for achieving higher precision, increasing throughput, and reducing the cost of operation through early detection and diagnosis of operating problems and printing defects. These techniques work well with any powder bed 3D printing system, providing real-time metrology of the powder bed, the most recently printed layer, or both without reducing throughput.

A method for controlling an electronic instrument including a projection section that projects an image via a projection lens and an imaging section that performs imaging via an imaging lens includes causing a first storage to store first characteristic data representing the characteristics of the projection lens, second characteristic data representing the characteristics of the imaging lens, and arrangement data representing the arrangement of the projection lens and the imaging lens and then causing the projection section to project a pattern image on an object via the projection lens, causing the imaging section to capture an image of the pattern image on the object via the imaging lens to generate captured image data, and updating the arrangement data based on the captured image data, the first characteristic data, and the second characteristic data without updating the first characteristic data and the second characteristic data.

Disclosed is a phase-shifting phase measurement error correction method based on pixel tracing of object raster images. During traditional phase-shifting shape measurement, surface height information is represented by phase information. The nonlinearity of equipment inevitably causes errors of phase information calculated according to images captured by a camera. The method comprises: projecting, by projector, a special raster projection to resolve a pixel-tracing mapping relation; in a direction against a light path, determining the position of a point light source that illuminates any one image pixel in a captured image and is located in an imaging plane of the projector according to the pixel-tracing mapping relation; and finally, replacing distributed phase information in image pixels with ideal phases in point light sources to correct phase errors to improve the accuracy of phase-shifting shape measurement. Compared with existing methods, the method is easy to operate and high in efficiency and precision.

A measurement apparatus, comprising: a projection apparatus configured to project a predetermined pattern on a subject; and an image capturing system configured to capture a group of images from at least two different viewpoints, wherein the distance between the viewpoints is shorter than the distances between the projection apparatus and the viewpoints, the measurement apparatus further comprising: relative position calculation means for obtaining a relative position of the projection apparatus relative to at least one of the viewpoints from pattern image positions on the group of images and a positional relationship between the viewpoints, wherein distance information regarding the subject is acquired from the relative position and a pattern image position on an image at the viewpoint.

Disclosed are a 3D scanner, an additive manufacturing system and an apparatus and method for identifying features of a 3D object manufactured in such a system. An apparatus comprises an optical projection assembly comprising a light source and an optical grating, for illuminating an object with first and second light patterns having different spatial frequencies, wherein the optical projection assembly provides a first light pattern in a first configuration of the optical projection assembly and provides a second light pattern in a second configuration of the optical projection assembly. An image capturing apparatus is used to capture images corresponding to reflections of the first and second light patterns from the illuminated object, and a processing unit is used to identify, from the captured reflections of the first and second light patterns, the effects of distortions in the reflected light patterns corresponding to features of the illuminated object.