Fiducial patterns that produce 2D Barker code-like diffraction patterns at a camera sensor are etched or otherwise provided on a cover glass in front of a camera. 2D Barker code kernels, when cross-correlated with the diffraction patterns captured in images by the camera, provide sharp cross-correlation peaks. Misalignment of the cover glass with respect to the camera can be derived by detecting shifts in the location of the detected peaks with respect to calibrated locations. Devices that include multiple cameras behind a cover glass with one or more fiducials on the cover glass in front of each camera are also described. The diffraction patterns caused by the fiducials at the various cameras may be analyzed to detect movement or distortion of the cover glass in multiple degrees of freedom.

An embodiment relates to a light source module dynamically controlling a phase distribution of light. The light source module includes a semiconductor stack portion. The semiconductor stack portion includes a stacked body including an active layer and a photonic crystal layer causing Γ-point oscillation, and includes a phase synchronization portion and an intensity modulation portion which are arranged in a Y-direction as one resonance direction of the photonic crystal layer. The stacked body in the intensity modulation portion has M (≥2) pixels each arranged in an X-direction and including N.sub.1 (≥2) subpixels. A length of a region including consecutive N.sub.2 (≥2, ≤N.sub.1) subpixels among the N.sub.1 subpixels, defined in the X-direction, is smaller than an emission wavelength of the active layer. The light source module outputs laser light from each M pixel included in the intensity modulation portion in a direction intersecting both X- and Y-directions.

A method for compensating beam angle variation of a beam bundle of laser beams with respective beam angles includes generating the beam bundle using a diffractive optical element, determining a beam angle value from a beam angle of at least one laser beam of a first subset of the laser beams, detecting a light pattern projected by a second subset of the laser beams, and evaluating the light pattern. The evaluation is performed taking into account the beam angle variation of the beam angles of the second subset of the laser beams on the basis of the determined beam angle value.

A device for machining material by means of laser radiation, including a focusing optics for focusing a laser beam onto a workpiece and an adjusting optics for adjusting the intensity distribution comprising at least two plate-shaped optical elements which are arranged one behind the other in the beam path of the laser beam, which are rotatable relative to one another in the circumferential direction, and which each have a surface with a circular pattern of sector-shaped facets which, in the circumferential direction, are alternately inclined with respect to the respective plate plane.

A measurement device for a linear stage includes a two-dimensional grating and a measurement unit respectively disposed on first and second moving stages of the linear stage. The measurement unit includes a light source, a two-dimensional sensor and a processor. The light source emits incident light to the two-dimensional grating so that the incident light is reflected thereby to result in reflection light. The two-dimensional sensor receives the reflection light and converts the same to a reflection signal. The processor receives the reflection signal and determines accordingly a first rotational angle, and first and second displacement components of a displacement of the first moving stage.

A method for assessing the relative alignment of a first and second diffractive element. The method includes illuminating the first diffractive element to form a first diffraction pattern in the far field and illuminating the second diffractive element to form a second diffraction pattern in the far field. The method further comprises determining a positional and/or rotational relationship between the first diffraction pattern and the second diffraction pattern in the far field.

A wearable display system with a limited number of cameras. Two cameras can be arranged to provide an overlapping central view field and a peripheral view field associated with one of the two cameras. A third camera can be arranged to provide a color view field overlapping the central view field. The wearable display system may be coupled to a processor configured to generate a world model and track hand motion in the central view field using the two cameras. The processor may be configured to perform a calibration routine to compensate for distortions during use of the wearable display system. The processor may be configured to identify and address portions of the world model including incomplete depth information by obtaining additional depth information, such as by enabling emitters, detecting planar surfaces in the physical world, or identifying relevant object templates in the world model.

An index grating of an optical encoder provided by the invention has a main technical feature of increasing a ratio of light-transmissible area of a grating per unit area, thereby increasing a light source utilization efficiency and a signal intensity, and reducing light-blocking ratio caused by dust and other foreign matters, thereby reducing a degree of influence on light intensity, so as to improve a sensing precision of the optical encoder.

Metrology methods, systems and targets are provided, which implement a side by side paradigm. Adjacent cells with periodic structures are used to extract the overlay error, e.g., by introducing controllable phase shifts or image shifts which enable algorithmic computation of the overlay. The periodic structures are designed to exhibit a rotational symmetry to support the computation and reduce errors.

In various embodiments, alignment systems for laser resonators generate near-field and/or far-field images of input beams produced by the laser resonators to enable the alignment of the input beams.