An apparatus can comprise an illumination source and at least one wave front sensor that positioned in a first region. A reflector can be positioned in a second region. A measurement plane can be positioned between the first region and the second region. The reflector can be configured to reflect the light. The at least one wave front sensor can be configured to detect the light. Methods of measuring a feature of a glass-based substrate can comprise emitting light from the illumination source. Methods can comprise transmitting the light through a thickness of the glass-based substrate. Method can comprise transmitting the light through a target location of a first major surface of the glass-based substrate. Methods can comprise detecting the light with the at least one wave front sensor and generating a signal based on the detected light.

An apparatus can comprise an illumination source and at least one wave front sensor that positioned in a first region. A reflector can be positioned in a second region. A measurement plane can be positioned between the first region and the second region. The reflector can be configured to reflect the light. The at least one wave front sensor can be configured to detect the light. Methods of measuring a feature of a glass-based substrate can comprise emitting light from the illumination source. Methods can comprise transmitting the light through a thickness of the glass-based substrate. Method can comprise transmitting the light through a target location of a first major surface of the glass-based substrate. Methods can comprise detecting the light with the at least one wave front sensor and generating a signal based on the detected light.

A laser transmission apparatus utilizing multiple laser beams and beam paths with a diverger lens to provide an illumination pattern that can compensate for lateral movement of the platform during shearography is provided. Further, this optical setup requires no moving parts and does not reduce power of the laser beams as they move through the individual components thereof. From the perspective of the surface being scanned or inspected, the present disclosure may provide two laser images of a single surface that appear to be identical despite the fact that they were taken from two different spatial positions of the moving platform.

A laser transmission apparatus utilizing multiple laser beams and beam paths with a diverger lens to provide an illumination pattern that can compensate for lateral movement of the platform during shearography is provided. Further, this optical setup requires no moving parts and does not reduce power of the laser beams as they move through the individual components thereof. From the perspective of the surface being scanned or inspected, the present disclosure may provide two laser images of a single surface that appear to be identical despite the fact that they were taken from two different spatial positions of the moving platform.

A laser transmission assembly for shearography and related systems utilizing transmissive geometric phase plate pairs in place of Risley prism pairs or movable mirrors therein. Transmissive geometric phase plates provide for a system that is more compact than systems utilizing mirrors or Risley prism pairs while maintaining or improving the adjustability of the system and further offering beamshaping to provide desired illumination patterns.

A defect detection apparatus is provided that can inspect a measurement region of a target object at one time and without inconsistencies arising within the measurement region. A defect detection apparatus 10 includes: a generation unit (signal generator 11 and vibrator 12) for generating an elastic wave in a target object S; an illumination unit (pulsed laser light source 13 and illumination light lens 14) for performing stroboscopic illumination onto a measurement region of a surface of the target object S; and a displacement measurement unit (speckle shearing interferometer 15) for collectively measuring displacements in a normal direction at each point of the measurement region with respect to at least three mutually-different phases of the elastic wave by controlling a phase of the elastic wave and a timing of the stroboscopic illumination. Defects in the measurement region are detected based on the displacements in the normal direction at each point of the measurement region with respect to at least three phases that are obtained by the displacement measurement unit.

According to one aspect, the invention relates to a device (100, 200, 300, 400, 500) for measuring the distance, with respect to a reference plane (P.sub.REF), from a point of light (P.sub.i) of an object (O). The device comprises a two-dimensional detector (30) comprising a detection plane (P.sub.DET) and an imaging system (10) adapted to form an image of a light spot (P.sub.i) situated on an object of interest plane (11) in an image plane (11′) arranged in the vicinity of the detection plane (P.sub.DET) or a conjugate plane (P′.sub.DET) of the detection plane. The device further comprises a separator element (20) for forming, from a beam emitted by a point of light of the object of interest plane (11), and emerging from the imaging system (10) at least two coherent beams, having a spatial superposition region in which the beams interfere and a signal processing means (50) for determining, from the interference pattern formed on the detection plane, and resulting from the optical interferences between said coherent beams, the distance from the point of light to a conjugate plane of the detection plane in the object space of the imaging system (10), said conjugate plane of the detection plane forming the reference plane (P.sub.REF).

Described herein is an apparatus for non-destructive testing that includes a cavity. The apparatus also includes an input element coupled with the cavity and configured to receive a laser beam and to direct the laser beam into the cavity. The apparatus additionally includes multiple output elements formed in the cavity and spaced apart along the cavity. Each output element of the multiple output elements is configured to direct a portion of the laser beam out of the cavity such that each portion of the laser beam directed out of a respective one of the multiple output elements has a substantially similar intensity.

Polarization-based coherent gradient-sensing systems and methods for measuring at least one surface-shape property of a specularly reflective surface are disclosed. The method includes: reflecting a first circularly polarized laser beam from a sample surface to form a second circularly polarized laser beam that contains surface-shape information; converting the second circularly polarized laser beam to a linearly polarized reflected laser beam; directing respective first and second portions of the linearly polarized reflected laser beam to first and second relay assemblies that constitute first and second interferometer arms. The first and second relay assemblies each use a pair of axially spaced-apart gratings to generate respective first and second interference patterns at respective first and second image sensors. Respective first and second signals from the first and second image sensors are processed to determine the at least one surface-shape property.

A multiple mirror for multiplying a single incident wavefront of electromagnetic radiation into a plurality of outgoing wavefronts, including at least one first mirror, onto which the incident wavefront first falls, and a second mirror, on which the wavefront is last reflected, wherein the mirror planes are superimposed in the direction of movement of the first wavefront. The first mirror is partially transparent to the electromagnetic radiation and the second mirror is fully reflective.