A motion compensation system for a shearography apparatus includes: an adjustable first fold mirror to reflect laser radiation to a receiving aperture of the shearography apparatus during separate pulse periods at corresponding angles of reflection; and corresponding second fold mirrors to reflect the laser radiation from a target surface to the first fold mirror during the respective pulse periods. The shearography apparatus moves with respect to the target surface between the separate pulse periods. The angles of reflection make the laser radiation reflected from the target surface via the respective second fold mirrors appear to the receiving aperture as if the shearography apparatus is stationary with respect to the target surface. In another system, the second fold mirrors are replaced by an adjustable second fold mirror to reflect the laser radiation from the target surface to the first fold mirror during the pulse periods at corresponding second angles of reflection.

An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.

An apparatus for determining a topological charge of one of more optical beams. For single beams, a trapezoidal optical element having a front face and an opposing rear face that is not parallel to the front face is oriented so that the optical beam is reflected in a direction other than along the optical path. The reflection of the optical beam by the trapezoidal optical element produces an interference pattern that can be captured by an optical imager and that can be decoded to determine the topological charge of the optical beam. For a plurality of superpositioned beams, an air spaced trapezoidal optical element may oriented to reflect the plurality of beams onto an optical imager to capture the interference pattern. The interference pattern may be interpreted to identify the topological charge of each of the plurality of optical beams.

The present invention relates to a method comprising reception of an incident electromagnetic wave (9) by a diffractive element (2) and conversion of this incident electromagnetic wave (9) into a diffracted electromagnetic wave (10) by the diffractive element (2); reception of the diffracted electromagnetic wave (10) by a matrix-array sensor (4) comprising a matrix-array of pixels that are aligned along one or two axes of pixel alignment (13, 14). The method comprises a plurality of acquisitions, by the matrix-array sensor (4), of a signal of the diffracted electromagnetic wave (10) corresponding to a plurality of relative positions between the diffractive element (2) and the matrix-array sensor (4). The invention also relates to a device (1) implementing this method.

A wavefront sensor includes a mask and a sensor utilized to capture a diffraction pattern generated by light incident to the mask. A reference image is captured in response to a plane wavefront incident on the mask, and another measurement image is captured in response to a distorted wavefront incident on the mask. The distorted wavefront is reconstructed based on differences between the reference image and the measurement image.

A wavefront measuring device and method obtain wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.

The imaging quality of an optical imaging system is interferometrically measured. A wavefront measurement has a first imaging scale .sub.1 in a first direction and a second imaging scale .sub.2 in a second, perpendicular direction. The second imaging scale differs from the first imaging scale by a scale ratio (.sub.1/.sub.2)1 (anamorphic imaging system). A first measurement structure (MS1) on a first structure carrier arranged on the object side of the imaging system has a two-dimensional mask structure suitable for shaping the coherence of measurement radiation. A second measurement structure (MS2) on a second structure carrier arranged on the image side of the imaging system has a diffraction grating. The first and second measurement structures are mutually adapted, taking account of the scale ratio so that an interference pattern arises upon imaging the first measurement structure onto the second measurement structure using the anamorphic imaging system.

A collimation evaluation device includes a first reflection member, a second reflection member, a screen, and a housing. A first reflection surface of the first reflection member and a first reflection surface of the second reflection member face each other and are parallel to each other. Further, interference fringes are formed on the screen by light L.sub.12 reflected on the first reflection surface of the first reflection member and a second reflection surface of the second reflection member and light L.sub.21 reflected on a second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and collimation of incident light is evaluated on the basis of a direction of the interference fringes.

A shearing interferometer includes first and second shearing plates disposed opposite to each other. The first shearing plate includes a first front surface and a first back surface, and splits an input beam input to the first front surface into first and second beams reflected at the first front and back surfaces, respectively. The second shearing plate includes a second front surface and a second back surface. The second shearing plate splits the first beam into third and fourth beams reflected at the second front and back surfaces, respectively, and splits the second beam into fifth and sixth beams reflected at the second front and back surfaces, respectively. Each of the first and second shearing plates has a thickness which limits a phase delay between the fourth beam and the fifth beam to a degree determined to allow interference to occur between the fourth beam and the fifth beam.

There is provided a wavefront measuring method for obtaining wavefront information of an optical system. The method including: irradiating the optical system with a light beam; allowing the light beam passed via the optical system to come into a diffraction grating having periodicity in a first direction; and obtaining the wavefront information based on an interference fringe formed by light beams generated from the diffraction grating. The diffraction grating including: first portions which allow light to pass therethrough; and second portions which shield light, each of the second portions being provided between two of the first portions. A ratio between a width of one of the first portions in the first direction and a width of one of the second portions in the first direction is changed in the first direction, the one of the first portions and the one of the second portions being adjacent to each other.