A method and sensor system for monitoring in time a geometric property of a gasket (32, 34) that sealingly interconnects two structural members (20, 21) of a subterraneous or immersed tunnel (10). The system includes a sensor (42) for measuring position indications for surface portions (48) of the gasket relative to a reference (26, 27, 47) associated with one or both structural members, and a processor (44) that is coupled with the sensor to receive the position indications. The processor is configured to derive indications of displacement (?Y) for each of the gasket surface portions based on the measured indications of position, to compare the indications of displacement for each of the gasket surface portions with at least one threshold value (Ty), and to generate a warning message for an operator if at least one of the indications of displacement transgresses the at least one threshold value.

A lens meter includes a measurement optical system that projects measurement light to a test lens, and receives the measurement light which has passed through the test lens, a control part that calculates an optical characteristic value of the test lens based on the received measurement light, and controls the measurement optical system, a display part that displays the optical characteristic value by control of the control part, and an imaging part that obtains a lens image of the test lens, wherein the control part generates a mapping image showing distribution of the optical characteristic value of the test lens based on the optical characteristic value and position information of a measurement position of the optical characteristic value, generates a superimposed image in which the mapping image is superimposed onto the lens image, and displays the superimposed image on the display part.

A unique electro optical design will be disclosed, implemented for MTF measurements of multiple optical elements. The measurements are performed over a wide field of view by collimators moving in parallel in a synchronized manner while maintaining accuracy. The movement is angular over a wide angle and in two perpendicular directionspitch and yaw. By design, each said collimator element will perform its angular movement while protecting towards the center of lens under test from remote. Thus, the collimators' center of rotation will be the central point of each lens' input aperture. By shifting a tray loaded with lenses, a different batch will be tested on each sequence. The apparatus is suitable for testing both camera and lenses simultaneously. The apparatus will preferably test lenses or cameras directly on the production floor.

An optical guide has at least two diffraction gratings in serial in front of a light source in order to diffract a light beam from the light source twice. The first diffraction grating could split the light beam into several parallel light beams along a first axis, and the second diffraction grating could split the light beams into several points of light along a second axis, and so on and so forth. By rotating the diffraction gratings relative to one another and by adjusting the distance between the diffraction gratings, a user of the optical guide could adjust the angle of the axis points and adjust a relative distance of the points of light relative to one another. These light beams could provide convenient guides for users in a variety of applications.

A reflectivity test circuit is described. The reflectivity test circuit includes a symmetric structure that cancels errors in the reflectivity measurements. In particular, the reflectivity test circuit includes an optical waveguide that is optically coupled to two optical ports and two optical couplers. The optical couplers are optically coupled to adjacent optical waveguides, at least one of which is optically coupled to a third optical port and the mirror. Moreover, a length of the optical waveguide is chosen to match the round-trip optical path length in at least the one of the adjacent optical waveguides. During operation, control logic determines the reflectivity of the mirror based at least on a ratio of an optical power measured on one of the two optical ports to an input optical power on the third optical port.

A phase-resolved heterodyne shearing interferometer has been developed for high-rate, whole field observations of transient surface motion. The sensor utilizes polarization multiplexing and multiple carrier frequencies to separate each segment of a shearing Mach-Zehnder interferometer. Post-processing routines have been developed to recombine the segments by extracting the scattered object phase from Doppler shifted intermediate carrier frequencies, providing quantitative relative phase changes and information to create variable shear, phase resolved shearographic fringe patterns without temporal or spatial phase shifting.

A vacuum mechanism for flattening bowed panel samples includes a support structure with coplanar support elements and a fixture with a movable component actuated by a vacuum source. The movable component has a top surface disposed above the support elements when no vacuum is applied and is capable of being drawn to a substantially coplanar position with the support elements when actuated by the vacuum source. The top surface is fluidly connected to the vacuum source and adapted to adhere to the overlaying surface of the sample when vacuum is applied, thereby flattening the sample when the movable component is drawn in by the same vacuum source.

A vacuum mechanism for flattening bowed panel samples includes a support structure with coplanar support elements and a fixture with a movable component actuated by a vacuum source. The movable component has a top surface disposed above the support elements when no vacuum is applied and is capable of being drawn to a substantially coplanar position with the support elements when actuated by the vacuum source. The top surface is fluidly connected to the vacuum source and adapted to adhere to the overlaying surface of the sample when vacuum is applied, thereby flattening the sample when the movable component is drawn in by the same vacuum source.

Optical apparatus includes a primary radiation source, which emits first optical radiation along a first optical axis. A DOE includes at least an entrance surface, upon which the first optical radiation from the primary radiation source is incident, and an exit surface, through which one or more primary diffraction orders of the first optical radiation are emitted from the DOE. At least one secondary radiation source is configured to direct second optical radiation to impinge on the DOE along a second optical axis, which is non-parallel to the first optical axis, causing at least a part of the second optical radiation to be diffracted by the DOE such that one or more secondary diffraction orders of the second optical radiation are emitted through the entrance face of the DOE. At least one detector is configured to sense at least one of the secondary diffraction orders of the second optical radiation.

An apparatus for measuring the optical performance characteristics and dimensions of an optical element comprising a low coherence interferometer and a Shack-Hartmann wavefront sensor comprising a light source, a plurality of lenslets, and a sensor array is disclosed. The low coherence interferometer is configured to direct a measurement beam along a central axis of the optical element, and to measure the thickness of the center of the optical element. The light source of the Shack-Hartmann wavefront sensor is configured to emit a waveform directed parallel to and surrounding the measurement beam of the interferometer, through the plurality of lenslets, and to the sensor array. A method for measuring the optical performance characteristics and dimensions of a lens using the apparatus is also disclosed.