A liquid crystal device includes a front electrode layer, a rear electrode layer, and a liquid crystal material located between the front electrode layer and the rear electrode layer. A first and second transistor each includes three terminals. The first transistor is a photo transistor. The first terminal of the first transistor electrically interconnected to a conductive electrode free from additional electrical elements therebetween. The second terminal of the first transistor is electrically interconnected to the conductive electrode free from additional electrical elements therebetween and the second terminal of the first transistor is maintained at the same potential as the conductive electrode. The first terminal of the first transistor and the second terminal of the first transistor electrically interconnected to one another free from additional electrical elements therebetween and the first terminal of the first transistor and the second terminal of the first transistor are maintained at the same potential. The second terminal of the first transistor is a gate of the first transistor. The third terminal of the first transistor electrically interconnected to the first terminal of the second transistor free from additional electrical elements therebetween and maintained at the same potential. The second transistor provides a readout function for the circuit. The second terminal of the second transistor electrically connected to one of the select electrodes. The second terminal of the second transistor is a gate of the second transistor. The third terminal of the second transistor is electrically interconnected to a readout system. The second transistor is substantially inhibited from receiving ambient light thereon. The first transistor is not substantially inhibited from receiving ambient light thereon. The first transistor and the second transistor being together with the rear electrode layer. The readout system determines a region of the device that experiences a change in the light level impinging on the device.

Light sensitive display

Interference microscopy plays a central role in noncontact strategies for process development and quality control, providing full 3D measurement of surface characteristics that influence the functional behavior of manufactured parts. Here I briefly review the history and principles of this important technique, then concentrate on the details of hardware, software, and applications of interference microscopy using phase-shifting and coherence scanning measurement principles. Recent advances considered here include performance improvements, vibration robustness, full color imaging, accommodation of highly sloped surfaces, correlation to contact methods, transparent film analysis, and international standardization of calibration and specification.

Principles of interference microscopy for the measurement of surface topography

Optical coherence tomography with 3D coherence scanning is disclosed, using at least three fibers ( 201, 202, 203 ) for object illumination and collection of backscattered light. Fiber tips ( 1, 2, 3 ) are located in a fiber tip plane ( 71 ) normal to the optical axis ( 72 ). Light beams emerging from the fibers overlap at an object ( 122 ) plane, a subset of intersections of the beams with the plane defining field of view ( 266 ) of the optical coherence tomography apparatus. Interference of light emitted and collected by the fibers creates a 3D fringe pattern. The 3D fringe pattern is scanned dynamically over the object by phase shift delays ( 102, 104 ) controlled remotely, near ends of the fibers opposite the tips of the fibers, and combined with light modulation. The dynamic fringe pattern is backscattered by the object, transmitted to a light processing system ( 108 ) such as a photo detector, and produces an AC signal on the output of the light processing system ( 108 ). Phase demodulation of the AC signal at selected frequencies and signal processing produce a measurement of a 3D profile of the object.

Optical coherence tomography with 3d coherence scanning

Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser or welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.

Methods and systems for coherent imaging and feedback control for modification of materials

A system comprising a stack of layers configured to display an image and including multiple elements configured to sense light. The system is configured to obtain a first reference image based on output from the multiple elements in a dark lighting condition associated with the system, and calibrate object detection based on output from the multiple elements using the obtained reference image. Additionally, a system comprising a display having a stack of layers configured to display an image and including a first and second set of elements. Each of the elements in the first set is configured to sense light, and each of the elements in the second set is configured to sense a dark current. The system is configured to perform object detection based on output from the elements in the first set, and calibrate the object detection based on output from the elements in the second set.

Light sensitive display with object detection calibration

A laser diode (1) of a laser vibrometer emits light which is guided onto a polarization beam splitter (3) by a lens 2. A portion of the beam is guided through directly to an imaging lens (4) and a second portion is deflected onto a mirror (5). Quarter-wave plates (6) and (7) are arranged between the polarization beam splitter and respectively the lens or the mirror. The beam which is reflected on the mirror is guided completely through the polarization beam splitter onto a photodetector unit (8). The beam reflected by the object (9) to be measured, which swings in the direction (14), is also deflected to the photodetector unit. The output signal of the photodetector unit, the interference signal generated from the superposition of the two reflected beams, is supplied to an electronic evaluation equipment (10). The latter is also supplied with a signal of a current modulator (11) which, on the other hand, supplies the laser diode with modulated injection current via line (12). The distance between the imaging lens and the object to be measured forms an optical detour (13) which is considerably lengthened compared to the reference arm.

Laser vibrometer for vibration measurements

The invention relates to an interferometric measuring device (1) for determining the profile of rough surfaces. A spatially coherent beam generating unit is provided. Said unit emits temporally briefly coherent wideband radiation. The device is divided into a section with the components of a modulation interferometer (2) and a section with the components of a measuring probe (3). The measuring probe (3) is linked to the modulation interferometer (2) by an optical fibre system (6) and can be used at a distance from the modulation interferometer (2).

Interferometrische Meßeinrichtung zum Erfassen der Form oder des Abstandes insbesondere rauher Oberflächen

An interferometric measuring device for detecting the shape, roughness or distance of surfaces is described. The interferometric measuring device has a modulation interferometer in which two partial beams are formed, one of which is shifted in its light phase or light frequency with respect to the other by a modulation device. The surface is measured with a measuring probe which is connected to the modulation interferometer and in which a measuring beam and a reference beam are formed, and an interference pattern which is analyzed in a connected receiving unit is formed from the measuring beam and the reference beam. A compact design that is easy to handle even in a manufacturing process is achieved by spatially separating the modulation interferometer which is designed as a basic unit from the measuring probe and by the fact that it can be connected to the measuring probe by an optical fiber arrangement, and the measuring arm and the reference arm are formed by solids conducting the measuring beam and the reference beam.

Modulation interferometer and fiberoptically divided measuring probe with light guided

Laser processing device comprises: a laser processing unit (2) for producing a beam (2.1) deviated on a processing site of a workpiece (3); and a measuring system (4) having an illuminating unit and an observation unit for acquiring surface data of the workpiece in the region of the processing site. The measuring system is partially connected to the laser processing unit to acquire three-dimensional surface data or oscillations. The measuring system is in the form of a interferometer with a short coherent light source as white light interferometer. Preferred Features: Illumination and observation with the measuring system is in the same direction. A beam splitter (2.2) is arranged in the laser processing unit. The processing laser is used as the illumination unit.

Laser processing device used for laser welding, cutting or boring has a measuring system partially connected to the laser processing unit to acquire three-dimensional surface data or oscillations

Pawel Drabarek

Papers

Laser vibrometer for vibration measurements

Interferometrische Meßeinrichtung zum Erfassen der Form oder des Abstandes insbesondere rauher Oberflächen

Modulation interferometer and fiberoptically divided measuring probe with light guided

Laser processing device used for laser welding, cutting or boring has a measuring system partially connected to the laser processing unit to acquire three-dimensional surface data or oscillations

Interferometric measuring device for determining the profile or the pitch of especially rough surfaces