There is disclosed apparatus and a method for producing a selected visual pattern. A colliminated linearly-polarized laser beam of radiation, is passed in succession through, and subdivided into a matrix of potentially visual elements by, a pair of matrices of coextensive light-modulating cells, each cell matrix formed by crossed arrays of electro-optic crystals disposed with their optic axes at right angles to the beam and at right angles to each other. Voltage is impressed on selected crystals of each array of the first matrix to produce a phase shift of 90.degree. in the plane of polarization of the elements of the beam passed by these selected crystals. The beam emerging from the first cell matrix is passed through a linear polarizer whose polarization is in the same plane as the incident beam, the polarizer passes only elements of the beam which were modulated by crystals of both arrays and unmodulated elements. Voltage is impressed on crystals of each array forming the second matrix which are coextensive with the selected crystals of the first matrix; this voltage shifts the plane of polarization of the beam elements passed by both crystals of the second matrix by 90.degree.. The beam emerging from the second matrix is passed through a polarizer whose plane of polarization is at 90.degree. to the polarization of the incident beam. Only the elements of the beam which pass through the crystals of all four arrays emerges.
An optical voltage and electric field sensor for detecting the voltage or electric field applied to a device made of a single crystal of bismuth silicon oxide (Bi.sub.12 SiO.sub.20) or bismuth germanium oxide (Bi.sub.12 GeO.sub.20) is disclosed. The device comprises a plurality of crystal plates stacked in a direction perpendicular to the propagation direction of light, each plate having only one dimension reduced to a very small size.
A pair of uniaxial birefringent crystal elements are fixed together to form a serially arranged, integral assembly which, alternatively, provides either a linearly or elliptically polarized second-harmonic output wave or a linearly polarized third-harmonic output wave. The "extraordinary" or "e" directions of the crystal elements are oriented in the integral assembly to be in quadrature (90.degree.). For a second-harmonic generation in the Type-II-Type-II angle tuned case, the input fundamental wave has equal amplitude "o" and "e" components. For a third-harmonic generation, the input fundamental wave has "o" and "e" components whose amplitudes are in a ratio of 2:1 ("o":"e" reference first crystal). In the typical case of a linearly polarized input fundamental wave this can be accomplished by simply rotating the crystal assembly about the input beam direction by 10.degree.. For both second and third harmonic generation input precise phase-matching is achieved by tilting the crystal assembly about its two sensitive axes ("o").
An optical deflection device for manipulating optical beams employs a set of layers having the configuration NUPUN . . . , where the N and P symbols refer to N-type and P-type dopants and the U symbol refers to an electrooptically active optical guide layer having an index of refraction sufficiently higher than that of the N- and P- layers that light is guided within it and a free electron concentration low enough that the guide layers are depleted, so that light is guided within the layers with low loss, while the N- and P- layers have an appropriate bias applied to establish a differential phase shift between layers to deflect emitted radiation along a desired angle.
A light valve array having transversely driven electrooptic gates is disclosed, with the array having a substrate and a plurality of discretely addressable electrooptic gates mounted thereon. Each gate has two spaced parallel surfaces, one of which has an addressable electrode and the other surface is connected to a planar conductive surface on the substrate. When a potential is applied between a gate electrode and the conductive surface of the substrate, a uniform electric field is produced in such gate. The array is mounted in a notch on a circuit board such that the addressable electrodes are in electrical contact with a corresponding plurality of circuit board conductors, and the planar conductive surface is in electrical contact with another circuit board conductor. According to the disclosed method of making these arrays, a stack of plates of electrooptic material is releasably assembled and permanently attached to a stack of plates of substrate material similarly releasably assembled in a manner such that the corresponding plates are aligned edge-to-edge. The attached stacks are machined, metallized to provide the gate electrodes, and then the plates are separated to form a plurality of such transversely driven light valve arrays.
A device for compensating for changes in temperature and strain in electro-optic modulators without altering the voltage field effects. Devices for modulating light intensity in response to a varying electrical signal are particularly useful with optical fiber information sensing systems. Such modulators basically receive a light signal, collimate and polarize the light, then pass it through a wave plate to cause circular polarization. The light signal then is passed through a modulator material which rotates the beam polarization in response to varying voltage signals imposed on the modulator. Unfortunately, changes in temperature and strain also change the state of polarization. I have now found that by transmitting the light signal through two equal crystals in series that are rotated 180.degree. from each other, a uniform strain or temperature change will result in canceled polarization effects. Thus, effects of changes in temperature and/or strain are canceled without affecting the voltage field effects.
