Abstract: A beam steering system having first diffraction gratings, each one being associated with a corresponding one of a first plurality of grating vectors disposed substantially in a first plane. The gratings diffract optical energy from any one of a plurality of input directions of resonance to a corresponding one of a plurality of output directions. Second diffraction gratings are associated with a second plurality of grating vectors disposed substantially in a second plane. Each one of the second gratings diffracts optical energy from any one of a plurality of input directions of resonance to a corresponding one of a plurality of output directions.

Abstract: A transmit/receive module including digitally controlled analog circuits is described. The digital circuits use a logic family adapted for use with analog monolithic integrated circuits. The disclosure also describes a preferred process to provide digital and analog microwave circuits on a common semiconductor substrate.

Abstract: A non-planar Q-switched ring laser system including a ring laser having a gain medium and a closed optical path lying in at least two distinct planes, and a Q-switch in the closed optical path for automatically varying the loss in the closed optical path.

Abstract: A phased array antenna system having an array of antenna elements coupled to radio frequency energy feed network through a plurality of phase shifter sections with digital control data being fed to the phase shifter sections with radio frequency energy signal modulated with the digital control data. A modulator is fed by the source of the radio frequency energy and a modulating signal to produce the modulated radio frequency energy signal. A modulating signal generator/encoder, fed by the digital control data, encodes each bit of such digital control data into the modulating signal, such modulating signal being a bipolar signal having a pair of electrical signal changes corresponding to a binary state represented by such bit. The modulated radio frequency energy signal may be fed to the demodulator through the radio frequency feed network or through the antenna element coupled thereto.

Abstract: A phased array antenna system having an array of antenna elements coupled to radio frequency energy feed network through a plurality of phase shifter sections with digital control data being fed to the phase shifter sections with radio frequency energy signal modulated with the digital control data. A modulator is fed by the source of the radio frequency energy and a modulating signal to produce the modulated radio frequency energy signal. A modulating signal generator/encoder, fed by the digital control data, encodes each bit of such digital control data into the modulating signal, such modulating signal being a bipolar signal having a pair of electrical signal changes corresponding to a binary state represented by such bit. The modulated radio frequency energy signal may be fed to the demodulator through the radio frequency feed network or through the antenna element coupled thereto.

Abstract: An ellipsoidal reflector is provided for a light energy emitting lamp which is used as a heating element within an oven. Because an ellipsoidal reflector is used, the light energy emitting lamp may be positioned at the first focal point of the ellipsoidal reflector in order to concentrate light reflected by the ellipsoidal reflector on the food being cooked. Accordingly, a charbroiled surface effect common to gas or electric cooking grills is produced. The light energy emitting lamp may also be moved away from the first focal point so that light is reflected by the ellipsoidal reflector more uniformly.

Abstract: A low cost automatic frequency control system measures short duration radio frequencies with high a degree of accuracy within 0.5 MHz. The system is programmable to allow applicability over a wide range of frequencies within the required accuracy and various signal durations. The system includes circuits to digitize the source signal to a digital pulse train and asynchronously sample the pulse train to obtain a count of the positive edges of the pulses over a sufficient number of samples. A microprocessor computes the statistical average of the count and accurately determines the frequency of the source signal. The system further includes a feedback path to implement correction to the source signal based on the measured frequency.

Abstract: A ring laser gyro uses a nonplanar path having at least one plane of mirror symmetry and two pathlength control mirrors in order to reduce scatter variations occurring during the operation of the laser gyro. The mirrors used to produce such path are fixed to an isotropic supporting block having passages therein that define the path segments and the mirrors are moved out or in by the expansion or contraction of the block. The two pathlength control mirrors are disposed diagonally opposite each other on the plane of mirror symmetry, and are placed on substrates whose positions are controllable, each substrate being coupled to means for controlling the positions of the substrates as a function of the pathlength. With such a mirror configuration, the pathlength may be held constant by a suitable control means and the relative movement of the mirrors constrains movement, with respect to the mirrors, of the beams circulating in the path to directions perpendicular to the planes of incidence on the mirrors.

Abstract: A ring laser gyro uses a nonplanar path having at least one plane of mirror symmetry and two pathlength control mirrors in order to reduce scatter variations occurring during the operation of the laser gyro. The mirrors used to produce such path are fixed to an isotropic supporting block having passages therein that define the path segments and the mirrors are moved out or in by the expansion or contraction of the block. The two pathlength control mirrors are disposed diagonally opposite each other on the plane of mirror symmetry, and are placed on substrates whose positions are controllable, each substrate being coupled to means for controlling the positions of the substrates as a function of the pathlength. With such a mirror configuration, the pathlength may be held constant by a suitable control means and the relative movement of the mirrors constrains movement, with respect to the mirrors, of the beams circulating in the path to directions perpendicular to the planes of incidence on the mirrors.

Abstract: A laser mirror mounting arrangement for a laser formed within a laser body is shown. The mounting arrangement includes a mounting base mounted upon the laser body. A stem is attached to the mounting base to which, in turn, the laser mirror is mounted. The stem has a coefficient of thermal expansion selected to maintain the mirror in a fixed position. This is accomplished by permitting the stem to expand due to thermal expansion in one direction, while the laser body expands due to thermal expansion in the opposite direction.

Abstract: A direct digital synthesizer (DDS) includes a phase accumulator which generates phase words periodically and means for changing the phase of an RF signal. In a preferred embodiment, a DDS includes a pair of phase shifter channels having inputs and outputs coupled in parallel by make before break RF switches. The use of the dual phase shifter channels and make before break RF switches provides relatively smooth phase advance while eliminating fly-back transitions. This arrangement reduces excessive noise power in the output signal.

Abstract: A laser gyro system wherein a plurality of nonplanar ring laser gyros are nested within a common supporting block of material. The nonplanar ring laser gyros have a ring path whose circumscribing volume has a size of the order of the volume of the supporting block, each ring path utilizing a portion of the volume unused by the other. In one embodiment, a cubic block contains two orthogonal tetrahedral ring laser gyros. The two rings intersect and share a common gas envelope. In another embodiment, the supporting block contains two orthohedral ring laser paths.

Abstract: A ring laser gyro uses a nonplanar equilateral (skew rhombus) ring path. In the preferred embodiment, the mirrors used to produce such path are mounted on a supporting cube having passages cut in the path of a beam of electromagnetic energy propagating therebetween. Preferably, the mirrors are positioned on the surface of the cube and produce a nonplanar equilateral ring path having path segments in two planes. In one embodiment, four mirrors are placed on the corners of the cube to define the vertices of a tetrahedron circumscribed by the cube. With such an arrangement, the sensitive axis is along one of the three mutually orthogonal principal axes of the cube. The tetrahedral ring is equiangular as well as equilateral; thus, all the incidence angles on the mirrors are the same.

Abstract: A four-frequency laser gyroscope system having improved accuracy is constructed using a single solid block of low thermal coefficient of expansion material. A four-segment nonplanar propagation path provides a first frequency splitting. A second splitting is provided by a Faraday rotator having a thin slab of rare earth-doped glass positioned within an aperture in a permanent magnet. A narrow angle of incidence is provided for the beams of incident upon the output mirror to prevent cross coupling between beams within the output optics structure. Blocking the gaseous flow path reduces output frequency drift caused by contaminating particles.

Abstract: A high contrast Brewster angle polarizing beamsplitter in which splitting occurs on the internal surface of a dielectric material having a higher-refractive-index than the surrounding medium. The Brewster angle resulting from the incidence of electromagnetic radiation on the dielectric interface of the higher-refractive-index material to the lower-refractive-index medium is smaller than the one attained when using the external surface and thus results in a more compact beamsplitter configuration. A beamsplitter structure is also provided for obtaining one of the transmitted components that is collinear with the original beam.

Abstract: An electromagnetic wave ring resonator is disclosed wherein field distribution of electromagnetic waves are spatially rotated about the direction of propagation of such waves in said resonator. With such arrangement the electromagnetic field distribution rotation produces a phase difference between waves of opposite polarization senses, thereby enabling the waves to resonate with different frequencies. In a laser gyroscope the electromagnetic field distribution may be achieved by a catoptric arrangement which reduces the loss, scatter and linear birefringence associated with the ring resonator of the gyroscope.

Abstract: A ring laser gyroscope system uses a non-planar path and no-depolarizing Faraday bias means to achieve four-frequency differential operation. The use of the non-planar path eliminates the crystal rotator normally used to provide reciprocal bias and therefore eliminates scattering surfaces and a major cause of thermal sensitivity. The non-depolarizing Faraday means, such as a thin glass slab having a component of magnetic field along the optic axis of the laser, is used to reduce the corresponding thermal sensitivity of the traditional Faraday bias element normally implemented by a crystal such as quartz. Eliminating these major sources of drift then allows higher-order sources of drift to be corrected. Zeeman splitting of the laser gain medium is used to provide an equal amount of dispersion to each of the two counter-travelling waves of each wave pair, thus eliminating small amounts of drift due to the different phase shifts produced in the propagating waves by the gain medium.

Abstract: A reflectometer for precisely measuring the reflectivities of mirrors by performing two sequential measurements each of which is related to a different function of the reflectivities of a reference mirror and the mirror under test. For the first measurement, the two mirrors are arranged so that a beam of light is reflected alternately from the reference mirror and from the test mirror to an output detector to produce an output signal related to the difference of the reflectivities. In the second measurement, the mirrors are positioned so that the beam passes to the output detector directly and, alternately, after reflection from first the reference mirror and then the test mirror, thereby producing an output signal related to the product of the reflectivities. The reflectivity of the test mirror is then calculated from the two output signal quantities.

Abstract: A laser system having an optically unstable cavity with a unique optical center axis longitudinally offset from the center axis of the cavity toward one side of the resonator to obtain an unobscured output beam from the opposite side. The resonator also has astigmatic magnification which provides for a greater volume utilization of the gain medium than otherwise possible. In a preferred embodiment, the off-axis astigmatic resonator employs spherical mirrors at off-normal incidence to provide for different magnification in two orthogonal planes.

Abstract: A four-frequency laser gyroscope system having improved accuracy is constructed using a single solid block of low thermal coefficient of expansion material. A four-segment nonplanar propagation path provides a first frequency splitting. A second splitting is provided by a Faraday rotator having a thin slab of rare earth-doped glass positioned within an aperture in a permanent magnet. A narrow angle of incidence is provided for the beams of incident upon the output mirror to prevent cross coupling between beams within the output optics structure. Blocking the gaseous flow path reduces output frequency drift caused by contamininating particles.