Abstract: A fiber-optic polarizer comprising the combination of an optical fiber having a core and cladding with different refractive indices and forming a single-mode guiding region, the core having a non-circular cross-section defining two transverse orthogonal axes which, in combination with the different refractive indices, permit the de-coupling of waves polarized along the axes, the guiding region being located sufficiently close to the surface of the fiber, along a selected length of the fiber, to allow coupling to a contiguous medium, and the outer surface of the fiber having a non-circular cross-section with a predetermined geometric relationship to the guiding region and the orthogonal transverse axes so that the location of the guiding region and the orientation of the axes can be ascertained from the geometry of the outer surface.

Abstract: A thermal ink jet printer utilizes a printhead resistor which has a central conductive region to excite bubble growth and to cause ejection of ink droplets. The existence of the central conductive region causes bubbles to be created which are toroidal in shape and which fragment during collapse, thereby randomly distributing the resultant acoustic shock across the surface of the printhead resistor and minimizing cavitation damage.

Abstract: A thermal ink jet printer is disclosed in which ink droplets are ejected from an orifice by the explosive formation of a vapor bubble within the ink supply due to the application of a two part electrical pulse to a resistor within the ink supply. The electrical pulse comprises a precurser pulse and a nucleation pulse; the precurser pulse preheats the ink in the vicinity of the resistor to a temperature below the boiling temperature of the ink so as to preheat the ink while avoiding vapor bubble nucleation within the ink supply and the subsequently occuring nucleation pulse very quickly heats the resistor to near the superheat limit of the ink.

Abstract: A time slot interchange switch matrix incorporates processor-controlled diagnostic functions to provide programmable on-line/off-line diagnostic monitoring. The switch matrix output can be tri-stated during program-selected time slots while remaining electrically connected to the PCM buses, allowing redundant switch matrices to share on-line time slot interchange switching in any programmable manner. Inject and monitor circuitry enables the switching function of the on-line switch matrix to be tested time slot by time slot under program control using unused time slots. Parity checking, including verification of check circuitry, is provided for input PCM data, control memory addressing output, and data memory output through the tri-state output drivers. In addition to on-line inject and monitor testing, the off-line switch matrix selectively monitors the output of the on-line matrix to confirm that it is driving the PCM buses.

Abstract: A digital information switching system features modular design with dispersed processing in which data is switched locally in one of a plurality of remote switching units for connection between local terminals, and data to be exchanged between terminals connected to different remote switching units is switched in a central switching unit, which is connected to the remote switching units by way of interswitch links. Both the central switching unit and the remote switching units are of the same general configuration being individually processor controlled. Reliability of each unit in the system is enhanced by diagnostic and maintenance features including provision of redundant devices in each unit, detection of device failures, automatic replacement of failed devices with redundant devices and communication of the failure to a remote service center.

Abstract: Pipe measuring apparatus is disclosed. In the preferred embodiment, a transmitter is arranged at one end and a receiver at the other end of the pipe. At the transmitter, there is a tone generator which transmits acoustic signal along the pipe. In addition, a power amplifier drives an output diode which transmits light of a specified frequency, and both are funneled along the pipe to be measured. At the receiving end, an amplifier picks up the sound. In like manner, the light which is transmitted through the pipe is also detected. Both detected signals are amplified. After amplification, their modulating envelopes are compared to one another. There is a time shift which is a function of transmission distance, treating the transmitted light as the reference. This time shift is converted by a scale factor into a multi-digit output. The conversion occurs through the use of a clock connected through a decimal counter which is gated on by the light signal and which is gated off by the advent of the sound signal.

Abstract: An acoustical horn speaker for producing low distortion sound comprised of a casing assembly having a voice coil gap and a magnetic source and return circuit for providing a constant magnetic field across the gap, a current-carrying voice coil disposed in said gap, and a voice diaphragm in rigid attachment with the voice coil, said voice diaphragm being suspended from the casing assembly by a relatively flexible, high compliance suspension member. An acoustical horn having a throat resistance sufficiently high to substantially dominate the radiation resistance of the diaphragm is air coupled at its throat end to the voice diaphragm suspended from said casing, while the compliance of the voice diaphragm suspension is relatively high such that in the presence of the dominating throat resistance of the horn the diaphragm vibratory movement is characterized by substantially force determinative excursions as opposed to substantially linear constant displacement excursions.