DONALD H MCMAHON
Broker in Carlisle, MA

4707061, Nov 17, 1987

Oct 3, 1985

6/783436

Donald H. McMahon - Carlisle MA

Polaroid Corporation - Cambridge MA

G02B 628

350 9616

An optical communications system with terminal devices connected to an optical pathway for communications with one another. A system wide reference signal is introduced into the optical pathway by a reference signal generator for propagation throughout the system. Each terminal device includes a resonant cavity to support one of a plurality of available sets of resonant modes, each set having an associated free spectral range between resonant modes, and controls the resonant cavity structure to lock one of the resonant modes of the resonant cavity to the system wide reference signal. The resonant characteristics of the resonant cavity at each terminal device can be changed to vary the number of integral wavelengths supported in the resonant cavity. Plural terminal devices can communicate with one another to support a set of resonant modes common to one another with one mode of the common set locked to the system wide frequency reference.

4715028, Dec 22, 1987

Jun 13, 1986

6/874118

Donald H. McMahon - Carlisle MA
Gilbert L. Johnson - Marlborough MA

Polaroid Corporation - Cambridge MA

H04B 900

370 3

An optical communications system includes an optical bus and a plurality of terminal devices coupled to the bus and a reference signal generator for propagating a reference signal through the bus for use by all terminal devices in selecting one of a predetermined number of frequency distinct communications channels. The reference signal is frequency swept in a recurring manner between two fixed frequencies and is introduced onto the system bus, along with a system synchronization signal, for propagation to bus tap resonators associated with the terminal devices in the system. Each terminal device detects the moment at which the swept reference frequency passes through one of the resonant modes of its bus tap resonator and determines the elapsed time thereof from the system synchronization signal. The respective bus tap resonator can be controlled, for example, by controlling its operating temperature, so that the reference frequency passes through the resonant mode of the terminal devices bus tap resonator at a selected time after the occurrence of the system synchronization signal to thus correspond to a frequency distinct communications frequency.

4516837, May 14, 1985

Feb 22, 1983

6/468526

Richard A. Soref - Newton Centre MA
Donald H. McMahon - Carlisle MA

Sperry Corporation - New York NY

G02F 113

350347V

An optical 1. times. N switch uses a polarizing beam splitter cube and a reflector to separate an arbitrarily polarized incident light beam into polarized components which propagate along parallel paths. A polarization rotator is positioned in the path of the reflected component to rotate the plane of polarization of the light beam component propagating therealong to be coplanar with that of the undeviated light beam in the parallel path. The two beams are simultaneously or individually deflected by selectively activating the electrodes of a liquid crystal nematic reflector/transmitter array confined between prismatic bodies to emerge at one or more of a plurality of desired outputs. In a second embodiment, a second polarization rotator and polarizing beam combiner assembly re-establishes the initial polarization and the beams are thereby combined to emerge from one or more selected output terminals as an arbitrarily polarized light beam. The switch exhibits extremely low crosstalk and insertion loss by utilizing the energy of both parallel and normal incidence polarization components and avoiding propagation of undesired stray polarization components as occurs with a liquid crystal polarizer.

4730301, Mar 8, 1988

Dec 20, 1985

6/811775

Donald H. McMahon - Carlisle MA

Polaroid Corporation - Cambridge MA

H04B 900

370 2

An optical fiber communications system includes a closed loop birefringent optical fiber bus for supporting optical energy propagated in a first and a second orthogonal polarization state. An optical energy source introduces a fixed frequency system wide carrier onto the optical fiber bus in a first polarization state for propagation in a first direction. Terminal devices coupled to the optical fiber bus include a bus tap resonator for removing a portion of the system wide carrier light and, in addition to modulating the removed light, effecting a frequency shift to a side frequency and effecting a state shift from the first to the other polarization state, and returning the information bearing optical energy to the optical fiber bus for propagation in a direction opposite to the first direction. A receiving device includes a bus tap resonator for removing a portion of the light from the bus and effecting demodulation to recover the information bearing signal.

4432599, Feb 21, 1984

Mar 27, 1981

6/248615

Donald H. McMahon - Carlisle MA

Sperry Corporation - New York NY

G02B 516

350 9615

An optical differential sensor utilizes at least two optical waveguides to receive light directly from another waveguide or reflected from a mirror to sense the position of the waveguide or reflector relative to the position of at least two waveguides. Relative positions may be influenced by ambient conditions or from mechanical motions, thus affecting an environmental or metrical sensor.

5208692, May 4, 1993

Jul 31, 1991

7/738665

Donald H. McMahon - Carlisle MA

Digital Equipment Corporation - Maynard MA

H04J 1402, H04B 1020

359128

A network interconnection architecture for a plurality of nodes uses sets of grouped node connections which form a plurality of node groups. A central electrically passive interconnection hub is coupled via a signal transmission path to each node group to establish a full mesh coupling between each of the plurality of node groups. An input and output matrix switch along with a pair of 1. times. N multiplexers are also coupled to each of the plurality of node groups and the hub multiplexer via the signal transmission path. The architecture can be further extended to encompass other networks with electrically passive hubs using a sandwich coupling of a matrix switch between two wavelength multiplexers.

4152723, May 1, 1979

Dec 19, 1977

5/861753

Donald H. McMahon - Carlisle MA
Colin G. Whitney - Woodland Hills CA

Sperry Rand Corporation - New York NY

H04N 718

358106

A method and apparatus for generating a digital image representation of a printed circuit board. The board has a substrate of insulating material. A pattern of metallic conductors is disposed on a surface of the insulating material. A beam of light energy scans this surface in a predetermined pattern. The beam has an energy level high enough to induce a detectable fluorescence in the surface of the insulating material. This fluorescence is detected and a binary signal is generated to indicate the presence or absence of fluorescence as the beam scans the surface. The binary signal is synchronized with the scanning of the beam such that a binary image representation of the board's surface is provided.

4116534, Sep 26, 1978

Apr 4, 1977

5/784087

Donald H. McMahon - Carlisle MA

Sperry Rand Corporation - New York NY

G03B 2716, B02B 2717

350157

A method and apparatus for rapidly changing the spatial modulation imposed on a stationary light beam to conform to a preselected one of a multiplicity of discrete character symbols. Automatic orientation tracking is provided which establishes a fixed direction for the spatially modulated light beam that is independent of the character accessed and provides a fixed position for the character image. The technique may be employed in electrographic high speed printers and has particular utility when used with standard character generating template masks for character generation, though it is also effective when employed with a holographic generating mask array.

4518857, May 21, 1985

Mar 7, 1983

6/473170

Donald H. McMahon - Carlisle MA
William B. Spillman - Acton MA

Sperry Corporation - New York NY

G02F 101

250225

A pressure and temperature compensated acoustic transducer utilizing a pressure sensitive birefringent element coupled between a flexible diaphragm sealing the transducer and an internal variable rigid diaphragm that forms two internal chambers. Relatively rapid variation in pressure applied to the birefrigent element cause fluctuations in the phase difference between orthogonal components of a polarized light beam traversing the photo-elastic material. Detections of this phase difference variation provides signals representative of incident acoustic signals. Provision for the transfer of liquid filling the chambers permits the equalization between the two chambers of slowly varying internal pressures caused by changes in external ambient pressure and temperature.

4021097, May 3, 1977

Mar 8, 1976

5/664727

Donald H. McMahon - Carlisle MA

Sperry Rand Corporation - New York NY

G02B 514

350 96C

An optical coupling apparatus having first and second optical waveguides wherein optical signals are coupled therebetween in a distributive manner. The distributive coupling provides essentially equally distributed optical signals in the secondary guide while maintaining an essentially continuous flow of light in the primary guide.