Abstract: A low cost, high reliability system for correcting aberrations in optical signals is disclosed. A foreoptic assembly, such as a telescope, receives an incoming optical signal and directs it to an active optical element, such as a fast steering mirror. The incoming optical signal is diffracted by a diffractive optical element to shape the image that is formed at a wavefront sensor, such as a quad-cell. The wavefront sensor measures a tip-tilt aberration of the incoming optical signal and the active optical element is adjusted to correct the measured aberration. An outgoing optical signal can be transmitted along substantially the same optical path as the incoming optical signal, but in the opposite direction. Thus, the aberration measured from the incoming optical signal can be automatically accounted for in the outgoing optical signal.

Abstract: An encoding system encodes 8-bit data and control characters into 10-bit symbols. The 10-bit symbols have odd parity such that a single bit error results in an illegal code. Each 8-bit character maps either to a 10-bit symbol with balanced disparity or a pair of 10-bit symbols that collectively have balanced disparity. By periodically inserting an idle character that includes a run of seven consecutive like bits, a 1 MHz pilot tone is embedded in the data stream. The boundary of 10-bit symbols can be identified by locating a run of seven consecutive characters. 10-bit control symbols corresponding to 8-bit control characters are transmitted without reducing the bandwidth available for data transmission by replacing some or all of the preamble or idle portions of an Ethernet packet with the 10-bit control symbols.

Abstract: A free-space optical transceiver includes a repositionable mirror for receiving and sending light beams with another transceiver. To properly align the light beams, the position of the mirror is determined in using a position sensor. The position sensor is mounted within a base substructure that is coupled to a steerable mirror substructure containing the mirror. The position sensor reflects sensor light off of the mirror to determine the position of the mirror along two different axes. The position sensor includes an optical element for shaping the sensor light. The components of the position sensor are mounted to the base substructure such that alignment of the position sensor is not required. Further, by coupling the position sensor to the base substructure and not the steerable mirror substructure, the moment of inertia and center of gravity of the steerable mirror substructure is improved, thereby improving the steering responsiveness of the mirror.

Abstract: Methods and systems are described for determining and providing instructions for manual adjustment of a tilt angle of a radio frequency/free space optical transceiver system. Specifically, these instructions are provided for adjusting a tilt angle of a transceiver system using a tilt adjustment so that the transceiver system is approximately at a center of a range of motion of a gimbal assembly. A user interface in communication with a computing system of the local transceiver system provides instructions so that the above-described adjustments are implemented accurately and precisely. This tilt adjustment improves the reliability of the communication network because the gimbal assembly is able adjust the position of the transceiver system during relative movement between the transceivers system, thus maintaining the link despite the relative movement.

Abstract: A local communications apparatus is aligned with a remote apparatus, each apparatus comprising radio frequency (RF) and free space optical (FSO) transceivers with substantially parallel boresight. Coarse alignment is performed using the RF transceiver and fine alignment is performed using the FSO transceiver. A patterned search is performed to locate the RF signal from the remote apparatus and known features of the intensity profile are utilized to locate the global maximum, thus coarsely aligning the pair of apparatuses. A second patterned search is performed to locate the FSO signal from the remote apparatus and an iterative step-search is used to align the FSO signal centroid with the FSO transceiver, thus finely aligning the pair of apparatuses.

Abstract: A Cassegrain telescope uses a pivoted corrector plate to reduce back-reflections. A converging lens is added to the optical path inside a housing of the telescope to focus the light within the telescope. The modified Cassegrain design may be used a hybrid radio frequency and free-space optical commercial communications network.

Abstract: A stabilized ultra-high bandwidth capacity transceiver system that combines an E-band (71-76 GHz, 81-86 GHz) millimeter wave RF transceiver with an eye-safe adaptive optics Free Space Optical (FSO) transceiver as a combined apparatus for simultaneous point-to-point commercial communications. The apparatus has a high degree of assured carrier availability under stressing environmental conditions. The apparatus establishes and maintains pointing and stabilization of mmW RF and FSO optical beams between adjacent line of sight apparatuses. The apparatus can rapidly acquire and reacquire the FSO optical carrier link in the event the optical carrier link is impaired due to adverse weather.

Abstract: Methods and systems are described for determining and providing instructions for manual adjustment of a tilt angle of a radio frequency/free space optical transceiver system. Specifically, these instructions are provided for adjusting a tilt angle of a transceiver system using a tilt adjustment so that the transceiver system is approximately at a center of a range of motion of a gimbal assembly. A user interface in communication with a computing system of the local transceiver system provides instructions so that the above-described adjustments are implemented accurately and precisely. This tilt adjustment improves the reliability of the communication network because the gimbal assembly is able adjust the position of the transceiver system during relative movement between the transceivers system, thus maintaining the link despite the relative movement.

Abstract: Methods and systems for improving the quality of transmitted data are described. Multiple distinct communication channels are used to transmit segments representing the same pre-transmission block of a data packet. Upon receipt of these segments, a system identifies differences between the segments for those segments that meet a quality threshold. The system selects one of segments for subsequent transmission or re-assembly into a data packet based on the prior performance of the communication channels used to transmit the segments.

Abstract: A mechanism for retrieval of carrier frequency and carrier phase in a received modulated carrier waveform. Retrieval of carrier frequency and carrier phase can be implemented in an analog electrical circuit, using a field programmable gate array (FPGA), or in computer code. Independent of the implementation, the mechanism performs frequency and primary phase recovery by forcing transforms of a pilot tone in the upper and lower sidebands to the same frequency using a feedback loop. The difference-in-magnitudes of the channelized pilot are used by a phase lock loop to perform secondary phase recovery in a manner that also resolves phase sign ambiguity. Benefits of this mechanism include improved phase lock loop tracking performance and a reduction of noise in the data demodulated from the received carrier waveform.

Abstract: A communications networking having reduced transmission latency and improved reliability is described. To reduce signal transmission latency, network management data is removed from a data stream to prioritize the transmission of payload data at higher transmission rates. Management data is returned to the data stream in such a way that it minimizes an impact to payload transmission rates. To improve communications network reliability, the network is configured to form a primary communication path and a redundant communication path. Upon failure of a transceiver at one node, the network engages redundant transceivers on a per-node basis thereby using a segment of the redundant communication path. The data stream is returned to the primary communication path upon circumvention of the failed transceiver.

Abstract: A mechanism for retrieval of carrier frequency and carrier phase in a received modulated carrier waveform. Retrieval of carrier frequency and carrier phase can be implemented in an analog electrical circuit, using a field programmable gate array (FPGA), or in computer code. Independent of the implementation, the mechanism performs frequency and primary phase recovery by forcing transforms of a pilot tone in the upper and lower sidebands to the same frequency using a feedback loop. The difference-in-magnitudes of the channelized pilot are used by a phase lock loop to perform secondary phase recovery in a manner that also resolves phase sign ambiguity. Benefits of this mechanism include improved phase lock loop tracking performance and a reduction of noise in the data demodulated from the received carrier waveform.

Abstract: A mobile device is able to capture a plurality of different biometric identifiers of a subject. The mobile device displays a user interface on a screen of the device to guide the user in the capture of valid biometric identifiers. The user interface includes several different displays configured to guide users through the capture process to improve the chance that the user will capture valid biometric identifiers. The user interface includes displays for iris image capture, face image capture, voice capture, and fingerprint capture. The displays streamline the capture process, decreasing the overall knowledge and time required of the user to capture valid biometric identifiers. This also decreases the risk to the user in hostile environments. The device also processes the captured biometric identifiers to determine if they are valid, and updates the display of the user interface accordingly.

Abstract: A local communications apparatus is aligned with a remote apparatus, each apparatus comprising radio frequency (RF) and free space optical (FSO) transceivers with substantially parallel boresight. Coarse alignment is performed using the RF transceiver and fine alignment is performed using the FSO transceiver. A patterned search is performed to locate the RF signal from the remote apparatus and known features of the intensity profile are utilized to locate the global maximum, thus coarsely aligning the pair of apparatuses. A second patterned search is performed to locate the FSO signal from the remote apparatus and an iterative step-search is used to align the FSO signal centroid with the FSO transceiver, thus finely aligning the pair of apparatuses.

Abstract: A mobile device is able to capture a plurality of different biometric identifiers of a subject. The mobile device displays a user interface on a screen of the device to guide the user in the capture of valid biometric identifiers. The user interface includes several different displays configured to guide users through the capture process to improve the chance that the user will capture valid biometric identifiers. The user interface includes displays for iris image capture, face image capture, voice capture, and fingerprint capture. The displays streamline the capture process, decreasing the overall knowledge and time required of the user to capture valid biometric identifiers. This also decreases the risk to the user in hostile environments. The device also processes the captured biometric identifiers to determine if they are valid, and updates the display of the user interface accordingly.

Abstract: An optical circulator couples optical fibers of dissimilar modes. In one embodiment, an optical circulator couples a single mode first fiber to a multimode second fiber, which is used as an optical input to a telescope. The multimode fiber does not significantly degrade the mode structure of the light form the single mode fiber. In the reverse direction, light received by the telescope is coupled into the multimode second fiber, which the circulator couples to a multimode third fiber.

Abstract: An optical system includes an active focus element that maintains an image in focus over a range of object distances. The active focus element and aperture stop are positioned such that the image scale and the image spatial resolution are also invariant (or at least have a reduced sensitivity) with respect to object distance.

Abstract: A rapid iris acquisition, tracking, and imaging system can be used at longer standoff distances and over larger capture volumes, without the active cooperation of subjects. Eye reflections from the subjects' eyes are used to steer a high resolution camera to the eyes in order to capture images of the irises. A circular deformable minor driven by one or more annular forces can be used to focus the camera. A circular mirror substrate is mounted by its circumference onto a minor mount and driven by an annular drive element that contacts the minor substrate along a ring. If the annular drive element has a certain diameter relative to the circumference of the mirror substrate, the mirror substrate will be deformed in the shape of a sphere.

Abstract: The present invention provides a rapid, high quality iris imaging system. In one embodiment, on-axis illumination is used. A single steering mechanism steers both the camera and the illumination, without parallax issues. The illumination beam can be combined along the camera's optical axis before or after the fine steering and focus correction mechanism. In a pre-correction configuration, the iris illumination spot can be reduced in size to be only slightly larger than the iris. In both the pre and post-correction configuration, the eye safety limits will be most critical at the subject, which allows for maximization of the illumination flux.