Abstract: A free space optical (FSO) communication node communicates via an FSO link with a remote FSO communication node that moves relative to the FSO node. The FSO node may be highly directional, and transmit (Tx) and receive (Rx) beams of the FSO node may share optical paths (at least in part). Instead of directing a Tx beam along a point ahead angle relative to a Rx beam (which may result in undesirable Rx coupling losses), the Tx beam is directed based on the point ahead angle and a point ahead offset angle. The point ahead offset angle modifies the point ahead angle to reduce Rx coupling losses while keeping Tx pointing losses at least low enough to maintain the FSO link. In some cases, due to the point ahead offset angle, the Tx direction minimizes a sum of the Rx coupling losses and the Tx pointing losses.

Abstract: A free-space optical (FSO) terminal may include a controller and an alignment sensor. The alignment sensor includes a set of detectors. Each detector generates a signal responsive to receiving electromagnetic radiation at a detection surface. The set of detectors includes an inner set of detectors and an outer set of detectors. The detection surfaces of the inner detectors and the outer detectors may be aligned in a plane. The outer set of detectors surround the inner set of detectors (e.g., in the plane) and have larger detection surfaces than the inner set of detectors. During a tracking mode, the controller is configured to adjust an orientation of the FSO terminal based on signals from the inner set of detectors. During an acquisition mode, the controller is configured to adjust the orientation of the FSO terminal based on signals from the outer set of detectors.

Abstract: Embodiments relate to a free space optical (FSO) terminal that transmits and receives optical beams. The FSO terminal includes a fore optic and a rotatable dispersive optical component. A receive (Rx) optical beam from the remote FSO communication terminal is received through the fore optic, and a transmit (Tx) optical beam is transmitted through the fore optic. The dispersive optical component is positioned along the optical paths of both the Rx and Tx optical beams. Since the Rx and Tx optical beams have different wavelengths and the dispersive optical component has a wavelength dependence, the dispersive optical component creates an angular separation between the Rx and Tx optical beams. The controller controls the rotational position of the dispersive optical component (and possibly also the wavelength of the Tx optical beam) to achieve a desired angular separation between the Rx and Tx optical beams.

Abstract: Embodiments relate to a free space optical (FSO) terminal that transmits and receives (e.g., data-encoded) optical beams. The FSO terminal includes a fore optic (e.g., telescope) and a chromatic Risley prism pair. A receive (Rx) optical beam is received through the fore optic, and a transmit (Tx) optical beam is transmitted through the fore optic. The chromatic Risley prism pair is positioned along the optical paths of both the Rx and Tx optical beams. Since the Rx and Tx optical beams have different wavelengths and the chromatic Risley prism pair has a wavelength dependence, the chromatic Risley prism pair creates an angular separation between the Rx and Tx optical beams. A controller controls the Risley prism pair (and possibly also the wavelength of the Tx optical beam) to achieve a desired angular separation between the Rx and Tx optical beams in free space.

Abstract: Embodiments relate to a bidirectional free space optical (FSO) communications system. Specifically, data-encoded FSO beams are transmitted and received between two terminals. A transmit (Tx) direction of a beam transmitted from the first terminal is dithered by a beam steering unit (BSU). As the dithered beam is received by the second terminal, the power levels of the beam are measured. The power levels are then encoded in a data-encoded FSO beam transmitted to the first terminal. This allows the first terminal to decode the received FSO beam and determine the power levels. The power levels allow the first terminal to determine Tx direction misalignments and adjust the Tx direction for the Tx beam sent to the second terminal. This process may be repeated to reduce Tx misalignments and may be performed by both terminals such that each terminal sends power level information to the opposite terminal.

Abstract: Embodiments relate to a free space optical (FSO) terminal that transmits and receives optical beams. The FSO terminal includes a fore optic and a rotatable dispersive optical component. A receive (Rx) optical beam from the remote FSO communication terminal is received through the fore optic, and a transmit (Tx) optical beam is transmitted through the fore optic. The dispersive optical component is positioned along the optical paths of both the Rx and Tx optical beams. Since the Rx and Tx optical beams have different wavelengths and the dispersive optical component has a wavelength dependence, the dispersive optical component creates an angular separation between the Rx and Tx optical beams. The controller controls the rotational position of the dispersive optical component (and possibly also the wavelength of the Tx optical beam) to achieve a desired angular separation between the Rx and Tx optical beams.

Abstract: Embodiments relate to a local free space optical (FSO) terminal that transmits and receives optical beams. The FSO terminal includes a fore optic, an optical relay system, and an actuator system. The fore optic focuses a receive (Rx) beam to a Rx spot on a focal plane of the fore optic. The focal plane also includes a Tx spot formed by a transmit (Tx) optical beam, however the Rx and Tx spots are laterally separated at the focal plane. The optical relay system creates a conjugate spot for the Rx or Tx spot so that the Rx and Tx fibers may be axially separated. Due to the axial separation, the actuator system can adjust a lateral separation of the Rx and Tx fibers to account for point ahead of the local FSO communication terminal.

Abstract: A local free space optical (FSO) terminal senses an external environment that includes at least two beacons transmitted from a remote FSO terminal. The local terminal is configured to sense the beacons at a frame rate. Each beacon comprises a pulse train with pulses that are transmitted at a pulse rate. The pulse trains are temporally offset relative to each other so that pulses from at least one of the pulse trains do not fall across frame boundaries during sensing, regardless of a temporal location of the frame boundaries. In addition to detecting the at least two beacons, the local terminal is configured to identity the beacon that contains pulses that do not fall across the frame boundaries, and adjust its orientation based on the identified beacon.

Abstract: Embodiments relate to a free space optical (FSO) communications system with a feed-forward control path. A data-encoded FSO beam is transmitted from a local terminal to a remote terminal. The local terminal directs a propagation direction of the FSO beam by a beam steering unit. To reduce pointing errors between the terminals, the FSO communications system includes a feed-forward control path. The control path includes an inertial measurement unit (IMU) that outputs motion data indicative of motion of the local terminal, for example if the local terminal is mounted to a tower that sways. The control path also includes a controller that receives the motion data from the IMU and generates feed-forward control signals for the beam steering unit. The control signals compensate for an effect of the motion of the local terminal on the propagation direction of the FSO beam.

Abstract: A system, such as a head-mounted display (HMD), displays images to a user. The system has an active state and an idle state. The system includes a display device, a beam combiner, and a user-operated control. The display device displays images when the system is in the active state and emits a reduced amount or no light when the system is in the idle state. The beam combiner provides a first optical path for light from an external environment to the user's eye and also provides a second optical path for light emitted from the display device to the user's eye. Responsive to activation by the user, the control switches the system between states that include the active state and the idle state, where the idle state is a default state and the system remains in the active state only while the user-operated control remains activated by the user.

Abstract: Embodiments relate to a bidirectional free space optical (FSO) communications system. Specifically, data-encoded FSO beams are transmitted and received between two terminals. A transmit (Tx) direction of a beam transmitted from the first terminal is dithered by a beam steering unit (BSU). As the dithered beam is received by the second terminal, the power levels of the beam are measured. The power levels are then encoded in a data-encoded FSO beam transmitted to the first terminal. This allows the first terminal to decode the received FSO beam and determine the power levels. The power levels allow the first terminal to determine Tx direction misalignments and adjust the Tx direction for the Tx beam sent to the second terminal. This process may be repeated to reduce Tx misalignments and may be performed by both terminals such that each terminal sends power level information to the opposite terminal.

Abstract: Embodiments relate to a free space optical (FSO) communication terminal. The terminal includes an optical source and optics. The optical source can produce optical beams at different wavelengths. The optics direct optical beams in a direction towards a remote FSO communication terminal. A wavelength dependence of the optics results in a divergence of the optical beam that depends on a wavelength of the optical beam. A controller may control the wavelength of the optical beam produced by the optical source, thereby adjusting the divergence of the optical beam (e.g., according to an acquisition process or a tracking process).

Abstract: Described is a free space optical (FSO) node capable of communicating with a remote FSO node. The FSO node includes a Tx/Rx subassembly that is capable of simultaneously receiving and transmitting light carrying data, detecting the position/orientation of the received light signals, and aligning the Tx/Rx subassembly to account for misalignments with remote node. The Tx/Rx subassembly includes a central fiber for transmitting and receiving the optical signals so that the signal data can be processed. The Tx/Rx subassembly also includes a bundle of fibers that circumscribe the central fiber and receive a portion of received light signals to detect the position/orientation of the received light signals and align the FSO node with a remote FSO node.

Abstract: Embodiments relate to a high power supercontinuum (SC) fiber optical source. The SC fiber optical source includes a prebroadening optical fiber that broadens the spectrum of a lower power intermediate optical signal before final amplification. The spectrum broadening creates spectral components which facilitate further spectrum broadening of amplified signal in final nonlinear stage, allowing to achive flatter and wider spectrum, and reduces nonlinear Stimulated Brillouin Scattering (SBS) that could damage SC fiber optical source components or limit the output power of the SC fiber optical source signal, thus enabling higher output power. After amplification in booster, passing at least part of broadened spectrum, the optical signal spectrum is further broadened by injecting the optical signal into a nonlinear stage to create a SC optical signal.

Abstract: A wide field of view night vision system is described. The system comprises a head attachment apparatus configured to attach to a user's head and a night vision subsystem. The night vision subsystem comprises one or more night vision image sensors attached to the head attachment apparatus. Each sensor receives input light and produces a digital image of the input light. A processor processes the digital image(s) to produce a wide-field image. The wide-field image spans at least 60 degrees of a user's horizontal field of view. A display and eyepiece attached to the head attachment apparatus receives and displays the wide-field image. The eyepiece is positionable between the display and the user's eye to image the wide-field image into the user's eye.

Abstract: A thermoelectric module for cooling a heat source includes multiple major sections, each major section including multiple minor sections. Each minor section includes one or more thermoelectric cooler (TEC) units including P-type and N-type semiconductors. Each major section also includes a single output terminal commonly connected to the minor sections, where the output terminal is configured to provide a same reference voltage signal to each of the minor sections. Each major section also comprises multiple input terminals, where each input terminal is separately connected to one of the minor sections and each input terminal is configured to provide a separate input voltage signal to each of the minor sections. The module also comprises a controller configured to independently control each reference voltage signal applied to each major section, and independently control each input voltage signal applied to each input terminal of each minor section within each major section.

Abstract: Apparatus and method of reducing light leakage from display devices are described. An embodiment of reducing light leakage from display devices includes providing an optical shutter that is configured to block light from a display device from being emitted into the ambient environment when the display device is in a bright state and configured to display visual information to the user. The optical shutter can be configured to transmit light from the ambient environment to the user when the display device is not displaying visual information.

Abstract: Described is a free space optical (FSO) node capable of communicating with a remote FSO node. The FSO node includes a Tx/Rx subassembly that is capable of simultaneously receiving and transmitting light carrying data, detecting the position/orientation of the received light signals, and aligning the Tx/Rx subassembly to account for misalignments with remote node. The Tx/Rx subassembly includes a central fiber for transmitting and receiving the optical signals so that the signal data can be processed. The Tx/Rx subassembly also includes a bundle of fibers that circumscribe the central fiber and receive a portion of received light signals to detect the position/orientation of the received light signals and align the FSO node with a remote FSO node.

Abstract: A detector configuration for use in a free space optical (FSO) node for transmitting and/or receiving optical signals has a plurality of sensors for detecting received optical signals. The plurality of sensors is configured along a common optical path and are used for separate functions. According, the detectors may be optimized for the respective function.

Abstract: Systems and methods of multiplexing information from a plurality of monochrome sensors/cameras is provided. The systems and methods provided can be useful to achieve pixel-level time synchronization between information acquired by different monochrome sensors/cameras that are configured to view a scene from different viewing directions.