Abstract: Embodiments of environmental stimulus sensors comprising multiple sources and detectors for interrogating one or more optically resonant cavities that are responsive to one or more environmental stimuli are disclosed. Such sensors have, among other advantages, improved immunity to source and/or detector noise.

Abstract: A gravimeter for detecting a gravity difference between two points is disclosed. The gravimeter comprises an interferometric arrangement wherein the length of a reference arm is dependent upon the gravity local to a first accelerometer and the length of a sample arm is dependent upon the gravity local to a second accelerometer. A pair of photodetectors that operate in complimentary fashion provide electrical signals based on a first signal conveyed by the reference arm and a second signal conveyed by the sample arm. A change in the differential gravity between the two points induces equal and opposite changes to the magnitudes of the two electrical signals.

Abstract: Embodiments of environmental stimulus sensors comprising multiple sources and detectors for interrogating one or more optically resonant cavities that are responsive to one or more environmental stimuli are disclosed. Such sensors have, among other advantages, improved immunity to source and/or detector noise.

Abstract: Embodiments of environmental stimulus sensors comprising multiple sources and detectors for interrogating one or more optically resonant cavities that are responsive to one or more environmental stimuli are disclosed. Such sensors have, among other advantages, improved immunity to source and/or detector noise.

Abstract: An accelerometer with improved immunity to sensitivity drift is disclosed. In some embodiments, the accelerometer comprises an actuator that induces a known acceleration on a reference frame. A signal based on this known acceleration is used to calibrate the accelerometer to mitigate the effects due to at least one of sensitivity drift, D.C. bias drift, sense laser wavelength drift, and resonant frequency drift.

Abstract: A method for forming a structure comprising multiple parallel surfaces having a precise separation is disclosed. Precise separation and parallelism of the surfaces is achieved through the use of an adhesive mixture that comprises a plurality of spacers having a dimension substantially equal to the desired separation.

Abstract: Embodiments of infrasound sensors comprising multiple matched-responsivity pressure sensors are presented. Infrasound sensors in accordance with the present invention have limited volume, which enables them to observe wind velocity at the same point that infrasound is monitored. The small size and matched-responsivities enable infrasound sensors in accordance with the present invention to obviate the need for complex and costly spatial filters that degrade the signal-to-noise ratio of prior-art infrasound sensors.

Abstract: An apparatus and method for discriminating a directional component of a propagating pressure wave using an array of operatively-coupled displacement sensors are disclosed. In accordance with the illustrative embodiment, each displacement sensor in the array comprises two parallel layers, at least one of which is movable. The output signal of each displacement sensor is based on the separation of the layers. The displacement sensors are operatively-coupled through a compressible fluid such that the response of one of the sensors to an input can cause an output signal in at least one of the other sensors. The operative-coupling of the displacement sensors amplifies relative phase information between their respective output signals, which results in improved directionality. Some embodiments of the present invention are particularly well-suited for use in microphones.

Abstract: An optical displacement sensor is disclosed comprising a beam splitter having two optically coupled and mechanically coupled optically resonant cavities. The respective cavity lengths of the optically resonant cavities are functions of an environmental stimulus. By virtue of the optically coupled optically resonant cavities, the output of the beam splitter is less sensitive to input wavelength variation yet retains high sensitivity to the environmental stimulus.

Abstract: Embodiments of environmental stimulus sensors comprising multiple sources and detectors for interrogating one or more optically resonant cavities that are responsive to one or more environmental stimuli are disclosed. Such sensors have, among other advantages, improved immunity to source and/or detector noise.

Abstract: A gravimeter for detecting a gravity difference between two points is disclosed. The gravimeter comprises an interferometric arrangement wherein the length of a reference arm is dependent upon the gravity local to a first accelerometer and the length of a sample arm is dependent upon the gravity local to a second accelerometer. A pair of photodetectors that operate in complimentary fashion provide electrical signals based on a first signal conveyed by the reference arm and a second signal conveyed by the sample arm. A change in the differential gravity between the two points induces equal and opposite changes to the magnitudes of the two electrical signals.

Abstract: An accelerometer with improved immunity to sensitivity drift is disclosed. In some embodiments, the accelerometer comprises an actuator that induces a known acceleration on a reference frame. A signal based on this known acceleration is used to calibrate the accelerometer to mitigate the effects due to at least one of sensitivity drift, D.C. bias drift, sense laser wavelength drift, and resonant frequency drift.

Abstract: An accelerometer based on an optical displacement sensor is disclosed. An embodiment of the present invention directs a light beam toward an optically resonant cavity and detects both the reflected and transmitted optical beams that result from interaction with the optically resonant cavity. The optically resonant cavity has a cavity length that is based on the position of a proof mass that moves in response to an acceleration.

Abstract: An optical displacement sensor for sensing an environmental stimulus is disclosed. The optical displacement sensor exhibits an optical design that has suppressed back reflection and improved alignment tolerance between its optical components. The sensor is based on an optically resonant cavity whose cavity length is affected by the environmental stimulus. An embodiment of the present invention utilizes a lens to redirect a first light signal toward an optically resonant cavity such that the light is incident on the cavity at a non-normal angle of incidence.

Abstract: An apparatus and method for detecting multiple beams from a beamsplitter is disclosed. Some embodiments of the present invention are particularly well-suited for use in microphones, high-sensitivity pressure sensors, vibration sensors, and accelerometer applications. Some embodiments of the present invention generate a differential electrical output signal that is based on multiple detected optical signals. The differential output signal is generated in response to an environmental stimulus, such as a pressure differential or incident acoustic energy. In accordance with the illustrative embodiment, an optical displacement sensor redirects the transmitted beam back through the optically-resonant cavity with an angular offset. Due to the angular offset, the redirected beam (i.e., retransmitted beam) transits the cavity with an intra-cavity path length that corresponds to substantially full transmittance of the retransmitted beam in the absence of the environmental stimulus.

Abstract: An optical displacement sensor is disclosed comprising a beam splitter having two optically coupled and mechanically coupled optically resonant cavities. The respective cavity lengths of the optically resonant cavities are functions of an environmental stimulus. By virtue of the optically coupled optically resonant cavities, the output of the beam splitter is less sensitive to input wavelength variation yet retains high sensitivity to the environmental stimulus.

Abstract: A method for forming a structure comprising multiple parallel surfaces having a precise separation is disclosed. Precise separation and parallelism of the surfaces is achieved through the use of an adhesive mixture that comprises a plurality of spacers having a dimension substantially equal to the desired separation.

Abstract: An optical displacement sensor is disclosed that provides a optical displacement sensor that includes a optically-resonant cavity tuned to an operating wavelength without some of the disadvantages for doing so in the prior art. An embodiment of the present invention tunes an operating wavelength used with a Fabry-Perot interferometer to develop a desired relationship between the wavelength and the Fabry-Perot interferometer's initial cavity length.

Abstract: An optical displacement sensor for sensing an environmental stimulus is disclosed. The optical displacement sensor exhibits an optical design that has suppressed back reflection and improved alignment tolerance between its optical components. The sensor is based on an optically resonant cavity whose cavity length is affected by the environmental stimulus. An embodiment of the present invention utilizes a lens to redirect a first light signal toward an optically resonant cavity such that the light is incident on the cavity at a non-normal angle of incidence.

Abstract: An accelerometer based on an optical displacement sensor is disclosed. An embodiment of the present invention directs a light beam toward an optically resonant cavity and detects both the reflected and transmitted optical beams that result from interaction with the optically resonant cavity. The optically resonant cavity has a cavity length that is based on the position of a proof mass that moves in response to an acceleration.