Accelerometer with enhanced DC stability
First Claim
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1. An apparatus comprising:
- a substrate;
a first element;
an actuator, wherein the actuator induces a first motion of the first element with respect to the substrate;
a second element, wherein the second element comprises a first physical adaption for moving with a second motion in response to an acceleration;
a first sensor, wherein the first sensor provides a first signal that is based on the first motion; and
a second sensor, wherein the second sensor provides a second signal that is based on the second motion, wherein the second sensor comprises;
(a) a first optically resonant cavity, wherein the first optically resonant cavity has a first cavity length that is based a first separation between the second element and the substrate, and wherein the first optically resonant cavity receives light and distributes it into a first reflected signal and a first transmitted signal based on the first cavity length; and
(b) a first detector, wherein the first detector provides the second signal, and wherein the second signal is based on one of the first reflected signal and the first transmitted signal.
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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.
10 Citations
17 Claims
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1. An apparatus comprising:
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a substrate; a first element; an actuator, wherein the actuator induces a first motion of the first element with respect to the substrate; a second element, wherein the second element comprises a first physical adaption for moving with a second motion in response to an acceleration; a first sensor, wherein the first sensor provides a first signal that is based on the first motion; and a second sensor, wherein the second sensor provides a second signal that is based on the second motion, wherein the second sensor comprises; (a) a first optically resonant cavity, wherein the first optically resonant cavity has a first cavity length that is based a first separation between the second element and the substrate, and wherein the first optically resonant cavity receives light and distributes it into a first reflected signal and a first transmitted signal based on the first cavity length; and (b) a first detector, wherein the first detector provides the second signal, and wherein the second signal is based on one of the first reflected signal and the first transmitted signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus comprising:
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a substrate; a first element; a first tether, wherein the first tether physically couples the substrate and the first element, and wherein the first tether enables a first motion of the first element with respect to the substrate; an actuator, wherein the actuator induces the first motion; a first sensor, wherein the first sensor provides a first signal that is based on the first motion, and wherein the first sensor comprises; (a) a first optically resonant cavity, wherein the first optically resonant cavity has a first instantaneous cavity length that is based on a separation between the first element and the substrate, and wherein the first optically resonant cavity receives a first light signal and provides a second light signal that is based on the first instantaneous cavity length; and (b) a first detector, wherein the first detector provides the first signal based on the second light signal; a mass; a second tether, wherein the second tether physically couples the mass and the first element, and wherein the second tether enables the mass to move with a second motion in response to an acceleration; and a second sensor, wherein the second sensor provides a second signal that is based on the second motion. - View Dependent Claims (9, 10, 11, 12)
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13. A method comprising:
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inducing a first motion of a first element relative to a substrate; providing a first signal based on the first motion; enabling a mass to move with a second motion in response to an acceleration, wherein the mass is enabled to move with respect to the first element, and wherein the second motion is relative to the substrate; providing a first optical signal to a first optically resonant cavity having a first cavity length, wherein the first cavity length is based on a separation between the mass and the substrate, and wherein the first optically resonant cavity provides a second optical signal whose intensity is based on the first cavity length; and receiving the second optical signal at a first detector, wherein the first detector provides a second signal based on the second optical signal; and computing a value for the acceleration based on the first signal and the second signal. - View Dependent Claims (14, 15, 16, 17)
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Specification