The present invention discloses a MEMS gravimeter comprising: a spring-mass system, a displacement sensing structure, a displacement detecting circuit, a cavity body and a level adjustment base; the spring-mass system is disposed inside the cavity body and includes: a negative-stiffness spring, a positive-stiffness spring, a proof mass and an outer frame; the proof mass is connected to the outer frame by the negative-stiffness spring and the positive-stiffness spring, the negative-stiffness spring and the positive-stiffness spring are symmetrically disposed with respect to the proof mass, and the outer frame is fixedly connected to the cavity body; the displacement sensing structure is located on a surface of the proof mass, and the displacement detecting circuit is configured to detect a displacement signal from the displacement sensing structure; the spring-mass system realizes reduction in resonant frequency by matching of the positive and negative stiffness springs; and change in gravitational acceleration is detected by detecting a displacement of the proof mass. The MEMS gravimeter has high stability, small size and light weight, and thus can effectively reduce the production cost as well as the development difficulty of the signal detection unit and stable platform.

The present invention discloses a MEMS gravimeter comprising: a spring-mass system, a displacement sensing structure, a displacement detecting circuit, a cavity body and a level adjustment base; the spring-mass system is disposed inside the cavity body and includes: a negative-stiffness spring, a positive-stiffness spring, a proof mass and an outer frame; the proof mass is connected to the outer frame by the negative-stiffness spring and the positive-stiffness spring, the negative-stiffness spring and the positive-stiffness spring are symmetrically disposed with respect to the proof mass, and the outer frame is fixedly connected to the cavity body; the displacement sensing structure is located on a surface of the proof mass, and the displacement detecting circuit is configured to detect a displacement signal from the displacement sensing structure; the spring-mass system realizes reduction in resonant frequency by matching of the positive and negative stiffness springs; and change in gravitational acceleration is detected by detecting a displacement of the proof mass. The MEMS gravimeter has high stability, small size and light weight, and thus can effectively reduce the production cost as well as the development difficulty of the signal detection unit and stable platform.

The present invention discloses a MEMS gravimeter comprising: a spring-mass system, a displacement sensing structure, a displacement detecting circuit, a cavity body and a level adjustment base; the spring-mass system is disposed inside the cavity body and includes: a negative-stiffness spring, a positive-stiffness spring, a proof mass and an outer frame; the proof mass is connected to the outer frame by the negative-stiffness spring and the positive-stiffness spring, the negative-stiffness spring and the positive-stiffness spring are symmetrically disposed with respect to the proof mass, and the outer frame is fixedly connected to the cavity body; the displacement sensing structure is located on a surface of the proof mass, and the displacement detecting circuit is configured to detect a displacement signal from the displacement sensing structure; the spring-mass system realizes reduction in resonant frequency by matching of the positive and negative stiffness springs; and change in gravitational acceleration is detected by detecting a displacement of the proof mass. The MEMS gravimeter has high stability, small size and light weight, and thus can effectively reduce the production cost as well as the development difficulty of the signal detection unit and stable platform.

The present invention discloses a MEMS gravimeter comprising: a spring-mass system, a displacement sensing structure, a displacement detecting circuit, a cavity body and a level adjustment base; the spring-mass system is disposed inside the cavity body and includes: a negative-stiffness spring, a positive-stiffness spring, a proof mass and an outer frame; the proof mass is connected to the outer frame by the negative-stiffness spring and the positive-stiffness spring, the negative-stiffness spring and the positive-stiffness spring are symmetrically disposed with respect to the proof mass, and the outer frame is fixedly connected to the cavity body; the displacement sensing structure is located on a surface of the proof mass, and the displacement detecting circuit is configured to detect a displacement signal from the displacement sensing structure; the spring-mass system realizes reduction in resonant frequency by matching of the positive and negative stiffness springs; and change in gravitational acceleration is detected by detecting a displacement of the proof mass. The MEMS gravimeter has high stability, small size and light weight, and thus can effectively reduce the production cost as well as the development difficulty of the signal detection unit and stable platform.

Disclosed is a detector system for detecting underground anomalies comprising a detector device which includes a fluid chamber which is sealed; a float including a target, positioned within the fluid chamber; and a shielded phase shift proximity sensor configured to detect a distance between the target and proximity sensor, wherein a presence of an underground anomaly is determined based on the detected distance.

Disclosed is a detector system for detecting underground anomalies comprising a detector device which includes a fluid chamber which is sealed; a float including a target, positioned within the fluid chamber; and a shielded phase shift proximity sensor configured to detect a distance between the target and proximity sensor, wherein a presence of an underground anomaly is determined based on the detected distance.

Disclosed is a detector device for detecting the presence of a target substance, the device comprising: a detection rod having a longitudinal rod body, composed of a conductive and non-magnetic material and a support structure configured to support the detection rod at an fulcrum site between a detection end and the counterbalance end of the detection rod. The support structure is configured to sustain the detection rod in a static state absent an external force and to guide a rotation of the detection rod in response to an external force, which may include a force effectuated by the presence of the target substance.

Disclosed is a detector device for detecting the presence of a target substance, the device comprising: a detection rod having a longitudinal rod body, composed of a conductive and non-magnetic material and a support structure configured to support the detection rod at an fulcrum site between a detection end and the counterbalance end of the detection rod. The support structure is configured to sustain the detection rod in a static state absent an external force and to guide a rotation of the detection rod in response to an external force, which may include a force effectuated by the presence of the target substance.

An apparatus and method for measuring a local acceleration of gravity includes releasing a ferrous rod having a regular alternating pattern of reflective and non-reflective portions on a surface thereof from an electromagnetic holder so that the rod falls with a substantially vertical acceleration and substantially no angular velocity about a center of mass of the rod. The falling rod is illuminated with a light emitting diode (LED) configured to emit infrared (IR) light, and IR light emitted by the LED and reflected by the falling rod is detected with a photodiode. A two-state signal is generated corresponding to an illumination state of the photodiode by the reflected IR light. Times of transitions between the two states in the generated signal are calculated to determine kinematic data, and the kinematic data is fitted to a predetermined curve to calculate a local acceleration of gravity.

An apparatus and method for measuring a local acceleration of gravity includes releasing a ferrous rod having a regular alternating pattern of reflective and non-reflective portions on a surface thereof from an electromagnetic holder so that the rod falls with a substantially vertical acceleration and substantially no angular velocity about a center of mass of the rod. The falling rod is illuminated with a light emitting diode (LED) configured to emit infrared (IR) light, and IR light emitted by the LED and reflected by the falling rod is detected with a photodiode. A two-state signal is generated corresponding to an illumination state of the photodiode by the reflected IR light. Times of transitions between the two states in the generated signal are calculated to determine kinematic data, and the kinematic data is fitted to a predetermined curve to calculate a local acceleration of gravity.