Laser accelerometer

Laser accelerometer

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A laser accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...

comprises a frame having three orthogonal input axes and multiple proof masses, each proof mass having a predetermined blanking surface. A flexible beam supports each proof mass.

The flexible beam permits movement of the proof mass on the input axis. A laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 light source provides a light ray. The laser source is characterized to have a transverse field characteristic having a central null intensity region. A mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

 transmits a ray of light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

to a detector. The detector is positioned to be centered to the light ray and responds to the transmitted light ray intensity to provide an intensity signal. The intensity signal is characterized to have a magnitude related to the intensity of the transmitted light ray.

The proof mass blanking surface is centrally positioned within and normal to the light ray null intensity region to provide increased blanking of the light ray in response to transverse movement of the mass on the input axis.

The proof mass deflects the flexible beam and moves the blanking surface in a direction transverse to the light ray to partially blank the light beam in response to acceleration in the direction of the input axis. A control responds to the intensity signal to apply a restoring force to restore the proof mass to a central position and provides an output signal proportional to the restoring force.