Measuring Acceleration with Light

<div><div>This animation demonstrates the operating principles of a new accelerometer. This optomechanical accelerometer consists of two silicon chips. The first chip has a proof mass suspended by a set of silicon beams, which allows the proof mass to move vertically. The top of the mass has a mirrored coating. The second chip has an inset hemispherical mirror. Together the mass and hemisphere mirrors form an optical cavity. Infrared laser light is directed into the device. Most frequencies are reflected entirely. However, light matching the resonant frequency builds up inside the cavity, increasing in intensity, until the intensity of the light transmitted by the cavity matches the input. Light transmitted by the cavity can be detected on the other side. When the device accelerates, the length of the cavity changes, shifting the resonant frequency. By continuously matching the laser to the resonant frequency of the cavity, researchers can determine the acceleration of the device. Animation: Sean Kelley/NIST</div><div><br></div></div>