From Encyclopedia Jr, free information reference for Kids
A gravimeter is a device designed to measure the local gravitational field. Also sometimes called a gravitometer, a gravimeter is a type of accelerometer. According to the equivalence principle of Albert Einstein, the effects of a gravitational field are rigorously equivalent to acceleration. Therefore, gravimeters are susceptible to vibration which causes small, oscillatory accelerations. This is counteracted by integral vibration isolation and signal processing.
Though the essential principle of design is the same as accelerometers, gravimeters are typically much more sensitive than accelerometers in order to measure very tiny changes within the earth's gravity of 1 g (see unit gee). In contrast, accelerometers are often designed to measure 1000 g or more, and many perform multi-axial measurements. The constraints on temporal resolution are usually less for gravimeters, so that resolution can be increased by processing the output with a longer "time constant".
The field of gravimetry deals with measuring gravitational fields. A high-grade, calibrated gravitometer such as the portable LaCoste-Romberg gravimeter can measure the earth's gravitational field to within 1 μ-gal, or 1 ng (10-9 g's). Measurements of the surface gravity of the earth are part of geophysical analysis. (For an image of earth's gravity shape, see gravity).
There has also been some interest in the use of gravimeters to detect possible changes in the gravitational field in various anti-gravity experiments.