Accelerometers are microelectronic devices as discussed in this blog earlier that are commonly used in mobile phones, air bags and cameras. These are mechanical devices that measure piezoelectric, piezoresistive or capacitative based sensors that measure movement of a small weight. However, there is new technology available that uses lasers to measure movement.
These are called Optical Accelerometers. They are extremely sensitive to acceleration that is at least a 100 fold more sensitive than the microelectronic devices. They are much more resistant to the change in temperature as compared to micro-electronic devices since there is lower percentage of mechanical component.
These optoelectronic devices use lasers which can detect very small range of motion. They are constructed such that they can measure the change in a small mass in the accelerometer through interference or reflection. Interestingly, in some devices the mass is so small that is effectively damped by light which is an advantage at that small distance since it serves to dampen the Brownian motion. Thus, these would be less affected by change in room temperature, which would normally have affected the Brownian motion. Cool the device down further and it makes it extremely sensitive to a change in acceleration not possible before.
Optical accelerometers have started to arrive in different configurations using Fiber Bragg Grating sensors or complex effects like the optical spring effect but CalTech has mode some interesting developments in this field. Read more about them at the link below.