A document discusses a sensor made from off-the-shelf electro-optical photo-diodes and electronics that achieves 20 nm/(Hz)1/2 displacement sensitivity at 1 mHz. This innovation was created using a fiber-coupled laser diode (or Nd:YAG) through a collimator and an aperture as the illumination source. Together with a germanium quad photodiode, the above-mentioned displacement sensor sensitivities have been achieved. This system was designed to aid the Laser Interferometer Space Antenna (LISA) with microthruster tests and to be a backup sensor for monitoring the relative position between a proof mass and a spacecraft for drag-free navigation. The optical displacement sensor can be used to monitor any small displacement from a remote location with minimal invasion on the system.

This work was done by Alexander Abramovici, Meng P. Chiao, and Frank G. Dekens of Caltech for NASA’s Jet Propulsion Laboratory. NPO-30681


Photonics Tech Briefs Magazine

This article first appeared in the January, 2008 issue of Photonics Tech Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.