MEMS: micro-electromechanical system

The baseline design for the NGST Near-IR Spectrograph (NIRSpec) uses a micro-electromechanical system, consisting of an array of about 1000x500 micro-shutters, to select hundreds of different objects in a single field of view.

This is a scanning microscope image of the micro-shutters, under development at Goddard Space Flight Center (Principle Investigator: Harvey Moseley). The shutters are 100 microns center-to-center and about 90 microns wide. For NIRSpec 100x200 micron (spectral x spatial direction) shutters will be used. All shutters are slightly magnetized and are opened by scanning a permanent magnet over the array. Selected apertures are held open electrostatically, by applying a voltage difference between the shutter and an electrode on the wall. After the magnet has passed by, the resilience of the hinges flips the remaining shutters closed. (Note that these shutters, unlike the flight devices, do not have shields to prevent light from passing around the edges)

Microshutters are a new piece of technology being used on the Near Infrared Spectrograph (NIRSpec) instrument on JWST. NIRSpec is an instrument that will allow scientists to capture the spectra of more than 100 objects at once. Because the objects NIRSpec will be looking at are so far away and so faint, the instrument needs a way to block out the light of nearer bright objects. The microshutters were developed to help solve this problem. Micro shutters are tiny cells that measure 100 by 200 microns, or about the width of three to six human hairs. The Goddard JWST Site has more information on the microshutter arrays.