We have developed microshutter array systems at NASA Goddard Space Flight Center for use as multi-object
aperture arrays for a Near-Infrared Spectrometer (NIRSpec) instrument. The instrument will be carried on the
James Webb Space Telescope (JWST), the next generation of space telescope, after the Hubble Space
Telescope retires. The microshutter arrays (MSAs) are designed for the selective transmission of light from
objected galaxies in space with high efficiency and high contrast. Arrays are close-packed silicon nitride
membranes with a pixel size close to 100x200 μm. Individual shutters are patterned with a torsion flexure
permitting shutters to open 90 degrees with minimized stress concentration. In order to enhance optical
contrast, light shields are made on each shutter to prevent light leak. Shutters are actuated magnetically,
latched and addressed electrostatically. The shutter arrays are fabricated using MEMS bulk-micromachining
and packaged utilizing a novel single-sided indium flip-chip bonding technology. The MSA flight system
consists of a mosaic of 2 x 2 format of four fully addressable 365 x 171 arrays. The system will be placed in
the JWST optical path at the focal plane of NIRSpec detectors. MSAs that we fabricated passed a series of
qualification tests for flight capabilities. We are in the process of making final flight-qualified MSA systems
for the JWST mission.
KEYWORDS: Camera shutters, Electrodes, Magnetism, Indium, Silicon, James Webb Space Telescope, Optical fabrication, Metals, Microelectromechanical systems, Space telescopes
A complex MEMS device, microshutter array system, is being developed at NASA Goddard Space Flight
Center for use as an aperture array for a Near-Infrared Spectrometer (NirSpec). The instrument will be
carried on the James Webb Space Telescope (JWST), the next generation of space telescope after Hubble
Space Telescope retires. The microshutter arrays (MSAs) are designed for the selective transmission of light
with high efficiency and high contrast. Arrays are close-packed silicon nitride membranes with a pixel size
close to 100x200 &mgr;m. Individual shutters are patterned with a torsion flexure permitting shutters to open 90
degrees with a minimized mechanical stress concentration. Light shields are made on to each shutter for light
leak prevention so to enhance optical contrast. Shutters are actuated magnetically, latched and addressed
electrostatically. The shutter arrays are fabricated using MEMS bulk-micromachining technologies and
packaged using single-sided indium flip-chip bonding technology. The MSA flight concept consists of a
mosaic of 2 x 2 format of four fully addressable 365 x 171 arrays placed in the JWST optical path at the focal
plane.
KEYWORDS: Camera shutters, Electrodes, Indium, Magnetism, Silicon, James Webb Space Telescope, Optical fabrication, Metals, Microelectromechanical systems, Space telescopes
MEMS microshutter arrays (MSAs) are being developed at NASA Goddard Space Flight Center for use as an aperture
array for the Near-Infrared Spectrometer (NirSpec). The instruments will be carried on the James Webb Space
Telescope (JWST), the next generation of space telescope after Hubble Space Telescope retires. The microshutter arrays
are designed for the selective transmission of light with high efficiency and high contrast. Arrays are close-packed
silicon nitride membranes with a pixel size of 105x204 μm. Individual shutters are patterned with a torsion flexure
permitting shutters to open 90 degrees with a minimized mechanical stress concentration. Light shields are made on each
shutter for light leak prevention to enhance optical contrast. Shutters are actuated magnetically, latched and addressed
electrostatically. The shutter arrays are fabricated using MEMS technologies. Single-side indium flip chip bonding is
performed to attach microshutter arrays to substrates.
KEYWORDS: Camera shutters, Electrodes, Silicon, Metals, Magnetism, James Webb Space Telescope, Optical fabrication, Microelectromechanical systems, Semiconducting wafers, Reactive ion etching
Micro Electromechanical System (MEMS) microshutter arrays are being developed at NASA Goddard Space Flight Center for use as a field selector of the Near Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST). The microshutter arrays are designed for the spontaneous selection of a large number of objects in the sky and the transmission of light to the NIRSpec detector with high contrast. The JWST environment requires cryogenic operation at 35 K. Microshutter arrays are fabricated out of silicon-on-insulator (SOI) silicon wafers. Arrays are close-packed silicon nitride membranes with a pixel size of 100 x 200 μm. Individual shutters are patterned with a torsion flexure permitting shutters to open 90 degrees with a minimized mechanical stress concentration. Light shields are processed for blocking light from gaps between shutters and frames. The mechanical shutter arrays are fabricated using MEMS technologies. The processing includes multi-layer metal depositions, the patterning of magnetic stripes and shutter electrodes, a reactive ion etching (RIE) to form shutters out of the nitride membrane, an anisotropic back-etch for wafer thinning, followed by a deep RIE (DRIE) back-etch to form mechanical supporting grids and release shutters from the silicon substrate. An additional metal deposition is used to form back electrodes. Shutters are actuated by a magnetic force and latched using an electrostatic force. Optical tests, addressing tests, and life tests are conducted to evaluate the performance and the reliability of microshutter arrays.
KEYWORDS: Energy transfer, Multimode fibers, Reflectivity, Energy efficiency, Tolerancing, Reliability, Signal attenuation, Reflection, Geometrical optics, Single mode fibers
This paper describes an investigation into the development of a LIGA optical energy interrupter for use in a MEMS-based Safety and Arming (S&A) system. The energy interrupter acts as a switch to selectively couple optical power between input and output fiber optic waveguides using either a reflectance or direct coupling technique. This device is a critical component of the S&A system, which must perform its task in a zero-tolerance manner to ensure reliable and safe operation of naval ordnance. The union of fiber optic components with LIGA-based MEMS structures allows development of an energy interruption junction that will isolate the low and high voltage sections of an optical charging circuit. A movable LIGA barrier interacts with optical fibers in order to align or misalign the optical propagation path between the source and receiver in the circuit. The implementation of such a design allows for the `Safe' operational mode of an S&A system with the optic path broken, and an `Arm' mode during energy transfer. Effects such as fiber misalignment, light scattering, and multiple reflections are sources of potential failure modes for this micromachined optical system. This paper is concerned with the effects of fiber misalignment of system reliability. Three primary fiber/barrier topologies are discussed. Computer simulations used to establish the positioning and geometric tolerances in the MEMS structure to ensure maximum functional reliability are described, and experimental results are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.