Thermal-stress control of microshutter arrays in cryogenic applications for the James Webb Space Telescope

Daniel P. Kelly; Wen-Hsien Chuang; Larry Hess; Ron Hu; Murzy Jhabvala; Todd King; Mary J. Li; James Loughlin; S. Harvey Moseley; Christopher Ray; Yun Zheng

doi:10.1117/12.608754

1 July 2005 Thermal-stress control of microshutter arrays in cryogenic applications for the James Webb Space Telescope

Daniel P. Kelly, Wen-Hsien Chuang, Larry Hess, Ron Hu, Murzy Jhabvala, Todd King, Mary J. Li, James Loughlin, S. Harvey Moseley, Christopher Ray, Yun Zheng

Author Affiliations +

Proceedings Volume 5836, Smart Sensors, Actuators, and MEMS II; (2005) https://doi.org/10.1117/12.608754
Event: Microtechnologies for the New Millennium 2005, 2005, Sevilla, Spain

Abstract

We report on methods to minimize thermally-induced deformation in a MEMS-based reconfigurable aperture. The device is an enabling component of the Near-Infrared Spectrometer, a principle instrument on NASA’s James Webb Space Telescope. The Microshutter Array consists of 384x175 individually addressable shutters which can be magnetically rotated 90° into the plane of the array and electrostatically latched open. Each shutter is a 100x200 μm rectangular membrane suspended by a small neck region and torsion flexure. The primary materials in the shutter are a 5000Å Si3N4 layer for mechanical rigidity, 2000Å Al for opacity and electrostatic latching, and 2200Å Co90Fe10 for magnetic actuation. This multi-layer stack presents a challenge due to the operating temperatures required for the device: both room temperature (300K) and cryogenic temperature (30K). Thermal expansion of the materials causes the shutters to bow out of plane excessively, which can prevent actuation of the shutters, cause damage to portions of the array, and allow light leakage around closed shutters. Here we present our investigation of several methods to prevent microshutter bowing including deposition of additional materials on the shutters to create a symmetrical layer stack and replacing the current stack with low-coefficient of thermal expansion materials. Using shutter-size suspended cantilever beams as a rapid-development test bed, we have reduced out-of-plane bowing between 300K and 30K to 10% or better. We are currently applying these results to microshutter arrays to develop shutters that remain flat from room temperature to cryogenic temperature while retaining the required mechanical, optical, and magnetic properties.

Citation Download Citation

Daniel P. Kelly, Wen-Hsien Chuang, Larry Hess, Ron Hu, Murzy Jhabvala, Todd King, Mary J. Li, James Loughlin, S. Harvey Moseley, Christopher Ray, and Yun Zheng "Thermal-stress control of microshutter arrays in cryogenic applications for the James Webb Space Telescope", Proc. SPIE 5836, Smart Sensors, Actuators, and MEMS II, (1 July 2005); https://doi.org/10.1117/12.608754

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

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.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
8 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Camera shutters

Electrodes

Metals

Silicon

Cryogenics

James Webb Space Telescope

Aluminum

Show All Keywords

Keywords/Phrases

Search In:

Publication Years