Engineering topics

Ge, Jian

Publications and source records attributed to Ge, Jian.

4 records

NASA NTRS2006

A Nulling Coronagraph for TPF-C

The nulling coronagraph is one of 5 instrument concepts selected by NASA for study for potential use in the TPF-C mission. This concept for extreme starlight suppression has two major components, a nulling interferometer to suppress the starlight to ~10(sup -10) per airy spot within 2 (lamda)/D of the star, and a calibration interferometer to measure the residual scattered starlight. The ability to work at 2 (lamda)/D dramatically improves the science throughput of a space based coronagraph like TPF-C. The calibration interferometer is an equally important part of the starlight suppression system. It measures the measures the wavefront of the scattered starlight with very high SNR, to 0.05nm in less than 5 minutes on a 5mag star. In addition, the post coronagraph wavefront sensor will be used to measure the residual scattered light after the coronagraph and subtract it in post processing to 1~2x10(sup -11) to enable detection of an Earthlike planet with a SNR of 5~10.

Terrestrial Planet Finder Coronagraph (TPF-C)↗

NASA NTRS2005

Transmissive Microshutter Array Technology Development Program

This is a one-year program starting on April 15,2003 to develop two infrared silicon grism for Rapid Visible and Infrared Multiple Object Spectrometer (RIVMOS) for observations in 1.1 - 5 microns.

Ge, Jian↗

NASA NTRS2002

Penn State Activities in the NASA GSFC Transmissive Microshutter Array Technology Development Program

This is a one year contract starting on April 1, 2001 to design the Rapid Infrared and Visible Multiple Object Spectrometer (RIVMOS) and its auxiliary dispersing elements, design and fabricate silicon grisms, and reduce testing data with silicon grisms. Here I report our progress made during the funding period.

Ge, Jian↗

NASA NTRS2001

Microshutter Array Development for the Multi-Object Spectrograph for the New Generation Space Telescope, and Its Ground-based Demonstrator

The 6.5-m NASA/ESA/Canada New Generation Space Telescope to be operated at the L2 Lagrangian point will require a multi-object spectrograph (MOS) operating from 1 to 5 microns. Up to 3000 targets will be selected for simultaneous spectroscopy using a programmable cryogenic (approx. 35K) aperture array, consisting of a mosaic of arrays of micromirrors or microshutters. We describe the current status of the GSFC microshutter array development. The 100 micron square shutters are opened magnetically and latched open or closed electrostatically. Selection will be by two crossed one-dimensional addressing circuits. We will demonstrate the use of a 512 x 512 unit array on a ground-based IR MOS which will cover 0.6 to 5 microns, and operate rapidly to include spectroscopy of gamma ray burst afterglows.

Woodgate, Bruce E.↗