JWST Optical Simulation Testbed (JOST)

The JWST Optical Simulation Testbed (JOST) is a tabletop experiment to simulate the main aspects of wavefront sensing and control (WFS&C) for a segmented space telescope, including both commissioning and maintenance. JOST has an optical design using three aspheric lenses that reproduces the physics of JWST's three-mirror anastigmat. A segmented deformable mirror stands in for the segmented primary. The optical system provides equivalent sampling and image quality as a JWST NIRCam module, but at HeNe wavelength. With 59 degrees of freedom, we can implement many commissioning activities such as phase retrieval algorithm validation studies with a hexagonally segmented DM, test validation of pupil imaging lens concepts and designs, investigate field-dependence (multiple field point sensing and control), test wavefront control software, and train and develop staff expertise.

JOST Assembled Testbed [PDF]
JOST Testbed and Results, SPIE [ADS link]
JOST design of a three-lens anastigmat telescope simulator, SPIE [ADS link]

JWST Optical Simulation Testbed poster [PDF]

High-contract imager for Complex Aperture Telescopes (HiCAT)

This project seeks to develop high contrast coronagraphic techniques for segmented telescopes, providing an integrated solution for wavefront control and starlight suppression on complex aperture geometries. Developing this technology will enable direct imaging of exoplanets from space with significant cost savings relative to monolithic mirrors.

HiCAT APLC/shaped-pupil hybrid coronagraph designs, AAS [ADS link]

HiCAT Design overview and first light results, SPIE [ADS link]
HiCAT testbed design and coronagraph developments, AAS [ADS link]

High-Contract Imaging with Segmented Apertures poster [PDF]

Non-Redundant Aperture Masking Interferometry

Study high-contrast with NRMs for segmented telescopes, and WFS&C strategies.

Non-Redundant Aperture Masking Interferometry poster [PDF]

Polarimetry Experiment for Zodi (PEZ)

The Polarimetry Experiment for Zodi (PEZ) is an imaging polarimeter designed to measure the polarization of sunlight scattered by zodiacal dust particles within 1 AU of the Sun.  The instrument uses a new technology where wire grids are bonded directly to the pixels on the CCD.  Clusters of four pixels have wire grids that are oriented 45 degrees from each other, and form a ³superpixel² or ³polarpixel.² This enables the linear Stokes parameters to be obtained in a single exposure without the
need for any moving parts. Such micropolarizer arrays enable the fabrication of instruments that do not require moving parts and are much smaller than has been possible before.  PEZ uses such a device.  PEZ will be deployed on a Boeing 737-800 to obtain images of the zodiacal light (Zodi) during the total solar eclipse of 2015. This will primarily be a test-of-concept exercise, and will form the basis for a more advance system that could be deployed on a balloon or high-altitude drone.  This
technology will also provide a pathway for possible future deployment of micropolarizer arrays on future space telescope missions

Polarimetry Experiment for Zodi poster [PDF]

STScI Polarimetry Testbed

The Polarimetry Test Bed (PTB) is an assembly for testing polarimetry optics and instruments.  It consists of a NIST-calibrated light source that feeds an integrating sphere.  The output of the integrating sphere is fed to a chain of optics that will illuminate the test piece.  The optics train can supply:
  • unpolarized light, using a combination of one or more optics including an opal diffuser, a depolarizer and barium sulfate diffuser.
  • Polarized light using a Glan-Thompson prism with extinction „ 10^5
  • Analyzed polarized light with a Wollaston prism
  • Rotation of the polarized signal either using a half-waveplate or by rotating the Glan-Thompson prism
  • Circular polarization can also be supplied by introducing a quarter-waveplate

PTB PolarCam [png]

Future Experiments

Digital Micromirrors for Multi Object Spectroscopy

Digital Micromirrors for Multi Object Spectroscopy poster [PDF]