The New Worlds Imager is the proposed final stage of New Worlds Mission, a proposal to put up a network of huge large starshades and accompanying telescopes. By using precisely design occulters (starshades), space telescopes could better image planets in other solar systems, many of which are more than a billion times more faint than the stars they orbit. The first starshade could be deployed in front of an already-existing telescope, such as James Webb Space Telescope.
Headed by Dr. Webster Cash of the University of Colorado at Boulder, the New Worlds Imager was funded by the NASA Institute for Advanced Concepts until it was dissolved in 2007.
Exoplanets are so distant and faint that a starshade is practically necessary to image them at all. Another plausible technique is interferometry, which means the collation of data between different telescopes. One of the possibilities of the New Worlds Mission, the New Worlds Imager, would combine together multiple telescopes (interferometry) with the starshade principle. In order of sophistication and cost, the possible missions are:
New Worlds Discoverer - this would include one or two starshades combined with an existing or soon-to-be-launched space telescope. As the name implies, its purpose would be to discovered exoplanets through optical imaging.
New Worlds Observer - this would involve two space telescopes and two starshades to obtain better angular resolution through interferometry.
New Worlds Imager - this, the most sophisticated possibility, would use five space telescopes and starshades for the potential of actual imaging of exoplanet surfaces. With this, you could see green splotches like the Amazon rainforest on planets dozens or hundreds of light years away.
The New Worlds Missions are fascinating, because in the longer term they offer the possibility of actually getting optical images of exoplanets. One can only guess how the public might react to recognizable images of distant planets. If exoplanets in our immediate vicinity have any sort of biospheres, this would likely be observable through the New Worlds Imager.