[Music Throughout]
The Wide Field Instrument is the heart of WFIRST.
It is what allows WFIRST to take pictures with the same detail as Hubble,
but covering an area 100 times larger. Despite
this incredible power, the basic design is the same as telescopes around
the world. Light enters through WFIRST's 2.4-meter aperture
and is reflected and focused by the curved main mirror, which is
also the largest mirror in the telescope. This light is reflected
and focused once more by the secondary mirror. Additional elements tighten
the beam even more and strip it of stray light rays before it passes through
the filter wheel. This wheel has a variety of filters that allow
different wavelengths of light to pass through. It spins from one to another
depending on what the researcher is looking for. Finally, the
focused and filtered light reaches the focal plane, where it creates an image on the detectors.
These detectors use the photoelectric effect to convert photons
into an electrical signal that is then then decoded into an image.
In WFIRST's case, there are 18 detectors, allowing it to create
300-million-pixel images of large patches of the sky.
The large number of detectors and pixels gives WFIRST
its wide field of view. The size of the mirror and the precision of its optics
gives WFIRST its fine imaging. This
combination of image size and detail has never been possible on a space-based
telescope before and will make WFIRST an indispensable tool in
the future.
[Explore: Solar System & Beyond]
[NASA]