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Science Instruments
High Resolution Camera (HRC)
HRC Illustration
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The High Resolution Camera
(HRC) is one of two instruments used at the focus
of Chandra, where it detects X-rays reflected from an assembly
of eight mirrors. The unique capabilities of the (HRC) stem from the close
match of its imaging capability to the focusing power of the
mirrors. When used with the Chandra mirrors, the (HRC) can make images that
reveal detail as small as one-half an arc second. This is
equivalent to the ability to read a newspaper at a distance of
half a mile.
(HRC)
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The primary components of the (HRC) are two Micro-Channel Plates (MCP). They
each consist of a 10-cm (4-inch) square cluster of 69 million
tiny lead-oxide glass tubes that are about 10 micrometers in
diameter (1/8 the thickness of a human hair) and 1.2 millimeters
(1/20 an inch) long. The tubes have a special coating that
causes electrons to be released when the tubes are struck by
X-rays. These electrons are accelerated down the tube by a high
voltage, releasing more electrons as they bounce off the sides
of the tube. By the time they leave the end of the tube, they
have created a cloud of thirty million electrons. A crossed grid
of wires detects this electronic signal and allows the position
of the original X-ray to be determined with high precision. With
this information astronomers can construct a finely detailed map
of a cosmic X-ray source. The (HRC) is especially useful for imaging hot
matter in remnants of exploded stars, and in distant galaxies
and clusters of galaxies, and for identifying very faint
sources.
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