HIREX
Off-axis Instrument Design
Instrument Overview:
The HIREX instrument consists of several critical component assemblies:
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Tuneable X-Ray Imager (TXI)
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Filter Wheel Assembly
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CCD Cameras
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Focal Plane Drive System
Tuneable X-Ray Imager (TXI):
Several wavelength discrimination techniques were reviewed before a TXI
consisting of a single moving mirror was selected. The mirror has
a narrow band multilayer coating and rotates about the same center that
the CCD camera drive rotates about. The mirror can be moved through 30o
accurately enough to meet the system wavelength selection criteria. For
observations that need more light, do not need a limited wavelength response
or are observing outside the band of the TXI's response, the TXI can be
rotated about a separate axis and be removed from the optical path.
Filter Wheel Assembly:
The filter wheel assembly consists of multiple wheels, each of which holds
4 filters, that permit astronomers to select the desired observing spectrum
and reject the light in undesired wavelengths.
CCD Cameras:
The focal plane consists of 2 separate, identical cameras each consisting
of 3, 2000 by 4000 15micron pixels. The cameras ride on a circular drive
that keeps them in focus and on center as the single mirror TXI moves to
select the desired portion of the spectrum. A heat removal system is attached
to the back to the CCD's.
Focal Plane Drive System:
The location of the focal plane moves with the selection of a given band
pass. To compensate for this the focal plane rotates through an angle of
120o, around the same axis as the TXI, starting on the optical
axis. The motion is accomplished on a rotating stage mounted on the same
axis as the TXI mirror but driven through twice the angle. The focal plane
position is tracked with a flexible Inductosin.
Questions, comments pcheimets@cfa.harvard.edu