HIREX

On-axis Instrument Design

Instrument Overview:

The HIREX instrument consists of several critical component assemblies:

Tuneable X-Ray Imager (TXI):

The HIREX TXI consists of a single mirror with a narrow band multilayer coating that rotates about the same center that the CCD camera drive rotates about. The mirror can be 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:

Several wavelength discrimination techniques were reviewed before a TXI consisting of a single moving mirror was selected. This technique has many advantages but it requires the focal plane to move to a different location for each spectral band. To meet the requirements the focal plane rotates 120o, about the same axis as the TXI, starting on the optical axis. The motion is accomplished on a round recirculating ball bearing track. The focal plane is attached to 2 carts that in turn ride on precision ground arc segments. An onboard motor engages as a circular rack, while the focal plane position is tracked with a flexible Inductosin.
Questions, comments pcheimets@cfa.harvard.edu