SPINOR construction is in two phases, 'Demonstration' , and 'Deployment'. In the Demonstration phase the ASP control system is maintained and SPINOR cameras made to look like the current ASP bert and ernie computers. In the Deployment phase all ASP computers (except the embedded Mechanism Control Computer) are replaced by new SPINOR computers. Control of the cameras and Polarimeter Control will be via the overall DST experiment control system. The SPINOR computers will all be rack mounted industrial PCs with Pentium 4 processors. The Polarimeter Control computer will have six PCI slots, the Camera Computers need fewer.
For 'visible' observations, 400nm to 1000nm (or so), SPINOR will use a Sarnoff CAM1M100 1024 x 512 pixel, thinned back illuminated, 100 frame per second cameras. This camera uses a Coreco CameraLink interface board and requires two cables. There is also a serial interface cable for camera set up.
Other high speed cameras, provided they adhere to the DST
Virtual Camera standard, could also be used. For example PixelVision
Pluto or BioXight 652x488 cameras would work quite well, though with a smaller
field of view.
Virtual cameras accept commands from the DST to produce images that are
typically derived from many individual CCD reads. In the case of SPINOR,
the virtual cameras will provide 'Stokes' images made from n x 8 frames (in the
case of a rotating retarder). These images will be three dimensional,
spectral, spatial, and polarimetric (I, Q, U, and V). These cameras need
to have frames strobed, so each accepts an external TTL strobe line. The
computer in the virtual camera needs to know the phase of the polarization
modulator, so each reads the modulator position on its parallel (printer) port.
The camera computers are rack mount industrial chassis with ATX mother boards and
P4 processors. Computers are relatively fast for their time in order to
handle the tremendous data rate from these cameras. There local disk
storage a SAN interface (either direct or via Ethernet ) for when the computer
has time to off load the data.
For the Infrared, SPINOR uses a Rockwell TCM 8600 1k X 1k pixel HgCdTe hybrid
cameras. This camera was originally purchased for the HAO Coronal
Magnetic field Project (COMP) with the provision that it would be available
from time to time to other HAO programs. This camera uses a National Instruments
IMAQ CameraLink interface. It
accepts an external strobe to trigger frame reads.
Polarimeter optics are positioned via the Polarimeter Control Computer. It receives commands via TCP/IP and relays them to the old ASP Mechanism Control computer via RS-232. The other function is control of the polarimeter timing, rotation of the modulator, sending strobes to the cameras, and sending modulator position information to the virtual camera computers. Modulator position is controlled using a Galil 1840 Motion Controller.
The ASP rotating retarder polarization modulator uses an unmaintainable Baldwin encoder. For instrument reliability, the modulator drive motor, encoder, and driver are replaced. Modulator position is controlled using a Galil 1840 Motion Controller.