Instrument Support Boxes

 
   
3D Rendering of the IR-ISB fully populated with instruments. Phoenix is the gold cylinder mounted on the straight-through port, OSIRIS the silver cylinder at the bottom, and Spartan is the grey ribbed box at the top
Instruments are integrated with the ISB off telescope, then the whole instrument package is lifted into place with the facility crane. The image above shows the Optical ISB, with the Goodman Spectrograph installed, being maneuvered in to place at the Optical-Side Nasmyth Focus.

The Nasmyth Instrument Support Boxes (ISB's) can each carry a cluster of three instruments, one in a straight through position, and two on side ports. The box is surrounded by a cage which serves to transfer part of the load from the Namsyth rottaor to an outer bearing, and also drives the Nasmyth cable wrap. Each instrument package includeing the cage and ISB weighst 3000kg.

The cages and boxes, like the the SOAR telescope mount, were fabricated by Vertex-RSI. The various internal mechanism of each ISB are being fabricated and integrated into the boxes at CTIO.

The mechanisms in each ISB include:

  • A facility calibration unit containing both continuum sources for flat fielding, and line sources for wavelength calibration.
  • A linear stage carrying a calibration mirror which is moved into the beam in order to direct light from the calibration unit to the instruments, and removed from the beam to observe. When in the beam a second mirror reflects the light from the telescope towards a port where a filed acquisition camera can be mounted. The same stage also carries a laser projector used for alignemnt and flexure testing of the instruments.
  • Beam steering optics used to direct the light from the telescope to the instrument in use
    • In the case of the IR-ISB a pair of dichroic mirrors are used. One or other of the dichroics is inserted to send the IR light towards the corresponding side port, while transmitting optical light to the guider. With both dichroics removed, both the optical and IR light continue to the straight through port.
    • In the optical ISB a small mirror can be inserted to send light from part of the field towards the side port mounted instrument, or removed to allow it to pass to the straight through port. In this case the guider works arround theperiphery of the science field.
  • A pick off mirror mounted on an X-Y stage which forms the first element of a periscope which delivers the light from a small section of the field to a fast read out guide CCD based guide camera mounted at a fixed position outside the ISB. The guide probe can be moved over a 9x9 arcminute patrol field.