CWS Optomechanics

CWS flight unit (cover removed)
CWS flight unit, mounted in PFI
CWS CMOS camera

KIS is developing for the Sunrise telescope a device for image stabilization and fine guiding in combination with a wave-front sensor that will allow for automatic focussing and telescope alignment during the flight (Correlating wave-front sensor, CWS). The wave-front sensor is based on the adaptive optics systems that have been developed for the solar telescopes on Tenerife. It uses a Shack-Hartmann sensor with 6 sub-apertures for the measurement of tip-tilt, defocus, and coma. These aberrations are corrected by moving the secondary mirror of the telescope. The image stabilization has a sensitivity of 0.005 arcs and a closed-loop bandwidth of 55 Hz.

CWS Optomechanical Design

Wave-front sensor:

The components of the wave-front sensor are mounted on an ultra-lightweight carbon-fiber sandwich plate with a thickness of 30 mm and a length of about 850 mm. The instrument will be conneced to the instrument platform of Sunrise via three isostatic mounts. The main components of the wave-front sensor are:

  • motorized stage at the entrance focal plane , choice between open,  shutter, or pin hole;
  • motorized neutral density wedge for adjustment of the light level;
  • array of microlenses (lenslets) at the pupil image plane;
  • a pair of collimating and imaging lenses;
  • a high-speed CMOS camera.

Tip-tilt mirror:

The tip-tilt unit is part of the image stabilization servo system and has been developed by KIS. The core part of this unit is a commercial piezo stage with a range of +/- 5 mrad (for Sunrise, this corresponds to +/- 50 arcs on the sky).

F2 unit:

A motorized filter wheel is located at the main focal plane of the telescope (F2). The wheel has three fieldstops that can be introduced into the light beam: open field (default), closed, pin-hole.