STRAP Tip-Tilt Control System

STRAP is a complete adaptive optics sensor and real time compensator for tip-tilt correction.
It is based on very high sensitivity, low dark-counts Single Photon Avalanche Photo Diodes(SPADs) that allows efficient adaptive optics tip-tilt correction with faint Natural Guide Stars. Excellent linearity at high flux rate is obtained though the patented Active Quenching Circuits developed by Prof. Cova at Politecnico di Milano.

The custom-developed DSP-VME module embeds all functions required by a tip-tilt stabilization system:

  • counting units, Real Time digital control and diagnostic (performed on a DSP unit)
  • digital and analog control of the steering mirror
  • high voltage bias generation for APDs
  • controller for APDs’ Peltier thermocooler

STRAP is fully compatible with typical VME control environments (VxWorks drivers available). It is also possible to operate the system through a simple RS232 serial interface.

More than 30 units have been already delivered to E.S.O. (for VLT UTs and ATs), Keck Observatory and Gemini North.