HIPPARCOS Collimator

This collimator is made of a parabolic mirror with a focal length of 2800 mm and a diameter equal to 350 mm.

The wavefront error is lower than l/50 at 550 nm.
The body of the collimator is a cylinder made of invar, supported by two XY motorized systems at each extremity.
rnThese XY systems are controlled by micro-processor and allow, byrncombining their movements, to move the optical axis inside a 2° conernwith an accuracy equal to 1 arcsecond. The stability of the structurernwas a major parameter. The optical axis has a stability with respect tornthe base structure better than 1 milliarcseconds.

Thisrncollimator is certified to work under 10-6 mbar vacuum. It wasrndevelopped to meet the specifications of CSL and MATRA for thernalignment of the HIPPARCOS (HIgh Precision PARallax COllectingrnSatellite) payload.

[2007-04-06]