Large Telescope metrology

High precision metrology systems for dimensional control of large telescopes

segmented mirrors positioning
focus adjustment for primary mirror
tip-tilt control of adaptative optics & image stabilizer
delay line rails & Coudé rotating platforms control

Main features

FOGALE metrology solutions for large telescopes allow high precision dimensional control of key elements for an optimal operation of the telescope during its lifespan:

segmented mirror positioning: tip, tilt, piston, gap and DGRoC measurement
primary mirror focus and CoC positioning: optical ranging measurement
adaptive optics & image stabilizer positioning: tip-tilt control
delay line rail and Coudé rotating platform: levelling and alignment

These systems are qualified on the field on several large telescopes.

Key benefits

Edge sensors systems for segmented mirrors makes use of a patented innovative design, allowing unique features:

Nanometer resolution
Not sensitive to environment: Edge sensors are not sensitive to humidity and pollution (dust) and offer a very high rejection of condensation, temperature, and electronic perturbations.
High rejection of gap and tilt variations

Optical ranging measurement solution for primary mirror focus adjustment allows absolute distance measurements offering excellent accuracies at high distances (+/-10 microns at 20m). It is based on LENSCAN metrology solution, which also allows all optical elements positioning with sub-micron accuracy.

Tip-tilt control systems for adaptive optics are based on non-contact magnetic actuators offering a very high resolution (<0.05 arc second) and a bandwidth up to 100Hz.

Levelling & alignment systems for Coudé rotating platform and long delay line rails is based on HLS (Hydrostatic Levelling System) and WPS (Wire Positioning System) that allow high accuracy micrometer range levelling and alignment within large distances.