Magic mirrors:
making the
atmosphere
disappear

The adaptive secondary mirror surface can reshape 1,000 times per second using the world’s most advanced wavefront sensors and algorithms to correct for the optical blurring effect of Earth’s atmosphere.

Adaptive secondary mirrors have a glass-like Zerodur surface that is flexible because of its 1.05 meter diameter and 2 millimeter thickness.

To control the shape of the adaptive secondary mirror, 675 magnets are bonded to the back of the mirror that are pushed or pulled on by electromagnetic actuators.

The 150 micron (thickness of 3 human hairs) air gap between the mirror surface and its frame is used to form a capacitive sensor to help measure its alignment and adjust how the mirror’s surface must adapt to incoming light.

Each adaptive secondary mirror is paired and aligned with only one of the giant seven primary mirrors and is responsible for receiving the distorted light reflected from this primary mirror.