The James Webb Space Telescope (JWST) has successfully demonstrated its ability to maintain an extraordinary level of optical precision in its mirror alignment, a critical factor for capturing clear images of the universe.
Unlike its predecessor, the Hubble Space Telescope, JWST utilizes a primary mirror composed of 18 hexagonal segments, each measuring 1.3 meters wide. This innovative design allows the telescope to fit into a launch rocket and unfold in space, effectively functioning as a single 6.5-meter mirror.
To achieve and maintain precise alignment, each mirror segment is equipped with actuators that enable adjustments along six axes. The alignment process employs a wavefront phase technique, where the interference patterns of overlapping light waves are analyzed. The telescope's Near Infrared Camera (NIRCam) plays a pivotal role in this process by capturing images of stars and allowing the team to realign the mirrors as needed.
Since its launch, the JWST team has conducted regular wavefront error checks, typically every other day, to counteract minor shifts caused by vibrations and temperature changes. Remarkably, while the design goal for wavefront error was set at 150 nanometers, the team has consistently achieved an impressive 65 nanometer error margin, enabling the telescope to produce breathtaking images of distant galaxies.