Nanjing Tianguang Institute completed the processing of Φ2.5 meters aspheric mirror

Recently, the Laboratory of Astronomy and Space Mirror Technology of Nanjing Institute of Astronomical and Optical Technology, National Astronomical Observatory of the Chinese Academy of Sciences, completed the processing of a 2.
5-meter aperture aspheric mirror
.
The mirror is the largest single-aperture mirror developed by Nanjing Institute of Tianguang, and it is also another large-scale aspheric mirror in recent years after the 2-meter circular primary mirror of the Yunnan Astronomical Observatory Solar Telescope and the 1.
6-meter primary mirror of the Yunnan University Multi-channel Telescope
.

In the process of mirror processing, the researchers built an integrated machining/testing platform based on the vertical inspection tower and the original 4-meter gantry machine tool, which can realize in-place detection and solve a number of technical difficulties in large-mirror and long-path optical inspection
.

The mirror is processed by a self-developed dual-robot CNC research and throwing station
.
The mirror numerical control research group of the office has independently carried out relevant technical research for many years, and has played a key role in a
large number of mirror processing tasks undertaken by Nanjing Tianguang in various horizontal and longitudinal topics.
In order to cope with the extra-large mirror surface with a diameter of 2.
5 meters, the research group further developed the two-robot collaborative research and polishing technology and the small-scale error local polishing technology on the basis of the existing technology, which greatly improved the efficiency of the extra-large aperture mirror before, during and after the processing respectively
.
The final surface shape accuracy RMS value of the 2.
5-meter aspheric mirror reaches 1/45 wavelength, that is, 14nm, which is better than the design index of 1/40 wavelength
.
A number of invention patents have been applied for related technologies, one of which has been authorized
.

The completion of this mirror and the earlier 2-meter primary mirror and 1.
6-meter primary mirror marks that Nanjing Tianguang Institute has built a mature large-diameter aspheric mirror development platform, with efficient development capabilities of 2.
5 meters and above mirrors, and the related processing and testing technologies have reached the domestic advanced level
.

2.
5m mirror machining/inspection platform (left) and final machining surface shape stripe diagram (right)