INO 340


The Optics

The telescope is a Ritchey-Chrétien f/11 which provides unvignetted 20 arcmin filed of view at the main Cassegrain focus. In addition 3 bended focus are also provided each with a field of view of 8 arcmin.

The main mirror (M1) is single segment fast f/1.5 mirror with a diameter of 3.4m, which makes IN340 one of the most compact telescopes at this size. M1 is a meniscus shape 18 cm thick made of a Zerudor ceramic with a 700mm central hole. The M1 is polished to 1nm roughness. The M1 is supported by 60 actuators which are actively or passively controlled to keep the mirror shape undistorted under its own gravity at different pointing.


The 600mm secondary mirror reflects the light from the primary mirror and is also controlled by a hexapod. The mirror has is made of a Zerodur ceramic and has a hyperbolic surface geometry.

The structure

The telescope mount is altitude over azimuth (alt-az) which allows the telescope to be very compact (relatively speaking) and provides direct load paths from the telescope down through the structure to the pier and foundations.

The drive motors used to move the telescope in azimuth and elevation will be servo motors with position feedback will be provided by linear tape encoders.

Telescope Control System (TCS)

The TCS is responsible for controlling a number of subsystems, such as the mount control system (MCS) which is responsible for pointing and tracking the targets and the mirrors control system or active control systems (ACS). MCS receives commands from the user interface.