The Large Binocular Telescope

Abstract

The Large Binocular Telescope (LBT) Observatory is a collaboration between institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio and Virginia. The telescope on Mt. Graham in Southeastern Arizona uses two 8.4-meter diameter primary mirrors mounted side-by-side to produce a collecting area equivalent to an 11.8-meter circular aperture. A unique feature of LBT is that the light from the two primary mirrors can be combined to produce phased array imaging of an extended field. This coherent imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65-meter telescope. We will describe the scientific results and technical challenges of monocular prime focus imaging starting in Fall 2006. Binocular imaging with two co-pointed prime focus cameras began in Fall 2007. Installation of a rigid (non-adaptive) secondary mirror occurred in Spring 2008 in time for the arrival of the first Gregorian spectrometer. The telescope will use two F/15 adaptive secondaries to correct atmospheric turbulence. The first of these adaptive mirrors is now being tested in Italy, and is planned to be at the telescope by Summer 2009.

Implementation of a laser-truss based telescope metrology system at the Large Binocular Telescope

“…Prime focus has a single focal station operating at F/1.142. The Gregorian and bent Gregorian modes operate at F/15 [2]. Prime focus is engaged for use with the Large Binocular Camera (LBC).…”

“…When the telescope is perfectly collimated the extra-focal image is non-aberrated and looks like then entrance pupil of the telescope. The size, centration of the central obscuration, ellipticity, and ratio of central obscuration size to outer diameter of the extra-focal image can determine focus, coma, astigmatism, and spherical aberration respectively [2]. The traditional technique for using defocused pupil images usually involves intra-focal as well as extra-focal pupil images as shown in Figure 7.…”

Experimental Study of a Multispectral Piston Sensing Technology

“…In a segmented telescope, the primary mirror is created by splicing an array of actuated hexagonal segmented mirrors together, which makes it easier to fabricate than the monolithic mirror of equivalent size in a monolithic mirror telescope. Multi-aperture telescopes have also been widely studied, including the Large Binocular Telescope (LBT) [9], Adaptive Reconnaissance Golay-3 Optical Satellite (ARGOS) [10], and Star-9 [11]. In a multi-aperture system, an array of afocal telescopes is combined to achieve a resolution equivalent to the resolution of a primary mirror with the entire array size.…”

Multi-aperture digital coherent combining for free-space optical communication receivers

“…Another approach for increasing collection area is to combine signals from multiple apertures. The concept of using multiple receive apertures to increase collection area has been successfully demonstrated in radio frequency (RF) systems (e.g., the NASA Deep-Space Network (DSN) [14]) and optical imaging telescopes (e.g., Large Binocular Telescope Observatory (LBTO) [15]). Large monolithic telescope apertures, however, have difficulty pointing near the sun or operating during the day due to thermal heating issues.…”