Computationally efficient performance simulations for a thirty-meter telescope (TMT) point design

Abstract

Modeling extremely large ground based optical telescopes is growing in complexity as the level of design detail is increasing. Our model of a 30m telescope includes a modal system of differential equations that represent the telescope structure, an edge controller to monitor and correct the gaps between mirrors of the hexagonally segmented primary mirror, an optical engine that propagates light through the telescope and calculates performance metrics at the exit pupil of the telescope, and a course optical control that can correct the wavefront for tip and tilt. Simulating one minute of telescope observing time with wind and atmospheric disturbances is a computationally intense proposition. The software tools in our arsenal include MATLAB (The MathWorks, Inc.) and OSLO (Lambda Research Corporation). Descriptions of the simulation components, and the results of telescope simulations are presented.

Modeling tools to estimate the performance of the Thirty Meter Telescope: an integrated approach

“…The simulation tools are capable of running on a cluster of Linux computers (Figure 4), as well as on Windows. The details of the realization are discussed elsewhere [2][3][4][5] It may be necessary to run the integrated simulations many times for high-level trade studies, to adequately explore the parameter space. A parametric, frequency domain version of the modeling tool set can highly improve the speed of calculations.…”

“…The telescope surface pressure data provided by CFD were converted to forces acting on the telescope structure and primary mirror [3]. The pressure given on the CFD grid was re-sampled on the structural node grid, forces were calculated by assigning appropriate surfaces to the nodes, and the forces then applied to the corresponding nodes.…”

“…The optical module can feature four different optical kernels: Ray tracing in OSLO, with up to 1000 by 1000 rays resolution, which translates to 3 cm resolution [3,4]; Ray tracing in Zemax, with up to 256 by 256 rays resolution [15]; Full linear optical model linking the exit pupil OPD grid to the displacements of telescope nodes [15];…”

“…The communication with MATLAB, also running on Linux, is facilitated by sockets. The socket communication enables fast transfer of large amounts of data, like complete OPD maps, from OSLO to MATLAB [3]. OSLO also supports the linking of C language routines containing the user defined surfaces and custom ray traces.…”