Analysis of deforming a 1.5-m ultrathin spherical mirror into an off-axis parabola

Abstract

The collimating mirror is a key component of a solar simulator. It is generally made up of one large spherical or aspherical mirror or some small unit mirrors. By using active optical technology, a spherical mirror can be deformed into an off-axis parabola. This paper reports a finite element analysis process with a 1.5-m ultra-thin spherical mirror. The best fitting spherical surface, active control method, actuator arrangements are introduced respectively. The analysis results show that the surface quality(=2.258 μm RMS) with an arrangement of 21 actuators meets the accuracy requirement, and the maximum stress(=0.979MPa) is less than allowable stress(=3.43 MPa). Finally, 1.5-m prototype mirror and its active support structure are presented. This method is effective for non-imaging optical systems with low precision.