|
Optical systems used in aerospace applications are often subject to random vibrations. These random motions cause optical elements to shift position, leading to image registration errors, and lower image resolution. Quantifying the impact of these vibrations is key to validating the design, and time is a new factor to consider. The sensor integration time draws a line between slow (drift) and fast (jitter) pointing errors. Distinct methods are introduced to assess the impact of drift and jitter. Besides, if traditional tolerancing tools can be used to model independent elements displacements, this approach is not applicable in the context of vibration analysis. First, the interdependency of each displacement is missed. Then, neither the actual surface deformations due to mechanical stress, nor the potential heating are considered. To successfully solve all these challenges, we propose a new Multiphysics drift and jitter analysis workflow to assess the performance impacts in optical systems using finite elements analysis (FEA) results, from tools like Ansys Mechanical. The behavior of the whole opto-mechanical assembly can then be considered, and the resulting effects of vibration imported back into Ansys Zemax OpticStudio using the STAR tools. Both structural data (surface deformations, rigid body motions) and thermal data (temperature gradient, automatically converted into a gradient index) are used to update the nominal design and compute the impact on the optical performance metrics. New tools have been developed to easily consider series of these datasets, to fully understand vibration impacts and their time dependence. The new insights gained from this new workflow will help taking enlightened decisions for the optical system design as well as its packaging to achieve better performances on system level, in challenging conditions.
|
