The development of integrated optomechanical analysis tools has increased significantly over the past decade to address the ever-increasing challenges in optical system design, leveraging advances in computational capability. This book presents not only finite element modeling techniques specific to optical systems but also methods to integrate the thermal and structural response quantities into the optical model for detailed performance predictions.
This edition updates and expands the content in the original SPIE Tutorial Text to include new illustrations and examples, as well as chapters about structural dynamics, mechanical stress, superelements, and the integrated optomechanical analysis of a telescope and a lens assembly.
Optomechanical engineering is the application of mechanical engineering principles to design, fabricate, assemble, test, and deploy an optical system that meets performance requirements in the service environment. The challenge of optomechanical engineering lies in preserving the position, shape, and optical properties of the optical elements with specified tolerances typically measured in microns, microradians, and fractions of a wavelength.
Optomechanical analyses are an integral part of the optomechanical engineering discipline to simulate the mechanical behavior and performance of the optical system. These analyses include a broad range of thermal, structural, and mechanical analyses that support the design of optical mounts, metering structures, mechanisms, test fixtures, and more. This includes predicting the performance, dimensional stability, and structural integrity of optomechanical designs subject to internal mechanical loads and often harsh environmental disturbance, including inertial, pressure, thermal, and dynamic disturbance. Designs must provide for positive margin against failure modes that include yielding, buckling, ultimate failure, fatigue, and fracture.
Analysis starts with first-order estimates using analytical solutions based on classic elasticity and heat transfer theory. These closed-form solutions provide rapid estimates of structural and thermal behavior and an understanding of the governing parameters controlling the response. Finite element analysis (FEA) methods are widely used to provide more-accurate and higher-fidelity mechanical response predictions. Models of varying complexity may be developed by discretizing the structure into one-, two-, or three-dimensional elements to meet both efficiency and accuracy requirements. Thermal analysis models use both finite element methods and finite difference techniques to predict the thermal behavior of optical systems. Models are developed to predict thermal response quantities such as temperature distributions and heat fluxes that account for conduction, convection, and radiation modes of heat transfer.
Integrated optomechanical analysis involves the coupling of the structural, thermal, and optical simulation tools in a multi-disciplinary process commonly referred to as structural-thermal-optical performance or STOP analyses. The benefit of performing integrated analyses is the ability to provide insight into the interdisciplinary design relationships of thermal and structural designs and their impact through a deterministic assessment of optical performance. Engineering decisions during both the conceptual and execution stages of a program can then be based on high-fidelity performance simulations that are combined with program performance and reliability requirements, risk tolerance, schedule, and cost objectives to optimize the overall system design.