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.