Spatial Thermal Gradient Effects on Precision MEMS Resonator Zero Rate Drift
Spatial thermal gradients shift MEMS zero rate drift by inducing asymmetric anchor stress, flexure mode coupling, and local frequency splitting.
Asymmetric Flexure Expansion
Structural Deviation
Mechanical deformation occurs when thermal gradients across a supporting structure force unequal displacement along its primary axes. This asymmetric flexure expansion shifts the geometric center of precision stages and introduces tilt into optical paths. Such movement differs from uniform growth because the internal pivot points migrate relative to the mounting datum.
Because the chemistry of the metal is constant, the expansion is predictable but remains undesirable in sub-micron positioning tasks.
Geometric Bias
Mechanical bias stems from the design of the hinges. While a symmetric design compensates for temperature, asymmetric flexure expansion causes a parasitic rotation. Designers account for this by placing sensors at the neutral axis to minimize the readout of the induced arc.
Boundary Condition
Physical constraints at the attachment points restrict or enable the motion. If one side of a mount is fixed and the other is free, asymmetric flexure expansion results in a bow that distorts the flatness of the assembly. Manufacturers specify the flatness of the mating surface to prevent pre-loading the flexure into a non-linear region.
Measurement Uncertainty
Quantifying the drift requires laser interferometry. The asymmetric flexure expansion is measured against a reference bridge made of invar or zero-expansion glass. Calibration is stored in software.