Kinematic Mount Selection for Optical Scanning Assemblies
Kinematic mount selection for optical scanning assemblies isolates substrates from thermal and dynamic distortions while maintaining sub-microradian repeatability.
Flexure Hinge Stiffness
Meaning
Resistance to angular or linear displacement in a frictionless compliant mechanism governs the force required to achieve a specific range of motion. Calculation of flexure hinge stiffness depends on the geometry of the notch and the elastic modulus of the material used. It determines the resonant frequency of the positioning stage and the power required from the actuator.
Mechanical Resistance
Thin sections of the hinge act as a spring when subjected to bending moments. Low flexure hinge stiffness facilitates large travel ranges but makes the system more susceptible to external vibrations. Conversely, a stiff hinge provides high bandwidth control at the expense of a higher heat load from the motor.
Calibration Procedure
Measurement of the displacement under a known force confirms that the manufacturing of the notch meets the design tolerance. Any variation in the thickness of the web significantly alters the flexure hinge stiffness because the value scales with the cube of that dimension. Precision machining is required to maintain consistency across a production lot.
Stability Boundary
Fatigue life decreases when the displacement causes the material to approach its yield strength. The hinge must operate within the elastic regime to avoid permanent set or eventual fracture. Determining this limit ensures the mechanism survives millions of cycles in a high speed scanning application.