The effects of design parameters on the laser-induced in-plane deformation of two-bridge actuators

• Plastic deformation of the two-bridge actuator due to a laser pulse is modeled.
• The thermo-mechanical constraint ratio is expressed by design parameters.
• Increasing the ratio will increase the range of the laser micro adjustment.
• Decreasing the ratio will increase the resolution of the laser micro adjustment.
• Analytic formulae for the elastic-plastic behavior threshold are derived.

Laser-based non-contact micro-adjustment method is a way of going beyond limits of traditional mechanical techniques applied for precise alignment during assembly of miniature opto-electro-mechanical devices. The two-bridge actuator is an on-board structure that allows for adjustments with micrometer, sub-micrometer or sub-miliradian accuracy. Successful industrial application of the method requires a thorough understanding of mechanics of the laser-induced deformation process. The effects of two fundamental design parameters, i.e., the width and the distance between the bridges, on in-plane plastic deformation of the actuator are examined in this work. Experimentally validated theoretical model explains how design parameters, material data and laser pulse parameters affect the final deformation angle of the actuator. The derived mathematical formulae show dependence of the constraint ratio, thermal stresses and thermally-induced plastic deformation on the design parameters of the structure. The proposed solution can be used for optimization of two-bridge actuators.