Professor Richard S. MullerMichael A. Helmbrecht

MEMS for Adaptive OpticsMEMS for Adaptive OpticsAdaptable-Mirror Section

Mirror Substrate

Solder-BumpElectrical Connections

Movable Mirror ElementsScale ~10s to 100s m

Scale ~ mm to cm

Current-DriverElectronics

Array of Elevating Mirrors

Professor Richard S. MullerMichael A. Helmbrecht

How Can We Elevate the Mirror Elements?

How Can We Elevate the Mirror Elements?

• Magnetic Actuation– Solenoidal structures

• Electrostatic Actuation– Vertical comb-drives

• Thermal Actuation– Thermal-bimorph structures– Our initial design approach

Professor Richard S. MullerMichael A. Helmbrecht

• Mirror

Berkeley Bimorph ProcessBerkeley Bimorph Process

• Single-mask process

• Low-stress nitride (SixNy) and aluminum bimorph

• Other processes under consideration– Hidden actuators – Electrostatic actuators– Bonded mirrors

Current path

Mirror

Die photo - actuated, released mirrors

Professor Richard S. MullerMichael A. Helmbrecht

ConclusionsConclusions

• Bimorph actuator is small and can be fabricated under the mirror– Fill factor > 98%

• Bimorph actuators can be tiled in an arrays to actuate large numbers of mirrors

• Bimorph actuator provides large tip deflection (h = 10 m)• Models show frequency requirements are met (f>1 kHz)• Bimorph actuators have been fabricated

– Testing is underway