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Jun 28, 2023

Cambridge Mechatronics has created a shape memory alloy actuator for cameras that combines auto-focus and optical image stabilisation (AF+OIS) in the same structure.

Designed to move the lens above an image sensor, the actuator uses eight shape memory wires.

"By placing shape memory alloy wires in a three-dimensional configuration around the lens, the single actuator can perform both OIS and AF functions simultaneously," according to the company. It is the company's "first actuator which is capable of integrated closed-loop AF+OIS. The product is already in mass production, and has been adopted in both the Huawei Mate 50 Pro and Porsche Design Mate RS."

The wires contract when heated by current passing through them – CML has its own control algorithm firmware and a controller chip, the CM824, which provides feedback by deducing wire length from wire resistance.

There are in four crossed-pairs of wires (see diagram), one pair on each side of a square between a fixed part and a moving part – the latter carrying the lens. In the diagram, the right hand corner post is fixed (as is its diagonal opposite, while the left post (and its opposite) moves with the lens. This system can also steer the lens in pitch and yaw.

Three sizes of actuator are available, suitable for 1/1.56, 1/1.3 or 1/1.43inch image sensors.

The eight-wire actuator product page has a video showing how it works