Folded optics architecture is the next generation of zoom dual cameras in smartphones. The ever-demanding market need for maximizing the zoom experience results in long lenses, wide apertures and thick camera modules, making these cameras impossible to embed in a thin device.
Corephotonics’ folded optics architecture folds the light by using a prism and orients the lens barrel such that it is parallel to the phone surface. To allow for sharp images, our camera consists of a closed-loop fast auto focus (AF) mechanism. The AF mechanism shifts the lens closer and farther away from the image sensor.
It uses a voice coil motor (VCM) structure, designed especially for folded structure cameras. The VCM structure consists of a magnet and a coil, which shifts the lens, and a Hall bar (high precision position sensor), allowing for fast control to accurately set the lens in the exact position.
The AF mechanism supports a very large lens stroke, allowing the long focal length lens to focus at any distance ranging from infinity to 20cm, creating vivid macro shots with true optical Bokeh (shallow depth of field).
In addition, Corephotonics’ folded camera can be equipped with an optical image stabilization (OIS) mechanism, which makes it best suited for low light shots.
The embedded OIS system tracks the camera’s tilt using an embedded gyro and mitigates the effects of handshakes on the image.
Employing conventional OIS mechanisms, which shift the lens barrel on the two axes that are perpendicular to the optical axis, compromise the height of the camera and limit its performance.
Our OIS actuator overcomes the above limitations by splitting the OIS functionality between the prism and the lens assembly. We shift the lens in one direction to compensate for shakes along that axis and tilt the prism in the other direction to mitigate shakes along the second axis.
This allows for an increase in exposure time by a factor of 4 (two stops) while keeping the image sharp.