Traditionally, the iris has physical blades that move in order to change the amount of light entering the lens, either opening wider or closing down.
A new chemical iris proposes to turn tradition on its head, negating the need for physical blades and dramatically reducing the overall size of a camera module. Miniaturising the current physical iris blade system is problematic, as there still needs to be an actuator to move the blades.
Developed by researchers in Germany, the new iris uses transparent chemical rings that become opaque when a voltage is applied. At just 55 micrometres thick, the design will allow for much smaller and thinner camera modules for use in smartphones.
As outlined in a paper from the Journal of Optics, the design features two glass substrates pressed together with an iridium tin oxide (ITO) layer on each. They also both have a thin layer of the electrochromic polymer (PEDOT) which is formed into rings that create the chemical iris.
To turn opaque, the iris only needs a very low voltage (1.5V) which means it is ideal for smartphones and other mobile devices. The paper states that a 1,200 mAh battery gives enough power to maintain the iris-state for 60,000 hours.
As the aperture will be a perfect circle rather than shaped by overlapping blades, the shallow depth of field effect may also be more pleasing, delivering smoother bokeh.
At the moment, most apertures on smartphone cameras are fixed. This system could deliver more flexibility, bringing full manual controls for mobile photography a step closer.
The technology is still in its infancy, but the researchers plan to develop it further.
"We will now further investigate the potential of optimised electrochromic materials, with a particular focus on improving the optical contrast and, in particular, the control of the depth of focus - this is the decisive hardware parameter which determines the success of next-generation models in the smartphone business."