The development of the imaging chip has focused overwhelmingly on resolution, and the desire to cram more and more pixels onto smaller and smaller sensors. However, improvements to image quality can only come from so much increased resolution; the focus now needs to shift to improving dynamic range, sensitivity, and pixel accuracy. We’ve already seen the potential for a graphene sensor developed at the Nanyang Technological University, but camera manufacturers are also looking to improve sensor technology, too. To this end, Fujifilm and Panasonic have been collaborating on a thinner, more efficient sensor.
Between them, with Panasonic focused on boosting image quality with semi-conductor device technology and Fujifilm devoting its attentions to an organic photoelectric conversion layer (more on those in a moment), they have developed an organic CMOS sensor with higher dynamic range, increased sensitivity, and a wider incident angle. This should lead to better image quality from smaller sensors.
A conventional image sensor comprises a silicon photodiode to capture light, a metal interconnecting layer, a colour filter, and an on-chip micro-lens. Fujifilm has swapped the silicon photodiode for an organic photoelectric conversion layer. This is more sensitive than the silicon photodiode as well as significantly thinner.
Panasonic’s contribution has been to increase the ability of sensors to handle electronic signals, preventing highlight clipping and reducing noise. It estimates that these new sensors have a dynamic range of 88dB.
Furthermore, between them Fujifilm and Panasonic have managed to increase the area of the sensor capable of harvesting light. They estimate this should boost sensitivity by 1.2 times compared to a conventional sensor, helping to capture images in lower light settings.
Finally, by swapping the silicon photodiode for the organic photoelectric conversion layer and reducing its thickness, there’s been an increase in the angles from which the sensor can detect light. Instead of an incidence of 30 to 40°, you’re now looking at about 60°. You can see this illustrated in Figure 1. This should allow for for more faithful colour reproduction and possibly more flexibility when it comes to lens design.
If you’re at the 2013 International Image Sensor Workshop to be held in Utah on 15 June, you’ll be able to hear more about the technology. However, they are anticipating it will be used across the spectrum of imaging products, so I suspect we’ll be hearing more in the future.