colour filter

Fujifilm and Panasonic come together to create a thinner, more sensitive imaging chip

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.

Fig.1: A thinner light sensitive layer makes for a more efficient imaging chip

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.

Fig. 2: Higher dynamic range and lower noise levels

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.

Fig. 3: A larger light-gathering area means increased sensitivity

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.

Samsung adds to the mobile phone megapixel monster

Samsung sensors

Whether or not the megapixel race has cooled down, or at least reached a simmer, in point-and-shoot cameras remains to be seen, but it seems to be hotting up in mobile phones. Last autumn Sony unveiled a 16mp sensor; now it’s Samsung’s turn, with 8mp and 12mp imagers for use in a smartphone. Because we all obviously need that much resolution in a device with the photographic control of an earth-bound asteroid.

The catchily named S5K3H2 is the 8mp sensor. It has back side illuminated technology, which will go some way to helping get a picture that is actually of something, especially in low-light conditions, as well as the ability to capture 1080p full HD video images at up to 30fps.

The S5K3L1 (now I feel as if the Samsung engineers are misplaced megalomanic chemists with naming conventions like these) is the 12mp sensor, which improves on the 8mp sensor with an optional RGB-white colour filter and a video capability of 1080p HD video at 60fps and 720p at 90fps.

They’ll be rocking and rolling later this year. I think I can probably contain myself until then.