Monday, October 19, 2009

Some News on the Latest CMOS Imager Technologies and Developments

Last year, Sony announced their development of their new Back Side Illuminated (BSI) CMOS imager which they intended to use in their digital camcorders and P&S DCs (the sensor is small in size):-

Whilst the light receiving area per pixel are expanded and it well observes the law of Physics for getting more photons (and thus light power and finally energy) on the photo site, the technology is not yet quite mature and other technical issues arisen are yet to be resolved, e.g., more colour crosstalk as a result of less colour separation (thinner grids and partitions) for adjacent different Bayer filters and pixels.

Now that after one year, Samsung also talks about their new BSI sensor is coming. Samsung even dare telling us they are going to make slightly larger sensors (same pixel pitch, more pixel count, will explain more below) based on the same idea and technology:-
(in Japanese, or Google Translation in English here)

But from what are presented in the above (for the diagrams and word descriptions etc.), I am afraid that Samsung's BSI is just 99.9% identical to that of Sony, whom should be the original inventor (patented?) for that innovation and new technology. The pitch/pixel sizes disclosed are exactly the same, i.e., 1.75 um as mentioned, although the pixel counts are different (5MP of Sony Vs 14.6MP of Samsung). What a "coincidence"! And also, I just wonder why Samsung like the 14.6MP pixel count and number so much??

Btw, both sensors are much smaller in size anyway. Let's say a 12.4MP APS-C imager (say, the one used in the new K-x) means 4288 x 2428 in 24 x 16mm (approximately, 3:2), which just implies that the linear pixel size is 0.024m / 4288 = 5.6um. So each pixel is of area in the square of 5.6um. So, as for a 1.75um square pixel, which is just a much smaller sensor in size, even though if it has a much higher pixel count than the Sony prototype (14.6MP Vs 5MP), which is just by no means can match the size of any DSLR sensor format and system so far - Well, 14.6MP = 4672 x 3104. And, 4672 x 1.75um = 8.176mm, i.e., the sensor is only slightly more than 8mm for the long side. Do note that even 4/3 sensors are at roughly about 18mm in length for the long side (to put it simpler, let's assume the 4/3 is half-frame 135 in 3:2, although actually they are in 4:3, i.e., 18 x 12mm).

Next, at the other side, let us see the latest breakthrough in sensor technology and development of Fujifilm:-
(in Simplified Chinese, or Google Translation in English here)

So Fuji has been successful in making their own "Foveon", with some kinds of new "organic" technologies and theoretical improved sensor performance. Their prototype built is still experimental, though. And light fading problem (uneven spectral response/light sensitivity between RGB) of the original "Foveon" is yet to be resolved. I do hope they can succeed shortly and make new generation of superb sensors with their new technologies, as a result of their extensive and intensive R&D and investment made. When the day comes, I am sure all digital cameras will have improved performance, regardless of sensor sizes and formats, which will surely a good news to all people. And, there will be no more Bayer artifacts, which just means better image quality without any doubt. Moreover, demosaic algorithms will no longer be essentially required and much on-board processing power can be saved (and at the same time getting rid of the Bayer artifacts and moires).

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