Thanks to TG for the link!
Sony Proposes 2-layer Stacked PDAF
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SonyAlphaRumors quotes Japanese-language Egami blog describing a new Sony patent application - a 2-layer image sensor having RGB pixels on top, and PDAF pixels on the bottom. I guess PDAF layer only gets IR and residuals of red image from the top RGB layer:
Thanks to TG for the link!
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Thanks to TG for the link!

