Current light field sensors typically consist of an imaging sensor and a separate microlens array, both of which are assembled into an optical system. While this allows the use of common CCD- or CMOS sensors, it may also introduce some issues where extreme precision is needed for optimal imaging conditions, e.g. with microlenses of micrometer-range focal lengths. A mismatch of these separately fabricated elements can affect image quality.
A new patent application by Jong Eun Kim at SK hynix (Korea) aims to solve these potential issues: The patent application details a novel light field imaging device where the microlens array is formed on top of the imaging sensor.
The sensor (red in the figures) is first covered with an optically transparent protective layer, then with a “sacrificial layer” (green) with embedded support structures (gaps in green; this is later removed), and finally the microlens array (blue) on top.
The invention also discusses the possibility of forming multiple sub-microlenses (yellow) underneath each microlens, coupled with colour filters to allow separate imaging of specific colour ranges within each microlens.
The author suggests that such a single-chip light field sensor would lower production and assembly costs, increase precision of the optical system and allow overall smaller devices, compared to light field sensors consisting of separately fabricated parts.
The complete patent application can be found at the US Patent and Trademark Office website: #0170179180: Light field imaging device and method for fabricating the same