Mar 13

New Apple Patent for Light Field Camera …in Manufacturing Processes

New Apple Patent for Light Field Camera ...in Manufacturing Processes (Picture: Apple) Light field imaging has captured the mind of many technology enthusiasts and imaging pioneers, and there have been rumours of light field cameras in future iPhones or Android smartphones.
Now a new patent has surfaced that shows Apple is still interested in light field cameras. The twist is, the proposed “plenoptic” (a.k.a. light field) camera system is intended to aid robots in the manufacturing process. Continue reading

Aug 17

Ricoh Patents Dynamically Adjustable Multimode Lightfield Imaging System

Ricoh Patents Dynamically Adjustable Multimode Lightfield Imaging System (Fig. modified from Shroff & Berkner 2014) Ricoh researchers Sapna A. Shroff and Kathrin Berkner have lodged a patent application that describes a new way to dynamically adjust the recording parameters of a light field camera. The US Patent and Trademark Office has recently published patent application US20140192255, entitled “Dynamic Adjustment of Multimode Lightfield Imaging System Using Exposure Condition and Filter Position”, in which the authors use a non-homogeneous filter module at the pupil plane of a multimode imaging system, which can be moved and thus used to modify the imaging system’s exposure conditions. Continue reading

Aug 05

Samsung Patents Modified Light Field Sensor with Monochrome Sub-Images

Fig. 6 from Samsung's patent application shows three exemplary colour-filtered light rays passing through microlenses to create monochrome sub-images (Fig. modified from Lee et al., 2014). In order to record colour images, camera sensors typically use a colour filter array consisting of red, green, and blue filters on top of the light-intensity sensing sub-pixels. After recording each sub-pixel’s light intensity, the so-called “demosaic” process combines four monochrome sub-pixels (2x red, 2x green, 1x blue) into a single pixel containing RGB colour information.
In microlens-based light field cameras, this “demosaic” job may result in a blur effect around the boundaries of objects in the final image.
Image Sensors World found a patent application by Samsung which can solve this blur-problem: In the patent application entitled “Photographing device and photographing method for taking picture by using a plurality of microlenses”, authors Tae-Hee Lee et al. propose moving the colour filter in front of the microlenses (instead of having them behind the microlenses), creating single-colour sub-images. Continue reading

Jul 15

Visera Patents Integrated Light Field Sensor Manufacturing Process

Fig. 3 from the patent application shows a schematic of a light field camera including the proposed single-piece light field sensor (picture modified from Wang et al., 2014) Light field technology is making its way into the mainstream, but the production and assembly of some of its components has not quite reached an efficient scale of mass production.
A typical light field sensor consists of an ordinary image sensor and a microlens array (MLA) or printed mask.
In the assembly of light field sensors, one of the most vital processes is the precise adjustment of the MLA‘s position on the sensor. This adjustment is required for every individual sensor and can thus take up a long time. Since the MLA is usually positioned using screws or springs, physical impact on the light field camera may displace the light field sensor’s layers.

With patent application US 20140183334 A1 “Image sensor for light field device and manufacturing method thereof“, recently discovered by Image Sensors World, Visera Technologies is aiming for an integrated manufacturing method for light field sensors: Authors Wei-Ko Wang and colleagues propose a system where two layers of microlenses (and an intermediate space layer) are formed directly on the image sensor using semiconductor processes. Continue reading

Jul 01

Sony Patents Light Field Sensor with Full-Resolution 3D Stereo Output

With today’s light field sensors, extracting 3D stereo images from light field recordings typically results in a lowered effective image resolution – but that limitation may soon be history: Sony has developed a novel sensor design with overlapping pixels in two layers, that will allow 3D output without the typical decrease in image resolution. In Sony’s recently granted US Patent, Nr. US20140071244, author Isao Hirota introduces a dual level microlens array setup in combination with a sensor that consists of two layers of light sensitive pixel grids – front-facing and back-facing grids that are rotated at, for example, 45 degrees.
The described configuration allows different neighbouring pixels to share the same information from a single microlens while being allocated to either the left or right stereo views, resulting in higher-resolution 3D stereo output from a single-lens, single-sensor device (i.e. a “monocular 3D stereo camera”).

Fig. 8 from the patent application shows an example setup which uses both a multilens array (34) as well as an additional on-chip lens array (OCL, 35) and color filter array (33) to create a stereo light field image. Fig. 18 from the patent application is a diagram illustrating a CMOS image sensor in which pixels are arranged in a matrix of 2x2 and, for the second layer of pixels, rotated by 45 degrees for multiple perspectives output in the Bayer arrangement.
Fig. 19 from the patent application illustrates how the setup in Fig. 18 allows for nine perspective images (incl. 6 actual parallax images and 3 interpolated ones), making the setup suitable for a monocular 3D stereo camera. Fig. 27 provides examples of electric potential distribution of the light receiving face (back face) in a typical square (A) and triangular (B) pixel, showing that the microlenses can be circular, ellipsoidal or polygonal shapes to improve the lenses' extinction ratios.

Patent abstract: Continue reading