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 06

Pinlight Display: Light Field Glasses for Augmented-Reality Applications

Nvidia Pinlight Display: Light Field Glasses for Augmented-Reality Applications (picture: Siggraph 2014 website) Earlier this year at Augmented World Expo, Nvidia researcher Douglas Lanman gave a talk about Near-Eye Light Field displays, i.e. electronic glasses which allow users to experience both 3D and depth. When asked about Augmented Reality (AR) applications during the discussion, Lanman noted that creating a set of transparent glasses that would also include microlenses (or something equivalent) but still allow “normal” see-through vision, was a real challenge. He very briefly teased “pinlight displays”, which were to be presented at the same conference, but no further information could be found online.

In the Emerging Technologies section of the Siggraph 2014 conference (10-14 August 2014), Adam Maimone and colleagues from the University of North Carolina at Chapel Hill and Nvidia will be presenting their new invention in a talk entitled “Pinlight Displays: Wide-Field-of-View Augmented-Reality Eyeglasses Using Defocused Point-Light Sources”. 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

Jun 06

Nvidia Near-Eye Light Field Display: Background, Design and History [Video]

Nvidia Near-Eye Light Field Display: Binocular OLED-based prototype (Youtube Screenshot) About a year ago, Nvidia presented a novel head-mounted display that is based on light field technology and offers both depth and refocus capability to the human eye. Their so-called Near-Eye Light Field Display was more a proof of concept, but it’s exciting new technology that solves a number of existing problems with stereoscopic virtual reality glasses.

Nvidia researcher Douglas Lanman recently gave a talk at Augmented World Expo (AWE2014), in which he explained the background and evolution of head-mounted displays and the history and design of Nvidia’s near-eye light field display prototypes: Continue reading

May 27

MIT: Compressive Light Field Projection System for new Glasses-Free 3D Displays

Illustration of concept. A light field projector, build using readily-available optics and electronics, emits a 4D light field onto a screen that expands the field of view so that observers on the other side of the screen can enjoy glasses-free 3D entertainment. No mechanically moving parts are used in either the projector or the screen. Additionally, the screen is completely passive, potentially allowing for the system to be scaled to significantly larger dimensions. (picture: MIT Media Lab, Camera Culture Group)Today’s glasses-free 3D displays ususally consist of dozens of devices, which makes them not only very complex, but also bulky, energy-consuming and costly. At SIGGRAPH 2014 conference, Gordon Wetzstein and Matthew Hirsch from the MIT’s Camera Culture Group presented a new approach to glasses-free 3D that is based on projectors and optical technology found in Keplerian telescopes. Their novel method for “Compressive Light Field Projection” consists of a single device without mechanically moving parts.
Because it’s relatively cheap to build with today’s optics and electronics, the presented prototype could pave the way for cinema-scale glasses-free 3D displays. Continue reading