Linear angle sensitive pixels for 4D light field capture

Abstract

In this paper we present the design of an image sensor pixel which produces a linear response proportional to the incident light angle. Unlike conventional pixels, the proposed pixel encodes incident angles in terms of linear intensity variations. A set of four pixels can distinguish between incident light angles along both the vertical and horizontal directions. This coarse linear angle information can be combined with the precise nonlinear Talbot effect based pixel response to deduce the exact incident angle. This technique greatly reduces the complexity of the Talbot effect based technique. Fabricated in a 65 nm GlobalFoundries mixed-signal CMOS process, the sensor can distinguish between angles in the range from -35 • to +35 • .

Polarization-Based Angle Sensitive Pixels for Light Field Image Sensors With High Spatio-Angular Resolution

“…In [16] and [19] we proposed an alternative approach to the Talbot-only technique of angle detection. We proposed to combine the response from the Talbot pixels with the response from a quadrature pixel cluster (QPC).…”

“…One such technique [16] -the track and tune image sensor, was based on using the metal shading based [17], [18] quadrature pixel cluster [19] in order to achieve a high spatial resolution (13 pixels for bi-directional angle detection) while enabling a wide angular resolution (±35 • ). The essence of the trackand-tune technique was to use a group of pixels with low sensitivity, but high linearity (quadrature pixel cluster) along with another group of pixels with high sensitivity, but low linearity (Talbot pixels) to determine the local incidence angle.…”

A Novel Hybrid CMOS Pixel-Cluster for Local Light Angle, Polarization and Intensity Detection with Determination of Stokes Parameters

“…Results presented in [13] show that the QPC angle sensitivity does not present significant change for a large range of metal shielding ratio of the pixel photosensitive area, 30% to 70%. Thus the shielded area of the pixels A and C of HPC cluster was designed to be 25% of the pixel photosensitive area.…”

“…12. This is a 3D view of the cluster with δ C variation of the light incidence in the photodiode [10,13,14,15], consisting of a block of metal on the top of the four photodiodes in such a way that the area which receives the incidence of light is proportional to the light incident angle. As detailed in [14], in this cluster, the direction of incident light is determined as follows:…”

“…The PPC embeds an unshielded pixel for local light intensity detection, a horizontal grated pixel strongly sensitive to 90º polarized light, a vertical grated pixel strongly sensitive to 0º polarized light, and a 45º sensitivity pixel used to determine the Stokes parameters [4,10,12]. The second set of pixels, to determine the incident angle sign is the quadrature pixel cluster (QPC) with a block of metal on the top of the four photodiodes [13][14], as shown in Fig. 2(b).…”