Wide-angle lens miniaturization through foveated imaging

Abstract

In the recent years, there have been many improvements in optics miniaturization, including wide-angle lenses. However, the design of a miniature wide-angle lens (FFOV 180°) is not a simple task. In order to correct aberrations that are issue from the large field of view, many lenses are necessary. Moreover, the amount of distortion is usually very high for those kinds of designs.It has been reported that distortion can be used as a design parameter in order to control the local magnification of the image across the field of view. This control of the distortion can be used to enhance the quality of the information present at the center of the image at the expense of the sides, leading to a foveated design. By carefully adjusting the resolution across the field of view, less care can be given to correcting defects issue from the edge of the field. This sort of compromise is a promising way to release some constraints and could, for example, allow a reduction of the number of lenses in the system. The present paper explores the effect of the control of distortion toward foveated imaging on a wide-angle lens. The goal is to assess its potential for allowing the simplification of the system. In order to achieve this objective, a miniature wide-angle lens is modified into different foveated designs, each of them with different resolution targets. The starting design is a state of the art commercial miniature wide-angle. The conditions in which the system can be reduced are then analyzed. Finally, the results and findings are discussed.

Superimposed multi-resolution imaging

“…This type of optical design is highly compromised for wide-FOV systems if high foveal ratios are required (corresponding in this case to the ratio of the magnifications at the center and the periphery of the image) leading to a dramatic increase in optical complexity [2][3][4]. A related approach is to employ a lower-complexity wide-FOV optical design and only correct for aberrations over a small region of the FOV that can be programed dynamically using spatial-light modulators [12,13]; however, these solutions still require detectors with a very high pixel count.…”

“…Previous strategies to achieve foveated sampling include: the use of non-uniform sensors (with variable photoreceptor density, mimicking the variable sampling rate of the retina) [1]; optical distortion for foveated lens design [2][3][4]; computational integration of independent imagers with dissimilar resolutions [5][6][7][8][9] and the use of a single sensor segmented into multiple channels with dissimilar magnifications [10]. The high cost of hardware and the added complexity of non-uniform sensors, or the optical complexity of foveal optics design, usually make these solutions unattractive.…”

High Zoom Ratio Foveated Snapshot Hyperspectral Imaging for Fruit Pest Monitoring

“…Tis technology can compensate for the problem of low spatial resolution caused by the limitation of the COMS pixels of the SRDA. Depending on their implementation, foveated imaging techniques can be divided into three major categories: local aberration-corrected foveated imaging [34][35][36][37], multichannel fused foveated imaging [38,39], and local magnifcation foveated imaging [40]. Local magnifcation foveal imaging technology realizes the local magnifcation of the region of interest through the foveated channel to improve the object space resolution of the system and can be widely coupled with diferent detectors.…”

Foveation Pipeline for 360° Video-Based Telemedicine

“…First, specialized imaging sensors have been designed and applied to capture the scene with different resolutions. Examples are non-uniform sampling sensors [7], foveated optical distortion of the lens [8], and multiple-channel segmented single sensors [9]. Second, two or more cameras can be used and post-processed to generate a unified foveated image [9,10].…”