Development of Wide-Angle Fovea Lens Taking Into Account Rapid Camera Work

Wide-Angle Fovea sensor (WAF sensor) is a well-known visual sensor in the field of robot vision with unique specifications biologically-inspired from the primate visual system. Resolution of its input image is the highest at the center of its field of view (FOV), and rapidly decreases toward the peripheral FOV. The type of WAF sensor realized using a special-made wide-angle lens simultaneously achieves the following two contradictory characteristics: (1) wide FOV and (2) high resolution (although this is partially achieved only in the central FOV). In addition, the WAF sensor requires eye movement similar to the human eye, and is used in combination with a camera work device. The high-definition WAF lens we prototyped previously had a sufficiently high optical performance, but it had a weak point that its first lens surface on the object side could not be protected by the lens barrel or protective cover glass during camera work because of too much protrusion of the first lens. In this paper, we propose a high-definition wide-angle fovea lens that is designed to avoid damage to the first lens during high-speed camera work. In order to solve the above problems, we design and manufacture a prototype with the following two points as design goals. (1) It has the same target specification as the previous WAF lens. (2) In order to greatly reduce the protrusion of the first lens, in addition to the four surfaces in the front lens group used in the previous prototype, another aspheric surface is added to the rear lens group. In the prototype, we succeeded in significantly reducing the protrusion of the first lens from 10.4mm to 2.2mm. To evaluate its performance, we conducted imaging experiments and optical resolution inspection using MTF measurements, and discussed the results.