Design of a retinal tracking system for jumping spiders

We designed an optical system for tracking the retinal movement of a jumping spider as a stimulus is presented to it. The system, using all off-the-shelf optical components except for one custom aspheric plate, consists of three sub-systems that share a common path: a visible stimuli presentation sub-system, a NIR illumination sub-system, and a NIR retinal imaging sub-system. A 25 mm clearance between the last element and the spider ensures a stable positioning of the spider. The stimuli presentation system relays an image from a display to the spider eye, matching the 15 arcmin resolution of the two principal eyes and producing a virtual image at a distance of 255 mm from the spider, with a visual full field of view of 52°. When viewing a stimulus, the spider moves its retinas, which cover a full field of view of only 0.6°, and directs them to view different places in the visual field. The retinal imaging system uses a NIR camera to track changes of 0.5° in the field of view seen by the spider. By tracking retinal movement across images presented to spiders, we will learn how they search for visual cues to identify prey, rivals, and potential mates.