Fig. 4: Dynamic motion detection of the ACEcam.
a Optical flow as the ACEcam is translated in front of a checkerboard pattern at a distance of 10 mm. Here green dots represent the ommatidia illuminated by bright squares of the checkerboard, and the direction and length of the vector denote the motion direction and velocity of a bright square. b Optical flow as the ACEcam is rotated, with the dark spot indicating the calculated rotation centre. c Experimental setup to generate very high angular velocities for the dynamic response measurement. Five LEDs are evenly spaced along 180o and lit up successively with a delay time ∆t whose minimum value is equal to the response time of the photodiode Δtdec, and five photodiodes are employed to record the light emitted by the corresponding LEDs. d, e Response signals of the photodiodes (upper panel) when the LEDs are driven by square waves (lower panel) of fflicker = 240 Hz in (d) and 31.3 kHz in (e). f Signal transmission pathway in the natural ommatidium. g Signal transmission pathway in the artificial ommatidium
