The device has 4 photodiodes and their amplification circuits. It has been designed to acquire analogue signals of different visual stimuli displayed on an LCD monitor. The information being encoded in 4 bits of information. It could be potentially used to record grayscale but it has not been explored. The main components are the four photodiodes (Osram BPW34S) , two dual transimpedance amplifiers (Texas instruments OPA2380) and a first order low pass filter (fc = 1kHz) for each amplification circuit.

We evaluated the performance of a single channel at different frequencies 10kHz, 100kHz, 500kHz and 1 MHz