Photostimulator is a system for the delivery of defined light stimuli for vision research. The system consists of several autonomous components; light bulb, monochromator, continuously variable neutral density filter, polarizer and the components, designed for transfer and interpretation of captured data. The first part of the thesis deals with implementation of density filter control system. The component, designed for controlling the intensity of projected light, consists of 5 smaller, coherent parts. The neutral density filter, attached to a linear rail, which is driven by stepper, sets the intensity of projected light. The stepper is controlled by a stepper driver, which gets the data from the Arduino Due microcontroller board. All logic, for setting and controlling the density filter system, is contained within Arduino. The first part of the thesis describes the composition and functioning of system. In the second part, the thesis focuses on the density filter control system.