Hi there,
The basic idea is, I'll be using, let say a torch light, directed at the white screen, light will be distributed all across. Then, I gotta build some sort of device, photometer? photodetector? to measure the intensity of light at, let say at 2cm interval, along the distributed light. Got what I mean? So first, I need to construct a circuit for measuring the intensity, and to display them. Secondly, I suppose I'll be needing a program. Third, I need to make it move in a straight line, along the light distribution, someone suggested that I get a stepper motor. I need major help as this project is due in 2-3 weeks time..