The Design I decided that this vision system would interface to a 68HC11E2, and should be easy for me to work with. This placed a few restraints on my vision system. I wanted to be able to gather the data and process it. Therefore, the total number of pixels was going to be limited. I needed a sensor which could generate a range of values based on the light level.
Solar cells are an interesting idea, and have pretty decent response times.
However, the typical range of these was only 0 to 0.5v, which isn't very good. I could condition the signal using some op-amps, but that made the part count go up, and made the idea complex. I also considered photo transistors. They are faster than CdS cells, but they don't have very wide response. They are also more expensive than CdS cells.