Industrial automation requires sensors in order to detect and measure the variables in the production process. An important sensor in many such processes is the non contact range finder. This thesis discusses the various commercially available range finders suited to a sawmill environment and then presents a novel low cost intensity based range finder. A prototype sensor has been made and tested on a variety of surf aces. It has been shown to be insensitive to the surf ace colour and texture of the object under investigation and has demonstrated a measuring range from 190mm to 350mm. The recorded accuracy in this range was found to have a 95% confidence interval of 2.0mm. The sensor provides a linear relationship with distance and is expected to have a manufacturing cost under $100.