I have used a similar set up in the past. I placed the reciever as the upper resistor in the base drive of a high gain transistor and selected the collector resistor for good signal swing then fed the signal into a schmit trigger to clean it up. This, when properly applied gives a fairly wide range of accepance. Do not be overly concerned with the focus of the led, Just think of it as a flashlight. Arrange the setup to have the product pass as close to the reciever as possible so that it blocks as much of the incident light as possible. Also I assume that the product is at least semi opaque to theselected light spectrum. As Eric says Have fun Terry