Light Sensor Type, Please Help!

[Alexander McGee]

Basically, yes, just two positions. We use sterilizers here at work to to product life testing on our hand-pieces (drills, ect). We just got a new one and my job as a co-op is to build a robot to to repetitive test. It basically inserts a tray, closes the door, starts a cycle, waits for it to end, opens the door, removes the tray, cool the items, and then restarts the process.

The fixture will be mounted a few inches (likely 3) from the door. The door drops down into the machine to allow for tray insertion. I need to put a mark on the door so we can verify that it is indeed closed or open. I would like to use the light sensor to detect these marks on the door, or even just a single mark.

Also, the system is 24v, but can be easily modified for something else.

I would like the sensor to be able to output a digital signal, rather than an analog one. However, if this is not possible, i would likely need an amplified signal so that i may use it in line with a relay control.

Any suggestions on the type of sensor and part numbers?