Light Sensor interface for data logger

Equipment: 1. Hobo Pendant Event Data Logger (UA-003-64) (Logger) 2. Hobo Pendant Optic USB Base Station & Coupler (BASE-U-1) (Coupler) 3. Island Research Passive Infrared Tracker Counter (Counter) ([login to view URL]) Need: To link the Counter to the Logger without penetrating the Counter’s casing. The Counter is a sealed unit. Idea: The counter has a red LED that flashes each time a count is recorded. A sensor to detect the light would provide an elegant solution. Progress: A circuit casing has been milled to fit into the Counter, but can be modified depending on circuit size. A trial with a photodiode was partially successful but not useful. The photodiode is sufficient to record an event if exposed to daylight, but was not sensitive enough to detect the Counter LED. Question: What is an estimate to have a circuit designed and a proof of concept circuit built?