The photodiodes are integrally formed on {TAIL ~ a substrate} in {HEAD ~ close enough proximity} so that the first and second photodiodes experience substantially the same environment 
The photodiodes are integrally formed on { TAIL ~ a substrate } in { HEAD ~ close enough proximity } so that the first and second photodiodes experience substantially the same environment
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH