Patent ID: 7649617

Claim:
A light detection system for detecting return light energy reflected from a target object, the light detection system comprising: a first optical beam splitter that splits the return light energy into a first splitter large light energy portion and a first splitter small light energy portion; a second optical beam splitter that splits the first splitter small light energy portion into a second splitter large light energy portion and a second splitter small light energy portion; a first light energy detector that receives the first splitter large light energy portion via a long optical path and the second splitter small light energy portion via a short optical path such that the second splitter small light energy portion arrives at the first light energy detector before the first splitter large light energy portion, and in the event that the second splitter small light energy portion exceeds a first threshold light energy level of the first light energy detector, generates a stop signal; and a second light energy detector that receives the second splitter large light energy portion and, in the event that the second splitter large light energy portion exceeds a threshold energy level of the second detector generates a latch signal or integrates to sufficient level, whereby, when the first light energy detector has generated the stop signal, the latch or integrator voltage level signal indicates that the stop signal was generated by the first light energy detector in response to the second splitter small light energy portion.