partially transparent yet partially reflective mirror 58 a resulting in the intensity perceived by the detecting source 64 being the combination of the additional transmitted portion 16 c with the combined intensity of 16 b and 16 d this causes the intensity perceived by the detecting source 64 to be of a different level for each scenario involving a different section in which the photoelectric beams 16 are interrupted if the photoelectric beams 16 are interrupted between the generating source 62 and the first partially transparent yet partially reflective mirror 58 a no beam intensity is detected if the photoelectric beams 16 are interrupted between the first partially transparent yet partially reflective mirror 58 a and the second partially transparent yet partially reflective mirror 58 b only 16 b is detected if the plurality of photoelectric beams 16 are interrupted between the second partially transparent yet partially reflective mirror 58 b and terminal reflective mirror 60 c 16 b plus 16 d is detected and if the plurality of photoelectric beams 16 is uninterrupted then 16 b plus 16 d plus 16 c is detected this allows the virtual guard gate for a gated community 10 to use a common area for generating and detecting the plurality of photoelectric beams 16 while still being able to.