and the local oscillator l impinge two inputs 77 and 78 of the optical hybrid both signal beam s and local oscillator l beam are divided by the first set of 3 db couplers and mixed together with an additional phase shift of 90 degrees the resulting four output signals a b c d all have 90 degrees relative phase difference of the form a s l b s u2212 l c s jl and d s u2212 jl in the preferred embodiment the coherent detector is used as described in the u s patent application ser no 10 669 130 u201c optical coherent detector and optical communications system and method u201d by the same team inventors incorporated herein by reference the coherent detector performs homodyne or self homodyne detection of the received signal in one embodiment the light source generates a pulsed optical signal in the preferred embodiment the data is transmitted using orthogonal frequency division multiplexed ofdm communications as disclosed by the same team of inventors in u s patent application ser no 12 137 352 filed jun 11 2008 main advantages of the proposed technique using beam combiner to sum the transverse scattered beam are 1 reduced number of high speed photodetectors and electronics 2 all the opto electronics such as photodetectors amplifiers adc do not have to be co located with the receiver aperture array optics.