A beam splitter apparatus (1) of the present invention is provided with demultiplexing portions (13a and 13b) that split an input pulsed light beam (L0) into a plurality of optical paths (11a, 11b, 12a, and 12b) relay optical systems (141a to 144a and 141b to 144b) that individually relay the pulsed light beams in the plurality of optical paths a multiplexing portion (13c) that multiplexes the plurality of pulsed light beams (L1 to L4) that have been relayed through the optical paths and delaying portions (12a and 12b) and divergence-angle setting portions (151a and 151b and 152a and 152b) that respectively give the pulsed light beams, which are individually guided through the plurality of optical paths, relative time delays that are large enough to separate the signal lights (LS) and divergence angles that are different from each other.
