Beamsplitters are fundamental components in optical engineering, serving to precisely divide a single input beam of light into two distinct output beams. This division allows for the simultaneous analysis or utilization of the light's properties along two separate paths. a laser beam) into two (or sometimes more) beams, which may or may not have the same optical power (radiant flux). For a lossless beam splitter, R + T = 1. R = reflectance, T = transmittance, A = absorptance (ideally zero) When comparing beam splitters, always check whether the specified R/T ratio is for.