How much attenuation does a 15mm beam splitter have

The attenuation of a 15mm beam splitter depends on its type and splitting ratio, typically ranging from 1–50% per output beam for standard 50/50 splitters.General PrinciplesA beam splitter divides incident light into transmitted and reflected beams, with the attenuation determined by the splitting ratio. For a standard 50/50 non-polarizing beam splitter, approximately 50% of the incident light is transmitted and 50% is reflected, meaning each output beam experiences roughly 3 dB of attenuation relative to the input beam .Factors Affecting AttenuationType of Beam SplitterPlate beam splitters: Thin glass plates with a partially reflective coating; typically used at 45° incidence. The coating determines the fraction of light reflected versus transmitted, and some additional loss occurs due to reflection from the second surface and absorption in the coating .Cube beam splitters: Two prisms cemented together with a coated interface; designed to minimize beam displacement and often have slightly lower insertion loss than plate splitters .Polarizing beam splitters: Split light based on polarization; one polarization is transmitted with minimal loss, while the orthogonal polarization is reflected. Attenuation depends on the extinction ratio and polarization of the incident light .Coating and WavelengthDielectric coatings can achieve high transmission (>90%) for the transmitted beam and high reflection (>90%) for the reflected beam at the design wavelength.Metallic coatings (e.g., aluminum) typically have higher absorption, leading to slightly greater attenuation.Beam Size and ApertureA 15mm clear aperture is standard for many lab-scale optics. Attenuation is generally independent of beam diameter as long as the beam fits within the clear aperture without clipping .Typical Values50/50 non-polarizing plate or cube: ~50% transmitted, ~50% reflected, with 1–5% additional loss due to absorption and surface reflections.30/70 or 70/30 splitters: Transmitted and reflected beams are attenuated according to the specified ratio. For example, a 30/70 splitter transmits 30% and reflects 70% of the incident power.Variable or tunable splitters: Can provide continuous attenuation from 1% to 95% for one output beam using a combination of a polarizing cube and a half-wave plate .SummaryThe attenuation of a 15mm beam splitter is primarily determined by its splitting ratio, type, and coating. For a standard 50/50 splitter, each output beam typically carries about half the incident power, with minor additional losses due to absorption and reflections. For precise applications, manufacturers provide detailed transmission and reflection specifications for each wavelength and polarization.