BSU25 Series – Polarization-Insensitive 50:50

Introductionpolarization insensitive beam splitters
Ordinary beamsplitter components with AR/50%R coatings can be used with a circularly-polarized
input beam to give a 50:50 power split at 45° incidence, but they can dramatically affect the
polarization characteristics of the transmitted and reflected beams.
A typical ‘ordinary’ beamsplitter might give:
Rs = 65%, Ts = 35%, and Rp = 35%, Tp = 65%.
The result is elliptical-polarization of each of the two resulting beams.
A rugged, low cost solution to beamsplitting and maintaining polarization is provided by BSU25
beamsplitters. Two models of this polarization-insensitive class of beamsplitter are available, with
parallel and orthogonal output beam configurations.
Technical specifications
Dimensions : See Fig 70.211
Weight : 5 kg
Construction : Aluminium, black-anodised.
Connectors : Via free-rotating coupling rings, 52.0 dia x 1.5 pitch.
Water cooling : Via 8/6 connectors. Internally distributed.
Power split : Standard is 50:50. Options on request.
Power split accuracy ± 2%
Optics : Beamsplitter is ZnSe, P/no 15.7ZPF4-50N
Mirror(s) are Cu, P/no 19.7SMA10-00
Max power : 3kW cw (estimated).
Clear aperture : 30.0mm diameter.
Model designations
BSU25-S .. transmitted beam straight through, split beam – parallel, separated by 96mm.
BSU25-R .. transmitted beam straight through, split beam – orthogonal (at 90° to) input beam.
Associated equipment
BSU25 units connect directly to OPG piping (data section 61).
BSU25-S can be connected, via short lengths of OPG pipe, to two focusing heads (eg: FF25) to
provide the basis of a simple 2-head cutting system.
Applications notes
For ceramics scribing/profiling the use of advanced aberration-corrected optics (data section 20)
has led to better product quality and faster processing speeds at reduced laser powers. ‘Surplus’
laser power can be utilised by beamsplitting in order to double production capacity.
polarization diagram