ZnSe Beamcombiners

ZnSe Beam CombinersIntroduction
All standard ULO Optics beamcombiner components are based on the use of ZnSe as the substrate material. The most popular type is for combining a CO2 beam at 10.6μm and a visible red (HeNe or laser diode) beam.
Dimensions/physical characteristics
ZnSe beamcombiners can be constructed in diameters from 10.0mm up to 100.0mm, and in thicknesses from 1.0mm to 10.0mm. Standard sizes are listed below for combining a red and CO2 laser beam.
The beamcombiner is tilted at 45 deg and transmit the long wavelength beam (e.g. 10.6μm) while reflecting the short wavelength (e.g. 633nm). In this way the visible beam can be combined with the CO2 beam to provide a ‘pointing’ beam for system alignment or process alignment, e.g. medical laser systems. The red beam indicates to the surgeon the location of the (invisible) CO2 laser beam.
Unless otherwise specified by the customer and made to special order, the standard tolerances are:
Diameter: +0, -0.10mm.
Thickness: ±0.10mm.
Parallelism: ETV within 0.03mm.
Flatness: Typically λ/40 at 10.6μm over any 25mm test diameter.
Transmission: ~99.0% at 10.6μm
Reflection: ~99.0% at 633 to 670nm
Performance with wavelength
The graphs in fig 3.20 show a typical standard beamcombiner performance for the visible region of the spectrum and for 9.0 to 11.0μm in the infra-red.
Beamcombiners can be optimized for other wavelengths – price and technical data on request.

‘Reverse’ Beamcombiners
Coatings providing the opposite effect, i.e. maximum T (short λ) and maximum R (long λ), are not available. ‘Reverse’ beamcombiner assemblies consisting of a standard beamcombiner and three RedMax mirrors are available however.

Beam Combiner Diagram

Fig 3.01: Reverse beamcombiner arrangement

Beamcombiner data

Fig 3.02: Typical reflectance trace for a standard beamcombiner