Beamsplitters separate incident light into two components consisting of a reflected and a transmitted band. Beamsplitters is designed so to achieve a specified reflectance and transmittance over a spectral range of interest. Beamsplitters are used also to separate two polarizations. Typically the splitter is situated in a 45°-angle to the incident beam

Reflectance and transmittance of neutral beamsplitters are to be close to a constant in a specified spectral range. Values of reflectance and transmittance can be expressed in percentage, for example, 50% and 50%, 30% and 70% and so on.

beamsplitter

 

This beamsplitter operates in the spectral range from 400 to 800 nm.

Target specifications: T=R=50% (unpolarized light)

Materials: TiO2/SiO2, Glass substrate

YouTube    The details of the design process are shown in Beamsplitter at normal incidence

OptiLayer allows designing beamsplitters exhibiting any specified ratio T:R, for example, T=30% and R=70% (left pane) or T=70% and R=30% (right pane). Spectral range of interest can be, for example, from 450 to 650 nm and AOI equal to 45 degrees.

beamsplitter

beamsplitter
YouTube  See the details of our design process in our video exercise at YouTube

 

immersed beamsplitter

 

The immersed 41-layer beamsplitter operates at AOI of 45 degrees in the spectral range from 400 to 500 nm.

Target specifications: Ts=Tp=50%

Materials: ZnS/Al2O3/MgF2, Glass substrate, Incident medium is Glass

Design method: Gradual evolution

Software tool: OptiLayer

 

YouTube  Find illustration of the design process at YouTube

 

We can design an immersed polarizing beamsplitter operating in the spectral range from 400 to 700 nm for AOI of 65-75 degrees. Refractive index of the corresponding prism is 1.85.

These design specifications were taken from Li Li and J.A. Dobrowolski, “New developments in thin film polarizing beamsplitters”, in Optical Interference Coatings, Vol. 9, OSA Technical Digest Series, (Optical Society of America, Washington DC, 1998), pp. 158-160.

Target specifications:

  • Ts[%] > 99.9% for wavelengths 400-700 nm at AOI from 65 to 75 degrees
  • Tp[Optical Density] > 3.0 for wavelengths 400-700 nm at AOI from 65 to 75 degrees

YouTube  Our video example at YouTube presents the details of the design procedure.  

 beamsplitter
beamsplitter

 

Materials with refractive indices 2.35 and 1.45.

Design Technique: Gradual Evolution

Software: OptiLayer

 

YouTube  Our video example at YouTube presents the details of the design procedure.

beamsplitter

 

The beamsplitter operates in the spectral range from 620 to 680 nm.

Target specifications: Rs=Rp=50%

Ten design solutions exhibiting excellent spectral performances.

Number of layers from 28 to 34 layers.

OptiLayer BBM or Monochromatic simulators will help you to select the most practical designs.

 

YouTube  Design process is illustrated by our video at YouTube.

 

 

Materials: Nb2O5/SiO2, Glass substrate

Design Technique: Gradual Evolution/Needle Optimization

Software: OptiLayer

 beamsplitter