Beam Splitters:

This makes both beamsplitters with a raster (polka dot) and with a neutral density mirror

Polka dot:
- Dot size is customer selectable to make the tradoff between moiré and diffraction
   at the dot edges
- Transmission can be anywhere in the 0.1%-92.5% range
- Very accurate and repeatable.
- Very good uniformity across a larger area.
- Light which is not transmitted is reflected, the reflection is typically 90% of the
   covered area. The beamsplitter absorbs a minimum amount of light/heat.
- The spectral curve is flat from 350nm to >2000nm, solely depending on the
   glass absorption.

Neutral density:
- Thin chrome or aluminium beamsplitters, no interference or diffraction.
- Light is partially absorbed. For Aluminium, typically 30% is absorbed
   in a 50/50 beamsplitter.
- Accuracy down to approx 2%
- Spectral curve is flat in the visible range for Al, also in the near IR range
   when Chrome is used.