Questions about Beamsplitters
To maintain the specified split ratio, you should place the coated side towards your source.
Typically λ/4 or better.
These beamsplitters should have damage thresholds comparable to a standard commercial mirror, e.g. several hundred watts/cm squared.
The design angle for these products is 45 degrees. The reflectance will be slightly less at 0 degrees and would have insignificant impact on split ratio. These are patterned area metalic beamsplitters so their angle and wavelength sensitivity is minimal. This is their primary advantage.