Grating efficiency

Diffraction efficiency is the performance of diffractive optical elements – especially diffraction gratings – in terms of power throughput. It's a measure of how much optical power is diffracted into a designated direction compared to the power incident onto the diffractive element.

If the diffracted power is designated with ${\displaystyle P}$ and the incident power with ${\displaystyle P_{0}}$ the efficiency ${\displaystyle \eta }$ reads

In the most common case – the diffraction efficiency of optical gratings (therefore also called grating efficiency) – there are two possibilities to specify efficiency:

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