Neha Patil (Editor)

Diffraction efficiency

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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 P and the incident power with P 0 the efficiency η reads

η = P P 0   .

Grating efficiency

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

  • The absolute efficiency is defined as above and relates the power diffracted into a particular order to the incident power.
  • The relative efficiency relates the power diffracted into a particular order to the power that would be reflected by a mirror of the same coating as the grating, therefore attributing to inevitable reflection losses at the grating but not caused by inefficient diffraction itself.

    • References

    Diffraction efficiency Wikipedia
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