Diffraction efficiency

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title: "Diffraction efficiency" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["diffraction"] description: "Fraction of optical power diffracted by an optical element" topic_path: "general/diffraction" source: "https://en.wikipedia.org/wiki/Diffraction_efficiency" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Fraction of optical power diffracted by an optical element ::

In optics, 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 of grating.

If the diffracted power is designated with P and the incident power with P, the efficiency η reads \eta = \frac{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

References

1. (2012). "Diffraction Efficiency & Relationship between Diffraction Efficiency and Polarization". Shimadzu Corporation.
2. "Technical Note 10 – Guidelines for specifying diffraction gratings". Newport Corporation.

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