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In `F33f`_`[optics`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Optics]`_`f, `!diffraction efficiency`! is the performance of `F33f`_`[diffractive`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Diffractive]`_`f optical elements – especially `F33f`_`[diffraction gratings`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Diffraction_grating]`_`f – in terms of `F33f`_`[power`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Power_(physics)]`_`f throughput. It's a measure of how much `F33f`_`[optical power`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Optical_power]`_`f 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`*0, the efficiency η reads η η = P P 0 . {\\displaystyle \\eta ={\\frac {P}{P_{0}}}\\ .}

>>Contents

• `F0af`_`[Grating efficiency`#grating-efficiency]`_`f

• `F0af`_`[References`#references]`_`f

• `F0af`_`[External links`#external-links]`_`f

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>>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:`:cite-ref-1[`F5bf`_`[1`#cite-note-1]`_`f]`:cite-ref-2[`F5bf`_`[2`#cite-note-2]`_`f]

• 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

`:cite-note-1`!1.`! `F0af`_`[↑`#cite-ref-1]`_`f "Diffraction Efficiency & Relationship between Diffraction Efficiency and Polarization". Shimadzu Corporation. 2012. Retrieved 1 November 2012.

`:cite-note-2`!2.`! `F0af`_`[↑`#cite-ref-2]`_`f "Technical Note 10 – Guidelines for specifying diffraction gratings". Newport Corporation. Retrieved 1 November 2012.

>>External links

• `:citerefchristopher-palmer2020`aChristopher Palmer (2020). "Efficiency Characteristics of Diffraction Gratings". `*Diffraction Grating Handbook (8th edition)`*. MKS Newport. Retrieved 13 March 2020.

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