{{short description|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 {{mvar|P}} and the incident power with {{math|''P''{{sub|0}}}}, the efficiency {{mvar|η}} reads <math display=block>\eta = \frac{P}{P_0} \ .</math>
== 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:<ref>{{cite web |url=http://www.shimadzu.com/products/opt/oh80jt0000001v0w.html |title=Diffraction Efficiency & Relationship between Diffraction Efficiency and Polarization |author= |year=2012 |publisher=Shimadzu Corporation |accessdate=1 November 2012}}</ref><ref>{{cite web |url=http://gratings.newport.com/library/technotes/technote10.asp |title=Technical Note 10 – Guidelines for specifying diffraction gratings |author= |date= |publisher=Newport Corporation |accessdate=1 November 2012}}</ref> *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 />
== External links ==
*{{cite web |url=https://www.gratinglab.com/Information/Handbook/Handbook.aspx |title=Efficiency Characteristics of Diffraction Gratings |author=Christopher Palmer |year=2020 |work=Diffraction Grating Handbook (8th edition) |publisher=MKS Newport |accessdate=13 March 2020}}
Category:Diffraction