Nat. Methods 14, 11 (2017); published online 29 December 2016; corrected after print 21 June 2017

In the version of this Methods in Brief initially published, the citation Deán-Ben, X.L. et al. Light Sci. Appl. 5, e16201 (2016) was incorrect. The correct citation is Deán-Ben, X.L. et al. Light Sci. Appl. 6, e16247 (2017). The error has been corrected in the HTML and PDF versions of the article.