These Proceedings contain the extended abstracts of the NEWRAD 2021 Conference arranged online by NIST, Boulder, USA, June 21 - 24, 2021. The presentations are listed in the conference program at https://www.nist.gov/news-events/events/2021/06/14th-international-conference-new-developments-and-applications-optical  and at the Proceedings website http://newrad2021.aalto.fi/index.html