Passport Systems, a developer of nuclear threat detection technology, has raised $20.86 million in venture capital, according to a new filing by the company with the Securities and Exchange Commission. 21 separate investors participated in the offering.

Passport Systems, Inc. was founded in December 2002 to develop and commercialize nuclear resonance fluorescence (NRF), a technology invented by MIT Professor and Passport founder William Bertozzi, as well as other technologies, to address the threats facing the world after the terrorist attacks on September 11, 2001.

Passport Systems' technologies are applied to automatically identify sea, air and land cargo contents in a fraction of the time required by other systems. The company has completed the design, construction and test of a full scale cargo scanner prototype deploying all of its advanced primary and secondary screening technologies with more than $45 million in government and private funding.