The airline passengers who prefer not to submit to the physical pat-down during secondary screening at airports will be able to opt for a new scanning method.

The US Transportation Security Administration (TSA) began testing a new type of walk-through security machine, which uses a technology called active millimeter wave, at Phoenix Sky Harbor Airport (PHX).

According to TSA, the new technology, which is also less invasive than X-ray technology used in TSA’s first pilot program, can detect weapons, explosives and other threat items concealed under layers of clothing without physical contact.

The airline passenger should step into the scanner and should remains still for few seconds, in two different positions. Two antennas will rotate around the passenger body in order to generate a three-dimensional image that looks much like a fuzzy photo negative.

Once the scan is completed the passenger will step through the opposite side of the millimeter wave portal.

TSA explained that active millimeter wave technology passes harmless electromagnetic waves and the energy emitted during this process is 10,000 times less than a cell phone.

To further protect the privacy of the passenger, the image is viewed only by security officers from a remote location from they cannot ascertain the identity of the checked person. Still they can communicate with the officer at the checkpoint, who initiated the scan procedure. Also a security algorithm is used to mask the face of each passenger.

In the coming months the new scanners will be tested at New York's JFK and LAX in Los Angeles and TSA plans to purchase eight millimeter wave units at a cost of $1.7 million to be used in additional pilots.

If you wish to better understand how the new technology works TSA has posted two short  movies on its website.