WASHINGTON — If you think you see a green laser beam shooting across Chesapeake Bay this week, don’t worry, it’s not a martian invasion.

It’s just the U.S. Naval Research Laboratory.

The U.S. Naval Research Laboratory’s Chesapeake Bay Detachment is testing an eye-safe green laser beam at a range of 4 to 22 km (2.5 to 13.5 miles) across the bay to see how the laser system works at long range over water.

The testing will be during the day and night from June 26-30, but the lasers will only be visible when it gets dark.

During the day, the Naval Research Laboratory will test the beam from its detachment just south of Chesapeake Beach, Maryland, toward its site on Tilghman Island. It will be testing the beam at night due east toward one of their boats.

Testing will stop if any ship or aircraft comes within 300 meters (328 yards) of the beam.