Paradigm Industries Inc., a Baltimore start-up company that makes high-intensity outdoor lighting equipment, announced it has purchased a small California company in a $4 million stock swap.

Paradigm merged with Photo Acoustic Technology, a publicly traded firm in West Lake Village, Calif., just north of Los Angeles. Photo Acoustic makes devices to test contaminants on surfaces such as those on rockets and space shuttles.

The merger, completed June 27th, will give Paradigm access to Photo Acoustic's U.S. government contacts, a promising market for Paradigm's products, according to its president and co-founder, Richard B. Pazornik.

"The U.S. government is probably the largest user of lighting, not just in this country but in the world," Mr. Pazornik said. "So what we'll be doing is piggybacking some of our marketing efforts together."

Paradigm makes energy-efficient "ballasts," or power supplies for high-intensity discharge lighting, such as that found in streetlights, stadiums and some retail displays.

The new parent company, named Paradigm International Inc., will retain its two separate subsidiaries and will keep its headquarters in Baltimore. The Paradigm division also has a manufacturing facility in Santa Fe Springs, Calif., east of Los Angeles, and a research and development facility in Pune, India.

Photo Acoustic has annual sales of $900,000. Paradigm had sales of about $2 million from its start-up last October until the end of June.