Irvine-based chipmaker Microsemi Corp. has acquired a specialized technology that helps detect weapons and contraband in airports, military posts, government buildings and other law enforcement settings, the company announced Tuesday.

The company bought the millimeterwave technology and related assets of Florida-based Brijot Imaging Systems Inc., which debuted a hand-held scanner in May that could replace controversial pat-downs at airports and other security check points.

Terms of the transaction were undisclosed.

Investors sent Microsemi shares up more than 3% in afternoon New York trading on the news of the deal to a market value of about $1.7 billion.

The buy strengthens Microsemi’s position in the security market as it rolls out one of the first wands for touchless pat downs.

This is the second acquisition for Microsemi this month.

It recently acquired Sunnyvale-based “fabless” chipmaker ASIC Advantage Inc., building its position in the profitable aerospace and satellite industries, according to company officials.

ASIC designs and makes integrated circuits for the aerospace, automotive, communications, industrial and medical markets.

Products include controllers, sensors, analog-to-digital and digital-to-analog converters, and radiation-tested devices.

Microsemi’s chips serve a variety of military, aerospace, consumer and industrial uses. Its products are built into satellites, digital televisions, X-ray body scanners and other devices. Customers include Cisco Systems Inc., Boeing Co., Hewlett-Packard Co., Dell Inc. and Samsung Electronics Co.

Microsemi is Orange County’s third-biggest chipmaker by sales and reported about $520 million in revenue for the 12 months through October.

It’s aiming to grow to $1 billion in annual sales, according to analysts, with acquisitions helping boost revenue.