Shares of Billerica’s Bruker Corp. fell after the scientific equipment maker’s results for the first quarter declined and missed analysts’ estimates. The company also lowered its outlook for 2013, citing weakness in the Japanese yen. Profits for the first quarter declined 64 percent over the same period last year as revenue was affected by changes in foreign exchange rates. Bruker’s business in Japan represents about 10 percent of its total revenue. Bruker’s first-quarter net income was $5.4 million, down from $15.1 million a year ago.