Irvine-based Biolase Inc.’s shares surged today after the company said it received a commitment from an investment firm to buy $5 million of its stock.

The laser maker’s shares were up 12% to a market value of about $71 million at midday.

Biolase said in a release that Boston-based Camber Capital Management LLC would buy 2,688,172 shares of the company at $1.86 a share, which is equal to yesterday’s closing price.

The deal is expected to close on Friday, Biolase said.

Biolase’s shares have had sharp ups and downs in recent weeks on a variety of news, particularly centering on its loan deal with Dallas-based lender Comerica Bank. Biolase amended its credit deal with Comerica earlier this month.