Thomas Thomson shone the pen from a flat in Dundee's Hilltown area at firefighter Christopher Hutton and watch manager William Stoops who were responding to a call in the city's Stirling Court.
Fiscal depute Keith Robertson told Dundee Sheriff Court that Mr Stoops felt a "hot pin-prick" sensation when the "blue-purple light" of the laser hit his left eye.
He also had a "dot shape shadow" in his vision for about an hour afterwards. Police were called and Thomson was arrested at about 10pm on May 8.
Thomson, 38, of Kennet Walk, Dundee, who admitted shining the light into the firefighters' eyes was jailed for 41 weeks. Sheriff Richard McFarlane said: "I can't see any alternative to custody."