pointless lightsaber question

Imagine that Boba Fett is attempting to kill Luke Skywalker. Luke is standing out in the open, and Fett is flying overhead in his spaceship, Slave I. Fett has outfitted his ship with a laser cannon as thick as a man’s thigh, and fires it at Luke. Luke, rather than dodging, brings up his lightsaber to block the bolt.

What happens?

The lightsaber’s blade is thinner than the blaster bolt. Does the lightsaber deflect the entire bolt, or does some of the bolt leak around the edges, frying Luke where he stands? Assume that Luke summons up the Force to strengthen his arms, so that the bolt doesn’t simply knock the lightsaber out of his hands.