Can gravitational lensing focus light?

Question

If it could then perhaps light from one galaxy bent by another galaxy or galaxies (perhaps a rotating cluster) could be focused into a single point of incredible power. This might have quantum relativistic effects and cause a bend or break in spacetime and black holes and stuff.
And what if that focal point hit earth - we would be frazelled and turned to a crisp! And all with very little warning no doubt.

Answer 1

Theoretically, yes, but that would be a massive (literally!) feat of engineering. Shaping a galaxy so that it acts like a perfect lens would be like randomly melting a blob of glass and getting a perfect lens. The odds against that happening would be so much against the odds, and further, to get a other objects so perfectly aligned that the light of one object gets perfectly focused on the other would be even more improbable.
But it's a cool idea.

Answer 2

Gravitational lensing does not create a sharply focused image. It can create an enlarged but distorted image of a distant object. Like all optical systems, it cannot increase the surface brightness of an image---it makes background objects brighter by increasing the size of the object, while preserving the surface brightness. Generally, the amount of brightening is no more than a factor of 20. This is enough to turn an almost invisible, incredibly faint galaxy into a merely faint, barely detectable galaxy. You're not going to burn anything to a crisp with gravitational lensing.

Answer 3

Yes it's possible to bend light like that but it happens over such large distances, you don't get the intense focus like from a magnifying glass.

http://csep10.phys.utk.edu/astr162/lect/galaxies/gravlens.html

Answer 4

Or a fab intergalactic disco light system!