Venus: What would happen?

[Naemeth]

What would happen if you put a huge lens (100m, maybe larger) in front of Venus with the focal point somewhere on the surface and kept the lens so the Sun's light would be permanently going through the lens?

[Steve Ward]

A very quick suntan and sore shoulders . . .

[ronin]

Cut a big trench in the surface rock of Venus as the planet rotated, which would kick up more dust and assorted muck and obscure the light that was coming in. May get a plasma at the focus.