How to redirect the lasers in Testchamber 19 in Chapter 4?

• You have already obtained the first cube, which was on the floor.

• Obtain the cube to your left, at the ceiling you can place a Portal and then walk into a wall.

• Obtain the second cube by using the aerial faith plate. Place a portal above it and on the floor, then in mid-air fire another portal to where I aimed the cursor.

• Then, use laser chaining to open the door.

• Then, use laser chaining to kill the turrets and then raise the platform. After that you can use the aerial faith plate trick with the floor again and shoot a portal where I aim the cursor…

There's a jumping pad aerial faith plate. Use it!

1. Make blue portal on ground, make orange portal above jump pad, go through.
2. Gain momentum when landing on the plate, go through again.
3. Once at maximum elevation, make an orange portal on the wall opposite your destination. Repeat as many times as needed.

You need to use the aerial faith plate to gain the momentum and launch yourself onto those platforms.

Solution:

Put a portal above the aerial faith plate and the second on onto the floor. Use that to launch yourself or the cubes into the air. While you're mid-air, shoot the portal that was above the aerial faith plate to a different surface in the room. This will conserve the momentum you gain from falling down and launch you across the room.

Interesting - I kind of wish I had done it this way. I had a slightly different idea, which was a complete PITA on timing:

Portals above the faith plate, and on the middle of the floor, but rather than open the new portal while at the highest point of the trajectory from the floor portal, for some reason I had it in my head I needed to set my portal while I was between the faith plate and the portal directly above it.

i.e. in that very small fraction of a second I was trying to line up and fire my portal.

It worked fine, but took way too long and made me waaayyyy to twitchy on my mouse button :-)