Portal 2 Chapter 4 Test Chamber 20

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Portal 2 Chapter 4 Test Chamber 20
sp_a2_triple_laser.bsp Triple Laser

Chamber number 2.pngChamber number 0.png

Test Chamber Infobox previous.png
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Test Chamber Infobox Portal Guy.png
Chamber progress 2.pngChamber progress 0.pngChamber progress slash.pngChamber progress 2.pngChamber progress 2.png

Portal 2 Chapter 4 Test Chamber 20.png
Chamber icon fling enter.pngChamber icon fling exit.pngChamber icon light bridge.pngChamber icon player button.pngChamber icon laser sensor on.png
Chamber icon laser redirection on.pngChamber icon faith plate.pngChamber icon turret hazard.pngChamber icon laser hazard.pngChamber icon dirty water.png

This is the twenty-ninth level of the game, and is the first level to be set within a fully-repaired and functional Aperture Science Test Chamber. This level requires the player to combine precise Portal-placement and multiple Thermal Discouragement Beams in order to proceed.





  • Complete GLaDOS' Test Shaft (Test Chamber 20)



  • Aperture Science Enrichment Center
  • Test Chamber 20 (GLaDOS)


  • Walk over to the Beams and place a portal on the wall on the left-side where the Beam ends.
  • Place the other portal to the column facing the three Receptacles.
  • Pick up the cube that is already redirecting one of the Beams. Place the cube in front of the portal, so the Beam activates the middle Receptacle.
  • Pick up the other cube and place it over the beam coming from the ceiling. Aim it at the Receptacle on the right side.
  • Go to the Chamberlock.

It is also possible to complete this chamber without placing any portals if you position the cubes correctly and use a cube and quickly move the cube from side to side. If you do it correctly, holding down the strafe right movement key (default D) the door will open for a split second, letting you slip inside. This is a more difficult solution to the puzzle so the basic solution is recommended.

Video walkthrough

Download Download demo file


Main article: Portal 2 soundtrack

Triple Laser Phase by Aperture Science Psychoacoustics Laboratory [4:15] | Download Download | Play icon.png Play