I changed the Light but I eft the window as before. I like your solution without catwalk :)) So at least there ar two solutions. Thx for your advices.

Ian's Laboratories - 70s great look to the chamber. I did a couple things differently than your walkthrough. I used portals to fling myself into laser cube room. I didn't use the catwalk, I used the speed gel with portals on the wall and angled block. The rooms with the sphere gave me trouble. Getting the sphere was okay but the small area of portalable surface in the ceiling leading to the sphere button was very difficult for me to see. I ended up in the main area with the sphere and looking for a sphere button. I had to use the walkthrough before I realized where the sphere had to go. A little more light would have been helpful.
By the way, the window in the glass barrier wasn't necessary. Portalable surfaces on each side of the barrier gives opportunity for the "portal bump" glitch.