Begin by carefully cleaning the copper plate and the sapphire window with 70%ethanol. Use fine grit sandpaper to make rough copper plate surfaces smooth. Apply around 0.5 millimeter thin and even layer of thermal paste on three inner surfaces of the copper plate where the sapphire window will connect, and spread evenly.
Then lay the copper plate down while protecting the benchtop with paper. Insert the sapphire window into the copper plate hole ensuring the sapphire does not rotate during insertion. Remove excess thermal paste.
Adhere the four inch wide tape to the top surface of the copper plate sapphire window assembly, having a square depression area. Guide the adhesion slowly from one side to the other to avoid air bubbles during pasting. Cut out the area of the tape indicated with blue dashers from the assembly using a sharp blade, exposing the two thread holes, the square depression, and the 70 millimeter diameter area of the sapphire window.
Cut out the area adhered to the copper plate sapphire window assembly. Once done, tape the bottom surface of the copper plate sapphire window assembly and repeat the cutting procedure, exposing the two thread holes and the 70 millimeter diameter sapphire window.
