A lot of the houses in my area were built before 240V mains lines became standard and were never upgraded. If you do have a 240V line then just use that, it is a lot simpler.
If you don't have a 240 line, then you need to get creative.
You can either use a step up transformer, aim for +10% more than the VA you need, and keep in mind that's VA not kW as power factor may not be >96% in the laser supply. If you need ~2kVA then 2.5kW/2.5VA is usually fine (STU-2500 in that case). Keep in mind that a standard 20Amp breakered 120V line can only sustain 2400VA. Your PSU shouldn't exceed that it looks like, but who knows, maybe the power factor is terrible. If you only have 15A breakered lines then you run two 120V lines in parallel (lines from different breakers ON THE SAME BREAKER-BOX LEG!!) for 30A max at 120V when using a step up transformer.
OR without a step up transformer run two 120V lines in series (hot and hot from each 120V line go to the psu instead of hot and neutral) FROM OPPOSITE LEGS OF THE BREAKER-BOX for 240V @ 15 or 20A max depending on what the breakers are rated.
US household "120v" (240v) standard service is 240V from the line in the form of 120-0-120. The pole pig is center tapped and that is the neutral line. The breaker box is divided into two legs, one side of the center tapped winding each. So between one leg and neutral is 120v and between the two legs is 240V.
