My wife has a home laser hair-removal machine that she likes to use before going to the mikvah. Since some of the places on her body are harder to reach she can’t do it alone. Being as how she is still t’meiah at that time, am I (her husband) allowed to help the procedure in the areas she cannot reach?
Excellent question. The famous Noda Beyehuda (Rabbi Yechezkel Landau 18Century) was asked a similar question if a couple who live in a desolate place where there is no female to supervise the tevilah, can the husband supervise his wife submerging under the water. He was lenient in his ruling based on the fact that she was already in the mikveh and only a very short time would elapse until his wife became tahor. In your case since she the procedure is done at home and there is the option to get female help if necessary, you should refrain from helping her.
Responsa Noda Beyehudah Y;D 2:122