Eyes aren't open at 15 weeks so it probably won't work yet. I don't understand why people want to hurt their little ones eyes by doing that to them.
I use the flashlight app when my baby keeps abusing my ribs.. Oh, it works!! Baby HATES that and moves lol.. I just shine it over my stomach.. I'm 30wks.. It might be a little early for your baby
My baby reacts to light music and when her big sister talks to her its amazing to see im 33 weeks