UV Iron

uv_iron_options={
  "uv_amp_const"  :{"bool":False, "uv_iron_val":1.0}, # hold amplitude constant?
  "uv_disp_const" :{"bool":False, "uv_iron_val":3000.0},  # hold dispersion constant?
  "uv_voff_const" :{"bool":True,  "uv_iron_val":0.0}, # hold velocity constant?
}