ARGH!! Bad night! Just a few minutes of inattention. I neglected to remove a rubber/plastic cover from a power meter, the meter was then placed in the beam path of a 7W UV laser, the melting plastic deposited on the nearby lens, toasting the coating, trashing the ~12K$ lens! I don't like making little mistakes, big ones haunt me for weeks. Such is the life of a technician in the semiconductor industry. If are working you WILL f*ck up sometimes. I hate it when it happens.