Is viewing a 'time tunnel' effect reflected off fog safe at 150mW-200mW? I was thinking of a Halloween effect. I see laser light show modules are often in this range and are obviously for long-term viewing. What do I need to know to keep everyone safe? I have viewed many of the threads and videos on youtube but I still don't have a very good idea how this effect is created, the principles behind it , or how to best create it. Any advice?