I have worked with lasers used for medical applications and yes they are not something you want to just play around with, extreme caution is definitely needed. I would never try something like this as a sheer reflection off tank will cause eye damage and burning of skin. The ones I worked with you put the laser device into a confined machine where what you are seeing is all on LCD screen, and do to it causing burns, there are special full arm sleeve sections you stick your arms in to work on unit. I know a guy in London who burnt himself really bad from repairing a medical laser machine.