Matt, Yes, There is a concern on the failure at least a single fault - but I believe the IEC 825 requires a double fault protection, but others may know more. You would have to know what the faults of the micro are fail, on fail off, is there a software routine that can cause the problem (and trust me you don't want to go there. If you knew how the micro failed and how it causes the laser to exceed your permissible limits then rather than trying to figure out all the ways the system could fail in a "laser hazardous mode", you may be able to produce in your circuitry methods for fault protection. This circuitry and the components that make it up would then become critical and controlled components which would require tracking and verification. Gary
-----Original Message----- From: Matt Kilkenny [mailto:mkilke...@opthos.com] Sent: Friday, June 15, 2001 11:21 AM To: emc-p...@majordomo.ieee.org Subject: Laser Safety I have a question on lasers for ITE concerning IEC-825 and FDA requirements. According to IEC, class 3b lasers have to have safety doors (interlocks). Can automatic power reduction be used if you are not pumping the laser to a 3b class level of power. In other words, can we not put interlocks on the system if the 3b laser power has been reduced to a 3a or class 1 level through microprocessor limitating it? Or is their single fault concerns if the microprocessor fails? Thanks for any help, Matt Kilkenny mkilke...@opthos.com ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall," ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"