As a related aside, what is the 100x MPE safe exposure reading for an 8mm diameter pupil?
ILDA always publish it as 100x MPE or 100 MW/cm².
However, as this means nothing in the real world to many people (without calculating and as this relates most relevantly to the simple method) I've always wondered why they don't publish the standard as dual bracketed figure of 100 MW/cm² (XXmw / 8mm diameter) given that the pupil diameter is always an assumed constant.
Would make it much easier and safer for end users to implement if the figure was also quoted as a figure they could simply go out and use with a power meter with an 8mm sensor area. Obviously if sensor size if slightly different to 8mm eg 7mm (I'm not sure what the standard aperture is, then the figure could eg be quoted in terms of 100 MW/cm² (XXmw / 7mm diameter laser power meter head). Point is to make it easy for the end user to implement with a standard sized power head.
It takes away the risk or complication of further erronous calculation introducing end user errors or the risk of the end user interpreting 100 MW/cm² as 100 MW/ sensor reading.