Holographers measure their exposures in mJ/cm² (millijoules per square centimeter), which is easily obtained by multiplying mW/cm² by the number of seconds in an exposure.

So, a reading of 3.0 mW/cm² and an exposure of 1 minute would equal 180 mJ/cm². A typical DCG (dichromated gelatin) hologram requires about 100 mJ/cm², though carbon printing will likely require much more due to its different nature.

Unfortunately reciprocity failure is an issue with DCG as well, but I hope that total energy as expressed in joules per unit of area will still help in determining UV exposures.