Tonight I stumbled across http://www.controlledenvironments.org, a USDA website on controlled environment growth chambers. This is a quote from their home page:
North Central Extension & Research Activity–101 (NCERA-101) is a committee of the USDA organized to help plant scientists understand how to use controlled environment technology effectively and consistently. It evolved from a group of plant scientists in the American Society for Horticultural Science, who in 1969, began discussing how to utilize growth chambers effectively to ensure consistent and comparable growth data among laboratories.
The publications page [broken link, see below] is interesting. In particular, chapter 1 of the Plant Growth Chamber Handbook [broken link, see below] has good in-depth details on lighting requirements for photosynthesis.
[edit: @Webb.Peter, I just realized you linked to this before, but I never clicked through far enough to find the good stuff on photosynthesis]