"Report number 6842-570."

"When radiant energy falls on an object, a part of this energy will be absorbed (A), transmitted (T) or reflected (R). It may also induce the object to fluoresce. Reaction to the radiant energy depends on the objects' characteristics which include the physical and chemical structure, optical density and refractive index. Objects may be inert like minerals or rocks where the optical characteristics change throughout their growth cycle. Therefore, the interaction between radiant energy and agricultural crops is also dynamic and changes during its growth"--Introduction, page [1].