Mandel is a German physiotherapist, naturopath and acupuncturist, who started with research into Kirlian photography as a means of diagnosing the source of pain and sickness in the body. There is a detailed introduction of Peter Mandel and his work in one of the later modules.
He developed a light set of 7 color encoded glass pyramids and a penlight, used in Light-Puncture, to introduce color into the body. This is the most effective, most direct method of using color to heal the body.
See "Technology" section in the left hand panel.