Which of the following initiator accelerator system uses light activation composite?
The light-cure process is activated when a diketone photosensitizer such as camphorquinone (CQ) absorbs a quantum of blue light and forms an excited-state complex (exciplex) with an electron donor such as an amine (e.g., dimethylaminoethyl methacrylate ).
While in this activated complex, CQ extracts a hydrogen atom from the α-carbon adjacent to the amine group, and the complex decomposes into amine and CQ free radicals. The CQ free radical is readily inactivated.  
Thus, in photoinitiation only the amine free radicals act to initiate the addition polymerization reaction.
Reference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 289
Diketone-amine
Organic acid-metal oxide
Organic acid-peroxide
Peroxide-amine