Modern Lighting Instruments:
The Plano-Convex Lens Spotlight
http://micro.magnet.fsu.edu/primer/java/lens/p-convex1.html
http://en.wikipedia.org/wiki/Lens_%28optics%29#Types_of_lenses
http://www.daviddarling.info/encyclopedia/P/plano-convex_lens.html
http://www.optics-online.com/pxp.asp
The Fresnel lens spotlight
http://www.lanternroom.com/misc/freslens.htm
http://science.howstuffworks.com/question244.htm
http://www.britannica.com/eb/article-9035384/Augustin-Jean-Fresnel
http://www.bhphotovideo.com/c/product/163427-REG/Arri_530102_150W_Fresnel_220V_.html
http://www.stagelightingstore.com/s.nl/sc.25/category.153/.f
http://www.dreamstime.com/fresnellens-image1599813
The Ellipsoidal Reflector Spotlight
http://www.gweep.net/~prefect/pubs/iqp/node65.html
http://en.wikipedia.org/wiki/Ellipsoidal_reflector_spotlight
http://oswald.conspirators.net/lighting/ers.htm
Last update: November 15, 2007