Now see the current live article: after the introduction it quickly peters out into lists. The thing is start-class, and it's good basic science an encyclopedia ought to cover. If you wear glasses or do photography you use optics. Okay, ready for the fun? I promise this won't be too hard.
Have a look at ScienceApologist's draft improvements! Much bigger, much more informative, and well on its way. What he needs are nontechnical eyes to read it: has he been clear enough? Do the descriptions make sense? Please review, copyedit, and improve!