One of my favorite reference books is The Laser Guidebook, second edition.
It covers the basics of everything; HeNe, HeCd, ions, metal vapor, semiconductor, solid state, Hg and Au, free electron, eximer, x-ray, salt, you name it!
I LOVE this book. It is my all time favorite for when I need to do some background research on something, or a refresher on a concept.
If I'm new getting into something, like currently HeCd, or firstly, HeNe, it's wonderful. It'll give you the basics on everything, and explain the jargon, the parts, how it works, why it works, history, graphs of known wavelengths, all of it.
Plus it was pretty cheap from Amazon.
If you're looking for a whole hearted book that will give you the basics, and stepping blocks on ANYTHING you'd want to know, this is your book.
The only (small) downside is that it isn't updated with the recent things like blue diodes, or brand new DPSS. However, you could speculate how they work based on the concepts it does have. Then when you look them up, you will have the knowledge to understand how they are different from the examples in the book.
A great starter book