Many manufacturers distribute catalogs that include extensive tutorial sections. You could really teach a pretty extensive engineering course on optics using nothing more than the front pages of the CVI Melles Griot catalog. In this post I’ll point you to some of these resources.

CVI Melles Griot

CVI Melles Griot has their documentation online. Look for the “cool tips” label in the lists of documents. Here are some examples:
Fundamental Optics
Gaussian Beam Optics
Ultrafast Theory (for femtosecond pulse lasers, like Ti:Sapph)

Edmund Optics

Edmund has a bunch of application notes on all matters optical. They’re quite general and well written. However, they’re not in PDF form, unfortunately. Here’s some general information on optical coatings.

Physik Instrumente (PI)

This company makes piezoelectric devices for moving objectives, and other applications that require low amplitude, precise, rapid movement. They have a great tutorial on their website.

Molecular Probes – Invitrogen

For the basics on fluorescence, antibody staining, organic ion indicators, and related applications, Molecular Probes has a great handbook.
Basic fluorescence
Calcium indicators

Hamamatsu

This Japanese PMT and camera company offers the excellent PMT Handbook.

Richardson Grating Lab

The Diffraction Grating Handbook is very clear, practical, and to the point. Here’s are some alternate links if you have trouble with the first.

Molecular Devices

Now on its third edition, the Axon Guide was most recently revised in 2008. It’s a good source of information for the instrumentation end of electrophysiology.