As the title implies, do I always need one of these, and which one do I need, and why oh why are they so expensive?
The quick answer is NO, you do not always need to use an Optical Rail or a Breadboard. For example, many good opticians do excellent work in their shop using very simple testing aids, such as lots of wooden blocks. I’ve seen opticians test large mirrors which were supported on wooden stands and blocks. It really depends on the type of testing you need to do.
When do you really need an Optical Rail? When you have a bunch of optics hardware which is made specifically to reside and slide on a rail, and these are what you need to use, you probably ought to have that rail. Sounds kind of dumb, I know. But I have been faced with that problem in a lab. We had a bunch of really nice rail-mounted testing hardware, but no rail to be seen anywhere within 3 miles. That is just frustrating. If you need to slide one or more optical elements or detectors, etc. so that they move (smoothly) relative to one another, and then can be locked down where you want them to stay, you probably ought to have that rail so you can do your work. If you want to keep some optics fairly aligned to one axis, it might work. If you cannot afford to purchase a full-on Breadboard, or you do not have a crane to pick it up and move it around your building, there are some inexpensive Optical Rails with various attachments and hardware mounts which can be obtained from optical supply houses. If you must do your testing on a wooden bench, etc., then the Rail might be a helpful aid.
When do you really need an Optical Breadboard Bench? If you need to mount lots of optics and components all spread out on a 2-dimensional surface, and you want to be able to attach them to it (breadboard style) with all the same fasteners (usually 1/4-20 machine screws in the USA) then you probably will love a Breadboard Bench. They have a matrix of accurately spaced 1/4-20 tapped holes all over the flat surface, which by the way, can be quite flat! What usually happens is a lab is set up with a comfortable budget, so they buy a couple of massive 4 ft x 8 ft benches with super good support legs. (These wind up being heavy enough to use as anchors for the Queen Mary I.) Then 90% of the time, the optical setups they do require a tiny fraction of the space available on them. Oh well; I should not fret about stuff like that. These benches can be obtained in many styles, including some which have clever internal mechanical structures which reduce vibrations a lot, at least over certain frequencies! In case you simply do not have the budget, or perhaps do not have enough space for a ship anchor in your lab, you can also buy small Breadboards which are made to order, and are thin and light weight, which can be better than other options. I once had one I could pick up and move myself. If you plan to do serious interferometry where you will be counting fringes or using software to analyze the fringes and patterns, you are going to wish you had a good, heavy, monster bench, and have it mounted on an air piston isolation suspension. Unless you are working inside a subterranean cave, you will probably experience nasty vibration problems with any flimsy support table for your interferometer setups.
Why are they so expensive? Cause they are complex to build. If you don’t believe that, try making one yourself. And because the manufacturers have a captive audience.
Optics Lab Tips and Tricks 