LED arrived and seems to work fine!
The LED I ordered a few weeks ago from
LED-Replacement ($18.95 + $1.75 S/H) showed up yesterday. It seems to work just fine!
On the plus side, it's solid state, the light is very white with a bit of blue, and the driver/regulator/etc circuitry is included in the base of the bulb. Painless to install.
The only negatives I can come up with is that it is much brighter than the original GE-50 bulb, and changing the supply voltage on a regulated LED system does not change the intensity of the light. This is a mixed blessing; my eyes aren't so good anymore and the brighter light makes it easier for me to distinguish the reticule lines, but it also tires me out faster! I may fool around with a small dark filter, or join the 21st century with a CCD Eyepiece that connects to a USB port like
this one.
If it works, pretty nice setup for $100! I'll have to machine an adapter to fit the CCD to the TAI-6 autocollimator, but that's not a problem.
Actually, my knowledge of optics is very small. I've got a couple questions if that's alright?
1. These eyepieces are intended for microscopes. Are the eyepieces for autocollimators different than ones for microscopes?
2. This particular one comes with a 0.5x reduction lens. I don't know if that's good, bad, or indifferent. Anybody know how this compares to an autocollimator's eyepiece?
3. The resolution on this one is 640x480. Like anything else, you can get more if you're willing to spend more! Does anybody have a feel for whether this resolution is enough to enable work that is at least as good as can be done with the naked eye & eyepiece?
Thank you again, everyone, for the help with the LED.
Dave