Re:Latest session

[JohnFP]

Well, it seems Bob is right on the money. Although I suspected shooting at a current (power) higher then what I tuned my etalon and laser for with a Michaelson would be somewhat risky, I had no idea of the sever changes.

Last night I cleaned the prism, both mirrors,etalon and the Brewster windows on my Ion laser. I check power after each cleaning and noticed that the non really made any difference except the Brewster's. I got about 20% more power out of the laser when I cleaned those. Without the etalon I am getting peak power about what the laser is rated for. I then played with the 514 and 488 lines. It seems the 514 line is more tolerant of the etalon tuning for nice fringes. Some of you may be able to explain this due to the competing lines close to each of those or something else. Here is the kicker. If I tune the etalon at about 5 (out of 10) on the dial I can get real contrasty fringes. As I increase the power to about 7 they start to jitter and at 8 they disappear altogether. At 8 I cannot get contrasty fringes not matter what I do to the etalon even after trying to tune or let set for a while to let the temperature stabilize. At 8 I can get fringes by detuning the laser but then I am at the power I was at 5. My conclusion is my water does not have a high enough flow rate to keep the laser temperature stable. I have a feeling the flow switch may not be working, which I may have to take apart and clean or I may get some 4 cable and try the other 265 power supply I have. The wires have been cut inside the second power supply and I do not want to dismantle the power supply I am using. This is typical of government surplus (wire cutting). I will do this just to see if it is something else that cannot handle the load in my existing power supply. But I really believe it is my flow rate. Anyhow no matter what. At 4 on the power dial I am getting 200mw @ 488 and very stable fringes. I will be shooting with that from now on until I find an answer. 514 falls off too much at that low of current and is about 200mw at 4 on the dial also. Since DCG is more sensitive at 488 I will continue shooting there. Cannot wait till this weekend.

I have an oven controlled etalon but cannot find a controller for it. Anyone have a controller for an intra cavity oven controlled etalon? I would also love a user manual for the Spectra Physics 165 Laser and/or 164 Laser and/or 265 Exciter.