And even if it is partly due to contamination, this doesn’t help that much — cleaning optics on this thing will be a real treat! The Doppler-broadened neon gain curve reslly respresents a distribution of atomic velocities, with zero velocity being at the center. None of these is really the way it appears in person, but they do look cool. 🙂 Spectra-Physics Model 259B Exciter — Overall View. It weighs about 25 pounds but a rack mounting kit was available.
This is before Hertz was used for cycles per second (cps)!. With the optional Servo Option 259-002 for active cavity length control using the Lamb dip for stabilization (which is actually more sophisticated than modern mode-stabilized HeNe lasers) it goes down to +/-5 Mcps/day. Interestingly, the laser tube anode is near ground potential, off of it by only the voltage drop across the current sense resistor. And, how much would anyone pay for that?
The white block contains the ballast resistor normally used with the SP power supply. The SP-116 was a tunable version of the RF excited SP-115. These used a Littrow prism in place of the HR mirror. The cylindrical laser head contains the tube, output optics, and beam sampling assembly. A view of the parts after disassembly is shown in Spectra-Physics Model 117 Stabilized HeNe Laser Head Components.