What to do for alignment?
Bad alignment:	Repeat the alignment procedure in step 2.1 as required. Because the IR beam diameter is large, most of the beam will pass the irises even if it is not perfectly aligned. Even if two bumps are still observed, the amount of the 1F signal can be increased by tuning one or both of the alignment mirrors. Watch for slight changes in the curvature of the first bump. Most of all, be patient since this is the most difficult part of the alignment.
Medium Alignment:	Try to adjust one or both of the alignment mirrors to obtain a nearly good alignment. Try moving the XYZ translational stage as well, BUT adjusting it by very small increments.
(Nearly) Good Alignment:	Adjust the mirrors and try to increase the maximum of the first bump. 1F signals are usually around 8 to 16 V, for low input powers it is less. Change the phase by changing the voltage using the piezo driver so that the first minimum comes closer to zero. If there is a significant 1F signal, switch the reference of the lock-in amplifier to isolate the 2F signal. Some of the signal should be observed and try to improve it a little bit more by very slightly tuning the mirrors and changing the phase.