J. Freed, J. Kissel, J, Wright,

Continuing from 90645(Notes are stored here). Today we calibrated the picos on M_M1 and M_C1, got the beams centered on both QPDs, saw our first beat notes in the Meas IFO.

In order we did:

• Calibrated the picos on M_M1 both with physical distance and power read on the QPD1s quadrants
• Centered the the beam on QPD1
• Used the M_C1 picos to center the beam on M_M5
• Manually Adjusted M_M5 to send the beam towords the center QPD2. This was a difficult process as:
  • The "shelf" which is the back rest that the 45 degree adaptor uses when it attaches to the mirror mount is small and hard to get a feel for. This means that when we adjust the 45 degree adaptor manually to direct the laser light at the QPD, its hard to adjust to the correct angle for the light and make it flush with the shelf. The result we eventually got to work infack looks like this Periscope_Alignment.jpg. Where M_M5 is on the left and the 45 deg adaptor sits crooked in it. 
  • The QPD quadrents would saturate well before the beam was fully on a quadrent. This made estimating where the light was on a quadrent difficult 
  • There is no fine adjust except for 1 degree of freedom from the mirror mount knobs. And that degree of freedom is diagonal across the QPD plane. Both knobs move the beam across this diagonal. Our strategy that worked was to put the light fully in one quadrant and move the knobs in the diagonal direction towards the center. It did work after a few attempts.
• Used the M_C1 Picos to make the last fine adjustments. Of course the light is no longer center on M_M5 Beam_on_M_M5.jpg.
• Calibrated the picos on M_C1 both with physical distance and power read on the QPD2s quadrants
• Saw the first beat nots on the Meas IFO