(Sheila, Alexa)

See D1201448 for reference. 

We inserted ALS-L1 (ROC=75mm), which we had temporarily removed. Then, with the Mode Master (silicon detector), we spent the day mode matching the telescope along the green path (ALS-L6 and ALS-L7), which were placed for the OAT configuration and not the nominal configuration.

First, we examined the beam profile with the table in the OAT configuration and the mode master 28.5inches from ALS-M11. Image 'OneArmTextEndX' portrays the result. We subsequently removed ALS-L6 (ROC=-100mm) from the path and took another beam profile with the mode master in the same position. Image 'OneArmNoLens' portrays the resullt. We used this data to determine the seed waist of the beam. This seed waist matched that of the optical layout. We proceeded to create an "a la mode" matlab script to determine the proper positions of L6 and L7 with the target waist size of 2.2mm at 184.6inch from M11. Note: the target wasit size was determined via T1200200; the location was determined by measuring the distance from the TransMon secondary mirror to the chamber viewport (TransMon layout (D0902163, D1201457) and assuming the TransMon chamber was 2ft from the ALS table. We determined that L7 was 7inch from M10 and that L6 was 37inch from L7. This gave us a 99% overlap.

In this nominal configuration, we placed the mode master 660mm from M11 (we wanted to better stablize the MM). We noticed that the MM kept giving different results. Images 'ISCEXMM660mm2M11...' are snaptshots of four runs of the beam profile with everything in the exact same position. We were a bit unsure why the MM kept giving such different results. The waist size seemed close enough to 2.2mm; however, the location was drasitically off. We concluded for the day in this puzzled state...(more work tomorrow)

I have also attached the matlab script.