[Fujii, Akutsu]

We covered the optical components for PR3's oplev reside outside of the chamber by wind shields.

(1) We firstly tried to adjust the incident angle of the oplev's beam, but after some efforts we found the position and alignment of the light source was the best from the first; at least we cannot find better setup.

(2) Then the light source was covered by the wind shield. As this oplev is not folded type, the QPD and the light source are on different tables. For the QPD, due to is footprint and the current position, the wind shield cannot be set, so we just set a duct from the viewport flange to the QPD.

(3) At the first time, the QPD was covered with some aluminum foils as well as the duct describerd above. But after a short investigation, the aluminum foils would cause strange (probably electronic) noise on the QPD circuit (probably it touched the circuit.)

(4) The measurements were done three times; (i) right before any wind shiedling today [REF0, REF1], (ii) after both of the light source and the QPD were coverd [REF2, REF3], and (iii) after the aluminum foil covering the QPD was removed. Fig.1 shows the results, and it seems (iii) shows the best performance.

(5) Longer measurements were done after we were out of the clean booth, and the result is shown in Fig. 2 with the rms values.

So far the (half) wind shielded oplev seems to meent the requirements.