With Hirata-san.

See pictures of the day in the PR2 Remedying Work album.

In the context of setting the pitch of PR mirrors to nominal values (±1/300 rad) we measured the deviation of two laser levels with distance. We used the method described in this link.

• Hitachi UG 20UA: 13.5 mm over 5 m (manufacturer's specification is ±1 mm over 5 m).
• Tajima Zero: 0.75 mm over 7.5 m (manufacturer's specification is ±1 mm over 7.5 m).

Observations:

• The Tajima one is within the specification.
• The Hitachi one is really bad. It's fine to use it in an oplev for relative angular displacement but not for measuring with respect to the horizontal plane.
• Some parts of the body of the Hitachi laser level are broken. It seems like it was accidenttally dropped on the floor. See this picture, for example.
• As can be seen in the pictures, we used pen on white board for making marks where the laser level was, and a ruler with milimeter scale, so there's uncertainty in the measurement, but it's fine of our purposes.