[Tanaka, Yokozawa, Ushiba]
Figure 1 and 2 show the picture of viewport to AS table on OMC chamber with and without OMC flash, respectively.
Figure 3 shows the same figure as fig1 with marking the IR scattered light observed only when flashing OMC.
Seemingly somehow clipped probably. Because there are no dedicated beam dumps for probable weak ghost beams generated at this viewport window, you can just slightly tweak the relevant steering mirror (mirror#4 of Fig. 1 of klog27252) in the chamber so that the main OMC transmitting beam would not be clipped at the edge of this window, if possible.
[Tanaka, Yokozawa, Ushiba]
After the discussion with Akutsu-san, we tweeked the steering mirror #4 of fig1 in klog27252.
I rotated the yaw actuator by 2.5 turns not to clip the edge of the viewport.
After moving, OMC trans can pass the viewport without clipping.
Then, we moved periscope, lens, and CCD camera on AS table to detect the OMC transmission on the camera.
For their alignment, we shifted the optics by 25 mm in -Y direction.
Figure 1 shows the OMC transmission after moving the optics; it seems fine.
Note:
During the work, we noticed lens stage is fixed on the optical table with only one screw, and entire structure can easily rotate.
However, we fixed it as it was because we don't want to change the distance between CCD camera and lens.
So, please be careful to work on the OMC transmission optics.
