I also attached the view image on CAD data by Hirata-san. In this image, the baffle in front of PR2 was not set.

According to this data, The viewport above the main tube can be better for seeing the center of PR2. According to the photo, this port has a viewport.

Oshino kun activated the GigE camera at PR2. Image1 shows image without no bckground visible light, image2 shows the image with bckground visible light.

Some spots and scattered light in the image1 seemed to be optical lever light, not green beams because no changes happened when the green beam was shut. Of course, no IR can be found even if I set the max exposure.

For your reference, the view from the viewport windows in several locations are shown by Hirata-san. See JGW-T2113302.

Based on Miyoki-san's request, I manually evaluated the center and radius of the elliptic for the PR2 mirror.

I fitted the mirror edges (where Miyoki-san thought they were) by elliptic manually and overlayed the best-fit elliptic on the image.

I have attached the two examples. Both elliptics have the same center and long diameter but a different short diameter. This time I didn't take care of the rotation of the elliptic.

Miyakawa-kun is now selecting a camera that is like T-cam camera instead of the GigE cam at PR2.

I removed the GigE camnera at the PR2 and used another camera ASI294MC which is being used as Tcam and has a good sensitivity for IR.

I could see the IR spot. The white area in Fig.1 circled by Magenta lines comes from IR light since RGB has the same response above IR wavelength. Today, all the suspensions are in safe mode, so the IR spot was hitting somewhere from the center of the mirror.

The purpose of this new camera is to see the scattering IR light clipped by baffles or something during lock. In this meaning, This camera meets the requirements.

I saw a lot of red light from Oplev, but I did not see green light coming from the green laser. Even direct watching by my eye, I saw only red light and I did not see the green light at all.

The focal length of this lens was a bit too long, so the area we can see is a bit small. Comparing Fig.2 and Fig.3 can help to identify where it is. Both are exactly the same angle.

Today's camera and lens are just a test version, I need to prepare another filter or shorter focal length lens. I will order a proper camera and lens and some adapters. I put the GigE camera back today. When the new camera is ready, I will install it.