YuhangZhao - 01:31, Saturday 02 December 2017 (608)
Finding the infrared beam
I'm trying to find the infrared beam during these two days. I was trying to find it in-between two half of the halos.
Firstly, about the losing of the camera of the second target(or irises or aperture). I checked the link and cable. I also changed the driver for this camera. All of them didn't bring back our camera. But I found there was a gap on the case of camera.(As you can see in the figure one.) Maybe this is one reason, so I will check its capability further more.(Since we can see the scattered light or halo, I think there is no need to use the second irises. But brining it back will be a good thing for the future.)
Secondly, about the cable in the end room. I almost stumble because of the cable around the end room's bench. The reason is one of the cables is really short, which makes it suspended away the ground. And this happened on Thursday. On Friday, I cannot find the transmitted signal from the end mirror. I checked many things and finally realized where the problem would be. If you read previous part carefully, you can see the problem comes from the short cable. It causes the misalignment of the QPD. So I think we should do something to avoid this happens again.
Thirdly, I can find something really similar with yuefan's previous infrared beam gazing. You can find the video I took from the link in the bracket. But I tried to change the local control offset for each mirror, finding it's really different from the behavior of green beam. For example, the changing of this possible infrared beam does't follow the changing of the local control offset very well. Sometimes it looks really like the halo after changing the local control offset. I need to confirm this strictly, but the signal here is really weak! I feel the confirmation is really difficult.
(https://drive.google.com/file/d/12OmtNB93hNnNigcgu_0SNxJNy5pxSIPq/view?usp=sharing)
Fourthly, Tomura-san found we can use the sensor card to sense the infrared beam in the end room. I used it to check the light from EM chamber output port to the camera. I found almost one third of the beam is lost because the alignment on the end room bench. So I changed the alignment a little bit. The change includes one lens, one 45 degree mirror(Actually I don't know what this mirror for) and the camera. Now we can see the whole two half of halos by changing the angle and height of camera. You can see the video by clicking the attached link as following.
(https://drive.google.com/file/d/1MsWtaURQJLrXH1PSE4-g_qudrmI73w9c/view?usp=sharing)
Fifthly, Tomura-san suggested there is possibility that something is blocking on the infrared. Because you can see a black line in the spot of reference infrared beam. But I check the layout of our experiment, it's not the beam sending to cavity. However, the reference which is sending to cavity has also something like defect. The defect is the combination of a small spot and a larger spot. It's really like the scenario we can see from the infrared transmitted signal of EM, where there is a bright halo and a darker halo.(You can see this combination from the second video)
Sixthly, I checked the bright halo by changing the local control offset. As you can see from the attached second and third photo, there is angle changing of halo. And the halo is flashing. I suspect this halo can be the what we want to find. I will try to figure it out soon.
In the end, I can ride the bicycle very well now! I need to go to end room and go back many times to find the signal, which drives me to ride bicycle many times. This is really an useful skill and a good way to calm down or feel balance. &( ^___^ )&
Firstly, about the losing of the camera of the second target(or irises or aperture). I checked the link and cable. I also changed the driver for this camera. All of them didn't bring back our camera. But I found there was a gap on the case of camera.(As you can see in the figure one.) Maybe this is one reason, so I will check its capability further more.(Since we can see the scattered light or halo, I think there is no need to use the second irises. But brining it back will be a good thing for the future.)
Secondly, about the cable in the end room. I almost stumble because of the cable around the end room's bench. The reason is one of the cables is really short, which makes it suspended away the ground. And this happened on Thursday. On Friday, I cannot find the transmitted signal from the end mirror. I checked many things and finally realized where the problem would be. If you read previous part carefully, you can see the problem comes from the short cable. It causes the misalignment of the QPD. So I think we should do something to avoid this happens again.
Thirdly, I can find something really similar with yuefan's previous infrared beam gazing. You can find the video I took from the link in the bracket. But I tried to change the local control offset for each mirror, finding it's really different from the behavior of green beam. For example, the changing of this possible infrared beam does't follow the changing of the local control offset very well. Sometimes it looks really like the halo after changing the local control offset. I need to confirm this strictly, but the signal here is really weak! I feel the confirmation is really difficult.
(https://drive.google.com/file/d/12OmtNB93hNnNigcgu_0SNxJNy5pxSIPq/view?usp=sharing)
Fourthly, Tomura-san found we can use the sensor card to sense the infrared beam in the end room. I used it to check the light from EM chamber output port to the camera. I found almost one third of the beam is lost because the alignment on the end room bench. So I changed the alignment a little bit. The change includes one lens, one 45 degree mirror(Actually I don't know what this mirror for) and the camera. Now we can see the whole two half of halos by changing the angle and height of camera. You can see the video by clicking the attached link as following.
(https://drive.google.com/file/d/1MsWtaURQJLrXH1PSE4-g_qudrmI73w9c/view?usp=sharing)
Fifthly, Tomura-san suggested there is possibility that something is blocking on the infrared. Because you can see a black line in the spot of reference infrared beam. But I check the layout of our experiment, it's not the beam sending to cavity. However, the reference which is sending to cavity has also something like defect. The defect is the combination of a small spot and a larger spot. It's really like the scenario we can see from the infrared transmitted signal of EM, where there is a bright halo and a darker halo.(You can see this combination from the second video)
Sixthly, I checked the bright halo by changing the local control offset. As you can see from the attached second and third photo, there is angle changing of halo. And the halo is flashing. I suspect this halo can be the what we want to find. I will try to figure it out soon.
In the end, I can ride the bicycle very well now! I need to go to end room and go back many times to find the signal, which drives me to ride bicycle many times. This is really an useful skill and a good way to calm down or feel balance. &( ^___^ )&
Images attached to this report
