NAOJ GW Elog Logbook 3.2
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AkihiroTomura - 18:47, Wednesday 20 December 2017 (613)
Mode cleaner telescope 1
I measured dimensions of the green beam after Mach-Zehnder to design a telescope for a mode cleaner. One of attached pictures shows a result. The x-axis of this graph starts from the output of EOM.
An eigenmode of the mode cleaner was calculated using values and a formula shown in a picture. A cavity length was roughly estimated from the number of holes on the optical table because I could not find it in e-logbook.
Based on these information, I searched for a optimal lens pair for telescope. One example is shown in a picture. In this case, mode matching factor for vertical and horizontal axis of the beam are 99.37 % and 99.56 %, respectively.
Images attached to this report
Comments related to this report
I upload the drawings of the MC (made by Uraguchi-san) as a reference for dimensions and specs.
This is a correction of the entry 613.
In the entry 613, I made a miscalculation. This entry is a correct one.
I re-calculated optimal lens pairs for a telescope for the mode cleaner (green) with accurate dimensions (see here for the drawing). Figures attached show lens pairs that seem acceptable and the parameters I used.
In the case of the first figure, the mode matching factors are 99.718% and 99.601% for vertical and horizontal axes, respectively.
In the case of the second figure, the mode matching factors are 100% and 99.727% for vertical and horizontal axes, respectively.
The lens with 75.6 mm focal length that we already have is one without any surface coating thus low transmissivity. So I think the first case is preferable.
In the entry 613, I made a miscalculation. This entry is a correct one.
I re-calculated optimal lens pairs for a telescope for the mode cleaner (green) with accurate dimensions (see here for the drawing). Figures attached show lens pairs that seem acceptable and the parameters I used.
In the case of the first figure, the mode matching factors are 99.718% and 99.601% for vertical and horizontal axes, respectively.
In the case of the second figure, the mode matching factors are 100% and 99.727% for vertical and horizontal axes, respectively.
The lens with 75.6 mm focal length that we already have is one without any surface coating thus low transmissivity. So I think the first case is preferable.