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Interferometer Layout for Both IR and Green Beams, With and Without ITMs

JGW-T1807775. October 23, 2019. Interferometer Layout for Both IR and Green Beams, With and Without ITMs. Yuta Michimura Department of Physics, University of Tokyo. Sapphire ns=1.754 for 1064 nm ns=1.772 for 532 nm Fused Silica nf =1.450 for 1064 nm nf =1.461 for 532 nm Lengths

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Interferometer Layout for Both IR and Green Beams, With and Without ITMs

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  1. JGW-T1807775 October 23, 2019 Interferometer Layout forBoth IR and Green Beams,With and Without ITMs Yuta Michimura Department of Physics, University of Tokyo

  2. Sapphire ns=1.754 for 1064 nm ns=1.772 for 532 nm Fused Silica nf=1.450 for 1064 nm nf=1.461 for 532 nm Lengths Larm=3000 m Lmx=26.6649 m Lmy=23.3351 m Lp3=15.7386 m Ls3=15.7386 m Ltms=8.3 m Default by IR ETMY 0.05deg ITMY 0.025deg PR3 BS 0.08deg ITMX 0.025deg ETMX 0.05deg SR3

  3. xt=x-Ltms*sinθyt =-0.0131 m IRFull θyt=arcsin(ns*sinwETM)-wETM =658 urad Calculation consistent with default layout at 10-4 m level This can be derived from wBS and wITM. Assuming BS incident angle to be ~π/4, θbs=arcsin(nf*sin(arcsin(sin(π/4)/nf)+wBS))-wBS-π/4)/2-θy = (a-1)*wBS/2-θy, where a=√(nf2-sin2(π/4))/cos(π/4) ETMY 0.05deg yp=Lp3*sin(θin) =0.0122 m x=-Lmy*sin(θy) =-0.00768 m ITMY 0.025deg θbs’=134.987226891 deg =135 deg-θbs θy=arcsin(ns*sinwITM)-wITM =329 urad ybs=-dBS/cos(θr)*sin(θox) =-0.0250 m PR3 θxt=arcsin(ns*sinwETM)-wETM =658 urad BS 0.08deg θin=θy+2*θbs =775 urad θoy=π/4-θbs-θr =15.818 deg yt=y-Ltms*sinθxt =-0.0217 m θr=arcsin(sin(π/4-θbs-θy)/nf) =29.169 deg ITMX 0.025deg ETMX 0.05deg y=ybs+Lmx*sin(θx) =-0.0162 m xbs=dBS/cos(θr)*sin(θoy) =0.0250 m θx=arcsin(ns*sinwITM)-wITM =329 urad θs=π/4-θbs-wBS-arcsin(nf*sin(θr-wBS)) = 1429 urad SR3 θox=π/4+θbs-θr =15.844 deg xs=xbs+Ls3*sin(θs) =-0.0475 m

  4. Δxt ~ -Ltms*Δθyt =-6.9 um (so small) IRw/o ITMs Beam position change at TMS will be very small (even if there is no ETM). 3 km arm assures tiny incident angle to ETM. Δθyt~ Δθey =0.833 urad See JGW-T1807652 for calculation except for TMS ETMY 0.05deg Δθey~Δx/Larm = 0.833 urad Refraction angle by BS wedge stays the same; θbsr ~ (a-1)*wBS, where a=√(nf2-sin2(π/4))/cos(π/4) =1103 urad Δx~Lmy*Δθin-Δox =-0.00250 m ITMY 0.025deg Δθex~Δy/Larm = 4.65 urad PR3 BS 0.08deg To compensate no wITM Δθin~θx = 329 urad Δθxt ~ Δex = 4.65 urad Δyt ~ Ltms*Δθxt = 38.6 um (so small) Δox~Δoy~Lp3*δθin = 0.00518 m ITMX 0.025deg ETMX 0.05deg Δy~(Lp3+Lmx)*Δθin = 0.0140 m Compared with IR Full SR3

  5. from PR, aligned to both ends Greenw/o ITMs IR at both ends and green from PR going to both ends are not compatible ETMY 0.05deg Δθey~Δx/Larm = 0.0629 urad Refraction angle by BS wedge changes. θbsr532 ~ (a532-1)*wBS where a=√(nf5322-sin2(π/4))/cos(π/4) θbsr532 ~1128 urad Δx~Lmy*Δθin-Δox =-0.00019 m ITMY 0.025deg Δθex~Δy/Larm = 0.351 urad PR3 To compensate θbsr change, Δθin ~ θbsr532-θbsr = 24.9 urad BS 0.08deg Δox~Δoy~Lp3*Δθin = 0.00039 m ITMX 0.025deg ETMX 0.05deg Δy~Δoy = 0.00039 m Compared with IR w/o ITMs SR3

  6. from PR, aligned to IR beam Greenw/o ITMs IR at both ends and green from PR going to both ends are not compatible ETMY 0.05deg ITMY 0.025deg PR3 BS 0.08deg ITMX 0.025deg ETMX 0.05deg Δye=(Larm+Lmx+Lp3)*(θbsr532-θbsr) =0.076 m Compared with IR w/o ITMs SR3

  7. Green XFull ETMY 0.05deg Δyp ~ -Δox+Lp3*Δθin = 0.00006 m ITMY 0.025deg Δθxt=θxt532-θyx ~ (ns532-ns)*wETM =15.7 urad PR3 BS 0.08deg Δθin=-Δθx+θbsr532-θbsr =16.997 urad Δyt=-Ltms*Δθyt =-0.00013 m Δox~Δoy~Lmx*Δθx = 0.00021 m ITMX 0.025deg ETMX 0.05deg Δθx=θx532-θx ~ (ns532-ns)*wITM =7.85 urad Compared with IR Full SR3

  8. Δxt=-Ltms*Δθyt =-0.00013 m Green YFull Δθyt=θyt532-θyt ~ (ns532-ns)*wETM =15.7 urad ETMY 0.05deg ITMY 0.025deg PR3 Δθy=θy532-θy ~ (ns532-ns)*wITM =7.85 urad BS 0.08deg Δox~Δoy~Lmy*Δθy = 0.00018 m ITMX 0.025deg ETMX 0.05deg Δθs=Δθy+θbsr532-θbsr =32.705 urad Compared with IR Full Δxs ~ Δox+Ls3*Δθs = 0.00070 m SR3

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