Thermal noise
- Mirror thermal noise
- Mirror coating structure damping (4枚鏡のtotal.)
mirrorcoa[f_, tm_, dcoa_, phicoa_, w1_, w2_, E0_] := 5.5*10-19*(dcoa/15*10-6)1/2*(phicoa/1.2*10-2)1/2*Sqrt[(10-2/w1)2*2+ (10-2/w2)2*2]*(tm/300)1/2*(7.24*1010/E0)1/2*(100/f)1/2;
- l:length of cavity[m], 100m.
dcoa:thickness of coating[m], 7.5*10-6.
phicoa:loss angle of coating, 4*10-4.
w1:beam radius of front mirror[m], 4.89*10-3.
w2:beam radius of end mirror[m], 8.48*10-3.
- tm:temperature[K], 300K or 20K.
E0:Young's modulus of substrate[N/m2], 4*1011.
- Mathematica関数表記(以下をmathematicaにコピペ利用可能...なはず。)
mirrorcoa[f_, tm_, dcoa_, phicoa_, w1_, w2_, E0_] := 5.5*10(-19)*(dcoa/(15*10(-6)))(1/2)*(phicoa/(1.2*10(-2)))(1/2)*Sqrt[(10(-2)/w1)2*2 + (10(-2)/w2)2*2]*(tm/300)(1/2)*(7.24*1010/E0)(1/2)*(100/f)^(1/2);
- Mirror substrate structure damping (4枚鏡のtotal.)
mirrorhomo[f_, tm_, sigma_, phimir_, w1_, w2_, E0_] := Sqrt[4*kb*tm*(1 - sigma2)*phimir/(Sqrt[Pi]*E0*2*Pi*f)]*Sqrt[1/w1*2 + 1/w2*2];
- l:length of cavity[m], 100.
- sigma:poisson ratio, 0.27.
phimir:loss angle of mirror material, 10-7 at 300K, 10-8 at 20K.
w1:beam radius of front mirror[m], 4.89*10-3.
w2:beam radius of end mirror[m], 8.48*10-3.
- tm:temperature[K], 300K or 20K.
E0:Young's modulus[N/m2], 4*1011^.
- Mathematica関数表記(以下をmathematicaにコピペ利用可能...なはず。)
- mirrorhomo[f_, tm_, sigma_, phimir_, w1_, w2_, E0_] := Sqrt[4*kb*tm*(1 - sigma^2)*phimir/(Sqrt[Pi]*E0*2*Pi*f)]*Sqrt[1/w1*2 + 1/w2*2];
- Mirror substrate thermoelastic damping
- thermoelastic dampingの周波数依存性は、ビーム径、基材の熱拡散係数で決まるcur-off frequencyの前後で変化する。
f >> cut-off frequency -> thermoelastic damping 1/f. 室温では「観測帯域」>> cut-off frequencyが一般に成り立つ.
f << cut-off frequency -> thermoelastic damping f. 低温では「観測帯域」<< cut-off frequencyが一般に成り立つ.
thelasticFreq[w_, kappa_, spheat_] := (kappa/(spheat w2/2)) (1/(2 Pi));
- w: beam radius [m],
- kappa: thermal ocnductivity [W/K/m],
- spheat: specific heat [J/K/m^3]
- thermoelastic dampingの周波数依存性は、ビーム径、基材の熱拡散係数で決まるcur-off frequencyの前後で変化する。
- Mirror coating structure damping (4枚鏡のtotal.)