►Folding mirrors

We use 2inch mirrors (d2" x t3/8") mirrors for the PRC/SRC folding mirrors.

Their name has been changed such that the definition agrees with the AdvLIGO naming. (12/01/2009)

New PR3/SR3 mirrors (delivered Feb 7th, 2019)

Design Specification E1800089

RoC = 1000 m +/- 150 m
Sagitta = 0.323 um
Diameter 2" x Thickness 10 mm 2deg wedge (horizontal)
Super polish <1 angstrom RMS
Coating S1: AOI 40-45 @41.1 T<50ppm@1064nm, p-pol
Arrow marking at the thickest side

Specification of the delivered optics

Substrate Spec: AdvancedGlassIndustries.pdf

Polish Spec: CoastlineOptics.pdf

Serial	S1 RoC	S1 RMS	S2 RoC	S2 RMS
REV 7-1	-976.7 m	0.69 Å	31091.0 m	0.37 Å
REV 7-2	-1002.0 m	0.40 Å	21079.3 m	0.41 Å
REV 7-3	-1002.6 m	0.83 Å	18876.4 m	0.38 Å
REV 7-4	-1023.8 m	0.38 Å	10855.1 m	0.74 Å
REV 7-5	-1004.6 m	0.49 Å	9556.2 m	0.71 Å

Coating Spec: FiveNineOptics.pdf

S1 T: P-pol 40deg 35.1 ppm / 45deg 94.1 ppm
S2 R: P-pol 40deg 889.1 ppm / 45deg 245.3 ppm

Zernike Polynomial Z₂⁰ = 1-2 rho², where rho is the normalized radius (rho = r/r₀). Define z₂⁰ as the coefficient for this term. ("Power" in Zygo data is defined as zygo = 2*z₂⁰)

Sphere z=(R²-r²)^1/2 => R [1- (r/R)²/2] for a small r.

Comparing the second order terms, we obtain: zygo/ r₀ = 1/(2 R) => R = -r₀^2/2/z,,2,,0^

Use r,,0=40.64mm/2 and Lambda = 633nm => R=326.147/zygo where R is RoC

Serial	S1 RoC	S2 RoC
REV 7-1	0.354 λ => -921 m	-0.028 λ => 12 km
REV 7-2	0.337 λ => -968 m	-0.024 λ => 14 km
REV 7-3	0.339 λ => -962 m	-0.041 λ => 8.0 km
REV 7-4	0.330 λ => -988 m	-0.044 λ => 7.4 km
REV 7-5	0.349 λ => -935 m	-0.047 λ => 6.9 km

Specs of the folding mirrors (as of Dec 16, 2009)

Name	PR2	PR3	SR3	SR2
Size	2"dia. X 3/8" thick	2"dia. X 3/8" thick	2"dia. X 3/8" thick	2"dia. X 3/8" thick
Incident angle	2.5 deg	36.5 deg	44 deg	6 deg
HR Transmission 1064 nm	500ppm	< 100 ppm	< 100ppm	< 100ppm
AR Reflection 1064 nm	< 0.25%	< 0.25%	< 0.25%	< 0.25%
ROC	Flat	Flat	Flat	Flat
Wedge angle	1 deg	1 deg	1 deg	1 deg
Qty.	2	2	2	2