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The Laser Box position on SOAR
At 67.5Deg from IR Nasmyth
IR
Nasmyth
Optical
Nasmyth
Note: Laser umbilical cord of 7m has been tested. It can be laid out along the
elevation ring passing directly to the cable ladder on the Nasmyth bearing and
under the IR Nasmyth platform (tb/re-checked by SOAR team).
SAM LGS-v1, Optics, 220507
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The LGS system
M6
S-B-C
M2
B-E
L
a
s
e
r
M3
M1(pupil)
22.5deg
M4
M5
M3
M6
Laser Box:
Beam Propagation:
Launch Telescope
Laser: JDSU Q301-HD
Laser-line (broad band?) Mirrors
B-E: Special Optics 61-30-2-8x-351
CA-in=10mm,out=30mm, $2450.
Diameter=30mm, R~99%.
M1: R=1000mm, C=-0.970454,
F=300mm.
M2: R=30mm, C=0, F=9mm.
S-B-C: Special Optics 8-500-UV-25
CA=25mm, $4150.
SAM LGS-v1, Optics, 220507
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The Laser beam and Spot Characteristics
Laser Beam Quality: M²<1.2  TEM00 purity better than 90%
Waist (TEM00)=0.13mm
B-E magnification = 4x, places parallel beam waist =4mm on LLTM2.
LLT magnification = 33.32x places waist image = 39.4mm at 10km.
Mixed Mode results for M2 = 1.2000:
Sur
Size
Waist
Position
Radius
Divergence
Rayleigh
LLTm2 44 2.14217E+000 2.14217E+000 -4.27749E-004 -2.67736E+012 6.33003E-005 3.38414E+004
LGS IMA 1.97396E+001 1.97396E+001 -5.87887E-003 -1.40456E+015 6.86944E-006 2.87354E+006
Note: B-E of 8x degrades LGS IQ (though still diffraction limited) but has
the advantage of lower energy density on beam propagation mirrors.
SAM LGS-v1, Optics, 220507
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Polarization Strategy
Laser Linear l/4 Nasmyth Circular l/4 Linear WFS module
Expected Residual Ellipticity: de-phase in SAM common path (tb/measured).
polarization
p=p/2
phase=p
1
phase=2p-p/10
0.5
0
-1
-0.5
0
0.5
1
-0.5
-1
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LGS delivery System Tolerances
LGS delivery system Tolerances
Surface Shape
Component
Conic
Displacement
Tilt
Radius
Max. Dr
Max. DQ
(mm)
(mm)
(Deg)
B-E
---
---
1.288
0.0164
m6
---
---
2.137
0.0073
m5
---
---
5.660
0.0072
m4
---
---
2.968
0.0178
m3
---
---
6.572
0.1029
LLTm2
---
0.1
0.073
0.1390
LLTm1
1.08E-04
0.2
0.073
0.0042
LLT
---
---
2.131
0.0086
Max.DZ (tolerance on m1-m2 distance) = 7.25um
SAM LGS-v1, Optics, 220507
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SOAR flexure: LLT Tilt and Decenter
(the effect on image shift and quality)
2.3mm
1.3min
2.3Arcsec
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Displacement and Tilt correction
Input beam angle=+0.0134Deg; corrects
+2.3mm of LLT displacement.
LLT M1 tilt angle=-0.894Arcsec; corrects
2.3Arcsec of image shift.
0.894”=2.167um actuator push-pull
Conclusion: M6 and M4 motorized tip-tilt for easier alignment.
Beam Active control: 4 diodes at the edge of LLTM1 close loop on M4.
SAM LGS-v1, Optics, 220507
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To Do List
• Define the beam transfer Mirrors now!.
• The Alignment Plan and alignment tools.
• Finish the Laser Box design (beam quality control and alignment gadgets).
• The Optical Component List for PO.
• The Documentation for PDR.
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