FAR-IR OPTICS DESIGN AND VERIFICATION EXPERIMENTAL SYSTEM AND RESULTS Final Meeting “Far-IR Optics...
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Transcript of FAR-IR OPTICS DESIGN AND VERIFICATION EXPERIMENTAL SYSTEM AND RESULTS Final Meeting “Far-IR Optics...
FAR-IR OPTICS DESIGN AND VERIFICATION
EXPERIMENTAL SYSTEM AND RESULTS
Final Meeting “Far-IR Optics
Design and Verification”, Phase 2
27 November 2002, ESTEC, The Netherlands
Willem Jellema
National Institute for Space Research of the Netherlands (SRON)
FAR-IR OPTICS DESIGN AND VERIFICATION
OUTLINE OF PRESENTATION
• Test criteria and measurement concept
• System components
• Amplitude and phase measurement system
• Feasibility and upgrade of test facility
• Discussion of systematic errors
• Horn measurements
• Summary of as-validated test facility
• Mixer Sub-Assembly (MSA) measurements
FAR-IR OPTICS DESIGN AND VERIFICATION
TEST CRITERIA AND MEASUREMENT CONCEPT
Test criteria:
• Resolve features with a characteristic scale of 1 mm at –20 dBc
• Measurement uncertainty smaller than 3 to 4 dB at –20 dBc
• Accuracy in main-beam better than 1 dB
• Dynamic range larger than 30 dB
Measurement concept:
• Coherent narrow-band detection of output beam (phase is also measured)
• Signal chain based on harmonic mixer and phase-locked Gunn oscillator
• Field is sampled along linear cuts by a probe on a scanner system
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (1)
Corrugated horn design:• 2.5 mm aperture radius• 15.4 mm slant length• compliant with MSA optical I/F• adapted waveguide dimensions• optimised waveguide transition• optimised corrugation diameters• optimised corrugation widths• minimum return loss• low cross-polarisation• good E/H symmetry
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (2)
Pin flangewaveguide I/F
Chamferedcorrugated
horn
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (3)
Probe design:
• Flared waveguide probe
• TE10 mode + phase curvature
• Aperture of 1.0 x 1.4 mm• Slant length of 10.7 mm• Spatial resolution of ½ mm-1
• Good E/H symmetry• High polarisation purity• Insertion loss of 11 dB for MSA• Same flange design as for horn
90 45 0 45 9040
30
20
10
0
H-planeE-plane
Far-field angle (deg)
Rel
ativ
e In
tens
ity (
dB)
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (4)
Harmonic mixer and corrugated horn in MSA MSA on interface plate
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (5)
Alignment mirrors in MSA plate Alignment windows in Gunn interface plate
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (6)
Cross-hair in alignment window Gunn chain connected to scanner system
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (7)
Gunn on scanner Final assembly Alignment MSA / scanner
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (8)
Pitch alignment by shimming Roll / yaw alignment by tilt units
FAR-IR OPTICS DESIGN AND VERIFICATION
SYSTEM COMPONENTS (9)
SiC absorber around probe Absorber on MSA I/F plate
FAR-IR OPTICS DESIGN AND VERIFICATION
PHASE AND AMPLITUDE MEASUREMENT SYSTEM
Expected dynamic range is 30-40 dB / BW = 1 kHz / = 1 ms
FAR-IR OPTICS DESIGN AND VERIFICATION
FEASIBILITY AND UPGRADE OF TEST FACILITY (1)
Gunn oscillator and subharmonic mixer with modified Potter horns
FAR-IR OPTICS DESIGN AND VERIFICATION
-25 -20 -15 -10 -5 0 5 10 15 20 25-6
-5
-4
-3
-2
-1
0
[r
ad /
2]
x [mm]
-25 -20 -15 -10 -5 0 5 10 15 20 25
-50
-40
-30
-20
-10
0
ESA-TRP Contract: Far-IR Optics Design and Verification, Phase 2
Field coupling measured @ 480 GHz by scanning 2 modified Potter horns relative to each otherTest signal power 100 W, HM conversion loss -70 dB, IF detection BW of 10 Hz, S/N = 40 dB
Proof of Concept Amplitude and Phase Measurement
20 *
log
(E /
E0
) [dB
]
x [mm]
-25 -20 -15 -10 -5 0 5 10 15 20 25-6
-5
-4
-3
-2
-1
0
[r
ad /
2]
x [mm]
-25 -20 -15 -10 -5 0 5 10 15 20 25
-50
-40
-30
-20
-10
0
ESA-TRP Contract: Far-IR Optics Design and Verification, Phase 2
Field coupling measured @ 480 GHz by scanning 2 modified Potter horns relative to each otherTest signal power 100 W, HM conversion loss -70 dB, IF detection BW of 10 Hz, S/N = 40 dB
Proof of Concept Amplitude and Phase Measurement20
* lo
g (E
/ E
0 ) [
dB]
x [mm]
FEASIBILITY AND UPGRADE OF TEST FACILITY (2)
Proof of concept: amplitude and phase detection with 30-40 dB dynamic range
FAR-IR OPTICS DESIGN AND VERIFICATION
FEASIBILITY AND UPGRADE OF TEST FACILITY (3)
Upgrade: 2 HM’s + external diplexers, phase stable cables and an active IF tripler
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (1)
Systematic error sources present in system:
• Multiple reflections / standing waves
• Stability
• Convolution with probe pattern
• Alignment errors
• Linearity
• Cross-talk and spurious signals
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (2)
2 1 0 1 210
9.5
9
8.5
8
CalculatedMeasured patternFirst-order correction
z (wavelengths)
Cou
plin
g ef
fici
ency
(dB
)
Multiple reflections:
• Scattering environment small
• Standing wave between horns:
s(z) c(z) (1 + r1r2|c(z)|2exp(i2kz))
• Considering only one roundtrip
• First-order correction:
Ec = (E1 + E2exp(i/2)) / 2
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (3)
10 5 0 5 1020
15
10
5
0
E1E2Ec
First-order standing wave correction
x (mm)
Rel
ativ
e in
tens
ity (
dB)
15 10 5 0 5 10 150
0.1
0.2
0.3
0.4
0.5
0.6
0.7
E1E2Ec
First-order standing wave correction
x (mm)
Rel
ativ
e fie
ld m
agni
tude
Reduction > 10 dB
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (4)
0 1 2 3 4 5 60.97
0.98
0.99
1
1.01
Elapsed time (hr)
Rel
ativ
e fi
eld
ampl
itude
(V
/m)
0 1 2 3 4 5 640
20
0
Elapsed time (hr)
Rel
ativ
e ph
ase
(deg
)
Typically 1% / hr
Typically 5° / hr
Stability
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (5)
-0.03 -0.02 -0.01 0 0.01 0.02 0.03-80
-70
-60
-50
-40
-30
-20
-10
0Convolution with probe pattern
Example for GLAD
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (6)
Alignment errors:
• Lateral: < 25-50 m
• Axial: < 0.1 – 0.2 mm
• Tilt (pitch and yaw): < 1 arcmin
• Tilt (roll): < 0.1°
• Planarity: < / 20 @ = 625 m
• Geometry is controlled within fractions of
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (7)Receiver linearity
45 d
B
FAR-IR OPTICS DESIGN AND VERIFICATION
DISCUSSION OF SYSTEMATIC ERRORS (8)
Cross-talk / spurious:
• Spurious avoided by frequency plan
• Cross-talk between reference and detector always present
• High isolation is needed: > 80 dB
• Cross-talk < noise level (BW = 10 Hz, = 10 s)
Summary:
• Multiple reflections / standing waves biggest systematic error source
• Linear dynamic range of 45 dB with errors < 1 dB resp. 5
FAR-IR OPTICS DESIGN AND VERIFICATION
HORN MEASUREMENTS (1)
30 20 10 0 10 20 30
80
60
40
20
0
x (mm)
Rel
ativ
e In
tens
ity (
dB)
15 10 5 0 5 10 150
0.2
0.4
0.6
0.8
1
1.2
x (mm)
Rel
ativ
e fi
eld
ampl
itude
(V
/m)
Calculated and measured response for horn measured by probe
FAR-IR OPTICS DESIGN AND VERIFICATION
HORN MEASUREMENTS (2)Calculated and measured response for horn measured by probe
30 20 10 0 10 20 3014
12
10
8
6
4
2
0
x (mm)
Rel
ativ
e ph
ase
(per
iods
)
FAR-IR OPTICS DESIGN AND VERIFICATION
HORN MEASUREMENTS (3)Calculated and measured response for two identical horns
20 10 0 10 20100
80
60
40
20
0
x (mm)
Rel
ativ
e In
tens
ity (
dB)
10 5 0 5 100
0.2
0.4
0.6
0.8
1
x (mm)
Rel
ativ
e fi
eld
ampl
itude
(V
/m)
FAR-IR OPTICS DESIGN AND VERIFICATION
HORN MEASUREMENTS (4)Calculated and measured response for two identical horns
20 10 0 10 208
6
4
2
0
x (mm)
Rel
ativ
e ph
ase
(per
iods
)
FAR-IR OPTICS DESIGN AND VERIFICATION
SUMMARY AS-VALIDATED TEST FACILITY
• We carefully designed several system components
• We developed a differential phase and amplitude measurement technique
• We demonstrated the measurement concept and proved feasibility
• We performed a detailed error analysis
• We quantified the systematic error contributions
• We developed a first-order standing wave correction
• We realized a system with known errors (< 1 dB resp. 5°) within a 45 dB range
• We are compliant with all previously defined criteria, requirements and objectives
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (1)
Symmetric, +5mm
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-10 -5 0 5 10off-axis distance (mm)
inte
nsity
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (2)
Symmetric, 0 mm
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-15 -10 -5 0 5 10 15
off-axis distance (mm)
inte
nsi
ty (
norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (3)
Symmetric, -5mm
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-20 -15 -10 -5 0 5 10 15 20
off-axis distance (mm)
inte
nsity
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (4)
Symmetric, -10mm
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-20 -15 -10 -5 0 5 10 15 20
off-axis distance (mm)
inte
nsity
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (5)
Asymmetric, +5mm
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-10 -5 0 5 10off-axis distance (mm)
inte
nsity
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (6)
Asymmetric, +5 mm
0.E+00
1.E-01
2.E-01
3.E-01
4.E-01
5.E-01
6.E-01
7.E-01
8.E-01
9.E-01
1.E+00
-10 -5 0 5 10off-axis distance (mm)
field
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiemnt
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (7)
Asymmetric, 0 mm
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-15 -10 -5 0 5 10 15
off-axis distance (mm)
inte
nsity (
norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (8)
Asymmetric, 0 mm
0.E+00
1.E-01
2.E-01
3.E-01
4.E-01
5.E-01
6.E-01
7.E-01
8.E-01
9.E-01
1.E+00
-15 -10 -5 0 5 10 15
off-axis distance (mm)
field
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (9)
Asymmetric, -5mm
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-20 -15 -10 -5 0 5 10 15 20
off-axis distance (mm)
inte
nsity
(nor
mal
ised
)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (10)
Asymmetric, -5 mm
0.E+00
1.E-01
2.E-01
3.E-01
4.E-01
5.E-01
6.E-01
7.E-01
8.E-01
9.E-01
1.E+00
-20 -10 0 10 20
off-axis distance (mm)
field
(norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (11)
Asymmetric, -10 mm
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
-20 -10 0 10 20
off-axis distance (mm)
inte
nsity (
norm
alis
ed)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (12)
Asymmetric, -10 mm
0.E+00
1.E-01
2.E-01
3.E-01
4.E-01
5.E-01
6.E-01
7.E-01
8.E-01
9.E-01
1.E+00
-20 -15 -10 -5 0 5 10 15 20off-axis distance (mm)
field
(n
orm
alis
ed
)
GLAD
CODE V
GRASP
Experiemnt
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (13)
Symmetric, +5mm
-3
-2
-1
0
1
2
3
-5 -3 -1 1 3 5
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (14)
Symmetric, 0 mm
-3
-2
-1
0
1
2
3
-10 -5 0 5 10
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (15)
Symmetric, -5mm
-3
-2
-1
0
1
2
3
-10 -5 0 5 10
off-axis distance (mm)
phase
(ra
dian
s)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (16)
Symmetric, -10 mm
-3
-2
-1
0
1
2
3
-20 -10 0 10 20
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (17)
Asymmetric, +5 mm
-3
-2
-1
0
1
2
3
-5 -3 -1 1 3 5
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (18)
Asymmetric, 0 mm
-3
-2
-1
0
1
2
3
-10 -5 0 5 10
off-axis distance (mm)
pha
se (
radi
ans)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (19)
Asymmetric, -5mm
-3
-2
-1
0
1
2
3
-10 -5 0 5 10
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment
FAR-IR OPTICS DESIGN AND VERIFICATION
MSA RESULTS (20)
Asymmetric, -10 mm
-3
-2
-1
0
1
2
3
-10 -5 0 5 10
off-axis distance (mm)
phas
e (r
adia
ns)
GLAD
CODE V
GRASP
Experiment