Space Qualification of the Optical Filter Assemblies for ...
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1 Goddard Space Flight Center SPIE LASE 2015 – 9346-16 Space Qualification of the Optical Filter Assemblies for the ICESat-2/ATLAS Instrument Elisavet Troupaki*, Zachary Denny, Stewart Wu, Heather Bradshaw, Kevin Smith, Judy Hults, Luis Ramos-Izquierdo, William Cook * [email protected] https://ntrs.nasa.gov/search.jsp?R=20160000227 2019-08-31T04:34:02+00:00Z
Transcript of Space Qualification of the Optical Filter Assemblies for ...
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Goddard Space Flight Center
SPIE LASE 2015 – 9346-16
Space Qualification of the Optical Filter Assemblies for the
ICESat-2/ATLAS Instrument
Elisavet Troupaki*, Zachary Denny, Stewart Wu, Heather Bradshaw, Kevin Smith, Judy Hults, Luis Ramos-Izquierdo, William Cook
https://ntrs.nasa.gov/search.jsp?R=20160000227 2019-08-31T04:34:02+00:00Z
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Goddard Space Flight Center
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ATLAS Measurement Concept (slide provided byAnthony Martino, ATLAS Instrument Scientist)
Transmitter
Telescope Filter
& Optics
Atmosphere
Surf
ace
4 x 1014 transmitted signal photons 3.5 x 1014
3.4 x 1014 2.9 x 1014
280
Detector
12 detected signal photons/shot
6 x 106 detected background photons/sec
ATLAS reports times of laser firings and photon detections to the ground. Range and surface elevation are computed by data processing on the ground.
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Advanced Topographic Laser Altimeter System
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Goddard Space Flight Center
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ATLAS Receiver Diagram
The Receiver collects light from the target, filters out most of the solar background, and generates electrical signals corresponding to the arrival of individual photons in each of the 6 spots.
Telescope
Scattered light from 6 spots + solar background
Aft Optics Focal Plane
Optical Filter Assembly
Detector Optics
Detector Array Assembly
Primary Detector Modules
Redundant Detector Modules
Detector Select
6 fibers
6 fibers to Avionics
from Laser Sampling Assembly
to TAMS LTR
TAMS Source
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ATLAS Optical Filter Assembly
The ATLAS OFA shall: ü remove background solar radiation from collected signal while transmitting the laser light to the detectors ü provide the means to monitor the etalon tuning to the laser wavelength
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Goddard Space Flight Center
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ATLAS Optical Filtering Modules
beam splitter cubes collimating lens focusing lens
etalon coarse filter BCE RTA test port
BCE DAA test port
Input AVIMS adapter Output AVIMS adapter
Envelope: 7.67” x 3.76” x 2.44” Materials • Optics: Fused Silica • Body: Ti-6Al-4V • Spacers/Retaining Rings – Ti-6Al-4V • Thermal Compensators – Al 6061
test port lenses
wave spring
wave spring
wave spring
retaining ring
retaining ring
retaining ring thermal compensator
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ATLAS Wavelength Tracking Optical Module
!
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Optical Performance (filters)
Parameter Specification Performance Center Wavelength 532.272 nm +/- 0.012nm
in vacuum, at 40°C 532.264 nm – 532.283 nm
Free Spectral Range 300 +/- 3pm 297.6 pm - 299.9 pm Passband full width 30 +/- 2 pm at 50% of measured peak
transmission 27.73 pm - 28.80 pm
Peak transmission > 90% 96.01% - 98.20%
Measured performance of the 18 flight etalon filters
Measured performance of the 20 flight blocking (coarse) filters
Parameter Specification Performance Center Wavelength 532.272 nm +/- 0.040nm,
at 40°C, in vacuum 532.245 nm – 532.285 nm
FWHM 200 +/- 40 pm 184.0 pm – 195.7 pm Peak transmission >80% 82.2% - 90.3%
Out-of-band blocking OD5 from 250nm to 950nm OD5 or better
0"
0.2"
0.4"
0.6"
0.8"
1"
531.9" 532" 532.1" 532.2" 532.3" 532.4" 532.5"
Etalon(4.1)"@"40.7C"Filter(10;1)"@"40.7C"
0"
0.2"
0.4"
0.6"
0.8"
1"
531.9" 532" 532.1" 532.2" 532.3" 532.4" 532.5"
Etalon(4.1)@20.3C"Filter(10;1)@20.3C"
!
Etalon and filter transmission vs. wavelength at room temperature (left) and at mission operating temperature (right)
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Goddard Space Flight Center
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Optical Performance (filter assemblies)
Parameter Requirement Performance Optical transmission 64.4% 71.2% - 78.7% (lab single-mode
tunable 532nm laser); Bandwidth (FWHM) 30 ± 3 pm 31.04 – 32.35 pm Center wavelength (vacuum) 532.272nm 532.272 nm, at nominal operating
temperature Wavelength tunability greater than ± 15pm greater than 25pm Solar background rejection transmittance of no more than 8.5E-
5% integrated across the solar spectrum
3.7E-5% - 8.5E-5% broadband transmission between 250nm and 950nm
Light tightness Stray light events of no more than 2KHz light
<500Hz (lab)
0"
0.1"
0.2"
0.3"
0.4"
0.5"
0.6"
0.7"
0.8"
0.9"
1"
532.1" 532.15" 532.2" 532.25" 532.3"
OFA0A"Meas."Transmission"@"20.3C"OFA0A"Est."Transmission"@"20.3C"OFA0A"Est."[email protected]" !
Estimated and measured optical throughput of OFM #A
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Vibration Testing
Type of testing Axis Protoflight Level Sine Burst X, Y,
Z 15G, 5 cycles conducted at 25Hz
Swept Sine Vibration
X, Y, Z
0.63 inches D.A. (5-19.7Hz, 4 oct/min sweep rate)
12.5G (19.7-50Hz, 4oct/min sweep rate)
Test levels for sine burst and swept sine vibration tests
!
Random vibration levels for x and y axis (left) and z axis (right)
No change in optical transmission or peak wavelength after vibration testing
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Thermal – Vacuum Testing
In#Air'Test:'Step'1'
In#Air'Test:'Step'2'
Chamber'Pumpdown'
Cold'Survival'Soak'
#15pm'Test'
'Nominal'Balance'
+15pm'Test'
High'Power'Balance'
Hot'survival'soak'&'
bakeout'
Cleanliness'Cert'
Chamber'Break'
Cold'qual'soak'1'
Hot'qual'soak'1'
Cold'qual'soak'2'
Hot'qual'soak'2'
Cold'qual'soak'3'
Hot'qual'soak'3'
Return'to'Ambient''
!30$
!20$
!10$
0$
10$
20$
30$
40$
50$
60$
70$
Tempe
rature'(C
)'
OFA'TVAC'Test'Profile'
Air$ Vacuum$
0"
0.05"
0.1"
0.15"
0.2"
0.25"
0.3"
0.35"
0.4"
0.45"
)20"
)10"
0"
10"
20"
30"
40"
50"
60"
70"Transm
ission)(a.u.))
tempe
rature)of)e
talon)ho
using)(deg)C))
Time)
)Op8cal)transmission)in)vacuum)
Temp)
Transmission)
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Performance in Vacuum Etalon'Housing'Temp='38.2'C'
0'
10'
20'
30'
40'
50'
60'
70'
80'
532.230' 532.240' 532.250' 532.260' 532.270' 532.280' 532.290' 532.300' 532.310' 532.320'
Op#
cal'Throu
ghpu
t'(%)'
Transmi6ed'wavelength'(nm)'
OFM'#B'
Optical throughput in vacuum (OFM)
Optical throughput in vacuum (WTOM)
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Goddard Space Flight Center
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Center Wavelength
!
Wavelength Tunability (temp coeff=3.6pm/°C)
Center wavelength data before and after vibration and thermal-vacuum tests
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BACKUP SLIDES
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Goddard Space Flight Center
SPIE LASE 2015 – 9346-16
Matching the ATLAS laser center wavelength…
² Etalon and filter peak transmission wavelength (same as ATLAS center wavelength, specified by ATLAS laser vendor in July 2012) :
532.272nm at 40°C in vacuum
² For any calculation of the index of refraction of air and/or vacuum, the following calculator shall be used: http://emtoolbox.nist.gov/Wavelength/Ciddor.asp assuming standard atmospheric pressure
² PO awarded for one reference/test etalon to be measured by both OFA and Laser groups
² Coarse filter sample was sent to etalon vendor in February 2013, who confirmed peak transmission wavelength (in vacuum) of 532.272nm at 40°C.
λ"Peak"Transmission"
Wavelength"Measurement"
"(Etalon"vendor"–"O;awa,"Canada)"
Peak"Transmission"Wavelength"Measurement""(Coarse"Filter"vendor"–"MA,"
US)"
Peak"Transmission"Wavelength"Measurement"
"(OFA"lab"E"GSFC)"
Laser"Peak"Wavelength"Measurement"
"(Fibertek"–"VA,"US)"
Laser"Peak"Wavelength"Measurement""
(Laser"lab"E"GSFC)"
