a fisheye lens for many-point pdv
TRANSCRIPT
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
A Fisheye Lens for Many-Point PDV
Brent Frogget National Security Technologies, LLC
This work was done by National Security Technologies, LLC, under
Contract No. DE-AC52-06NA25946 with the U.S. Department of Energy.
DOE/NV/25946--1363
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2 in Optical Dome
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye Lens Features
11:19:58
f23crev
Scale:
7.50
BCF 30-Mar-11
3.33 MM
16:02:33
f30k (fisheye lens)
Scale:7.50
Positions: 1-2
BCF 27-Sep-11
3.33 MM
Prototype Build 2 High angular coverage Index matching element to fibers
Hemi 2 lenses Better anti-reflection coatings Cut down lens element diameters Not using highest angles
(View direction in later slide)
Index matching lens element
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye with Reflector Prisms 16:49:38
f30e (NSS hybrid fisheye)
Scale:7.50
Positions: 1-6
BCF 04-Oct-11
3.33 MM
Focus adjustment
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye Fiber Map
Hemi 2 250-micron spacing not fully populated
Index matching lens element
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Footprints of Beams
11:50:22
f30e (NSS hybrid fisheye)
SURFACE18:prism mirror
BCF28-Sep-11
1.50
MM
X=0.000
Y=0.000
Right prism mirror face
Top of fisheye lens element (only half of points shown)
100º 90º
13:42:00
f30e (NSS hybrid fisheye)
SURFACE15
BCF11-Aug-11
2.50
MM
X=0.000
Y=0.000
Hemi 2 250-micron spacing
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye Rough-Angle Metrology
This measurement inside a dome is vertically flipped compared to the spherical plot from the top (outside) on the next slide.
Symbol key
= rough area blocked
by prism mirror
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Used Locations in Spherical Plot with center as ‘up’
Doubled points are both pin measurement machine and rough metrology (uncorrected)
120
90
0 0
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye Lens
• Disadvantages – This lens type has some distortion at the edge of the
field-of-view. This causes a change in measurement point spacing with angle―high-angle spots become elliptical and less efficient. Therefore, mirrors were added for better high- angle spots causing some ‘dead’ regions.
– The fiber plane is larger than standard array connectors and is custom made.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye Lens
• Advantages – A ‘fisheye’ lens can image measurement points over greater
than a hemisphere without ‘dead’ regions.
– The front fisheye element does not encroach much into the center of the cavity allowing for longer tracking distances.
– This design uses an index matching element to keep all fibers at the same plane without high return loss.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Data Quality
• Static back-reflections (minimum, mean, maximum in dB): – <–70, –58, –46 without target (out of 44 used fibers;
two at –27 not used) – –58, –45, –33 with target
• Burn paper spot sizes: – 10 mm away: ~280-micron diameter – 50 mm away: ~320-micron diameter – 90 mm away: ~400-micron diameter
• Focus adjusted for entire probe at once
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Lessons Learned
• Good 1550-nanometer anti-reflection coatings needed on lenses.
• Index matching gel works better for us than index matching epoxy.
• Fiber polishing for coupling to index matching element is sensitive.
• Focusing to best position is sensitive and best done actively using
an IR camera.
• Highest angle points are less efficient unless reached using mirrors.
• Some areas require fibers closer together.
• We have cut down the lens diameters to fit the small blast tube.
• We can put the fiber bundle through the blast tube before attaching
it to the lenses so fiber connectors do not need to be cut.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Next Iteration
• Slightly smaller top fisheye lens element
• Larger prism mirrors and better prism mounting
• Different fiber arrangements
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye with Longer Reflector Prisms
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
AOC 2: Fisheye with Mounting for Longer Reflector Prisms
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Example Fisheye Lens Fiber Map
Hemi 4 Some 125-micron cladding close-packed fibers (many other fiber patterns are possible)
Lens axis rotation 1 2
3 4 5
6 7 8
9 10 11 12
13 14
15 16 17 18
19
20 21 22 23
24 25 26
27 28
29 30 31 32
33 34
35 36 37 38
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74
75 76 77 78 79 80 81 82
83 84 85 86 87 88 89 90 91
92 93 94 95 96
97 98 99 100 101
102 103 104 105
106 107 108 109 110
111 112 113 114 115 116 117 118 119
120 121 122 123 124 125 126 127
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 Fiber #
>120 points plotted Points can be added and positions shifted. Close-pack could be 64% tighter with 80-micron cladding fibers.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Footprints of Beams
11:32:25
f30j (NSS hybrid fisheye)
SURFACE18
BCF28-Sep-11
1.50
MM
X=0.000
Y=0.000
Hemi 4 Some 125-micron cladding close-pack fibers 10:55:52
f30j (NSS hybrid fisheye)
SURFACE15
BCF27-Sep-11
1.67
MM
X=0.000
Y=0.000
Right prism mirror face Top of fisheye lens element
100º 90º 80º
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
S2 Plot
S2 axis lined up to fiber. Points can be added and positions shifted. >120 points plotted.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
S2 Plot
Will move points here.
S2 axis lined up to fiber. Points can be added and positions shifted.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
S2 Plot
S2 axis lined up to fiber. Points can be added and positions shifted. >120 points plotted.
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Angular Separation
0 1 2 3 4 5 6 7 8 9
10
0 20 40 60 80 100 120 140 160 180 200
Series1
S2 axis lined up to fiber. Points can be added and positions shifted. >120 points plotted.
Polar Angle
Diff
eren
ce in
Pol
ar A
ngle
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Ferrule for Fibers
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
15:45:24
f26b Scale: 7.50 BCF 24-Oct-11
3.33 MM
Lens Design Changes
0
20
40
60
80
100
120
0 1 2 3 4
Anl
ge
fiber R (mm)
f25d
Linear Angle
f26b
Current design
Future reduced distortion design (still in progress)
15:42:55
f25d Scale: 7.50 BCF 24-Oct-11
3.33 MM
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Summary for Fisheye Lens Probe
• Long tracking distance (probe less than 9 mm radius) • Maximum polar angle coverage: ~ ±100 degrees (dome)
using mirrors • Rays go to a <3 mm radius common center point near hydro center • Uses glues and index matching gel (sealed inside) • Includes many spare fibers (measurement points) • Point accuracy using aiming can be <1 mm • Point angular separation:
– Up: Polar 0.5, azimuth 2.6 degrees (if using 80-micron cladding fibers)
– Side: 1st–2nd point, polar 2.6 degrees (if using 80-micron cladding fibers)
Vision – Service – Partnership Managed and Operated by National Security Technologies, LLC Nevada National Security Site
6th Annual Photonic Doppler Velocimetry Workshop: Nov 3-4, 2011
Acknowledgments
We have an exceptional team. Some team members are:
Brian Cata, Brian Cox, Edward Daykin, Douglas DeVore, David Esquibel, Daniel Frayer, Cenobio Gallegos, Robert Malone,
Morris Kaufman, and Vince Romero (NSTec)
Special thanks to David Holtkamp (LANL) for support and encouragement.
Thank you to everyone who contributed – Great Job!