secrets of adaptive opticshipacc.ucsc.edu/images/2012bootcamp/cajbc slides... · why adaptive...
TRANSCRIPT
![Page 1: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/1.jpg)
Secrets of Adaptive Optics
Claire Max UC Santa Cruz
Center for Adaptive Optics June 25, 2012
![Page 2: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/2.jpg)
Secrets of Adaptive Optics
Claire Max UC Santa Cruz
Center for Adaptive Optics June 25, 2012
The Planet Neptune
Without adaptive optics
With adaptive optics
![Page 3: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/3.jpg)
Outline
• What is adaptive optics and how does it work?
• Examples of astrophysics enabled by AO
• Computational challenges (present, future)
• AO for imaging the living human retina
• Summary
![Page 4: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/4.jpg)
Introduction to adaptive optics
Even ground-based 8 - 10 meter telescopes have no better spatial resolution than a 20 cm backyard telescope!
• Turbulence in the Earth’s atmosphere is what limits the spatial resolution of ground-based telescopes
• Turbulence is why stars twinkle
• More important for astronomy, turbulence spreads out the light from a star; makes it a blob rather than a point
![Page 5: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/5.jpg)
Why Adaptive Optics?
• AO is a technique for correcting optical distortions to dramatically improve image quality.
• Useful in astronomy, vision science, laser eye surgery, communications, high-powered lasers, …
Lick Observatory, 1 m telescope, Arcturus
Long exposure: blurred image
Short exposure!image
Adaptive Optics image!
![Page 6: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/6.jpg)
Short exposure images, bright star (should be a point of light)
Image is greatly magnified and slowed down
![Page 7: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/7.jpg)
Adaptive optics corrects for atmospheric blurring
Measure details of blurring from “guide star” near the object you want to observe
Calculate on a computer the shape
to apply to a deformable mirror to
correct blurring
Light from both guide star and astronomical
object is reflected from deformable mirror;
distortions are removed
![Page 8: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/8.jpg)
Adaptive optics system runs a “closed-loop control system”
• Measure optical distortions 100’s of times a second with a “wavefront sensor”
• Computer calculates, in a few milliseconds, signals that need to be sent to the deformable mirror to correct these distortions
• Reshape the deformable mirror according to the instruction signals
• Do this over and over again
I will discuss computational challenges later in this talk
![Page 9: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/9.jpg)
Infra-red images of a star showing improvement using adaptive optics
With adaptive optics No adaptive optics
![Page 10: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/10.jpg)
Adaptive optics increases peak intensity of a point source
Credit: Lick Observatory
No AO" With AO"
No AO" With AO"
Intensity"
![Page 11: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/11.jpg)
How a deformable mirror works: zero’th order approximation
BEFORE AFTER
Incoming Wave with Aberration
Deformable Mirror
Corrected Wavefront
![Page 12: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/12.jpg)
![Page 13: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/13.jpg)
Deformable mirrors come in many sizes
30 cm
MEMS 1000 actuators
1 cm
Glass facesheet 1000 actuators
Adaptive Secondary
Mirrors
Xinetics"
U Arizona"
Boston Micro-
Machines"
![Page 14: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/14.jpg)
Adaptive optics needs a bright "star" nearby
Less than 10% of objects in the sky have a bright enough star nearby!
“Same turbulence”
“Different turbulence”
![Page 15: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/15.jpg)
Example: Hubble Deep Field
• Almost every object is a distant galaxy
• Only one star in this image (and it’s dim!)
![Page 16: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/16.jpg)
If there is no nearby star, make your own “star” using a laser
Crucial for extragalactic astrophysics
Happer, MacDonald, Max, Dyson
Implementation!
Facility lasers at Lick & Keck Observatories, Gemini, Subaru,
Palomar, MMT, VLT, ...
Concept!
![Page 17: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/17.jpg)
AO systems at Both Keck Telescopes
Mauna Kea Volcano, Hawaii Island
![Page 18: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/18.jpg)
Dye laser amplifier
Yellow laser beam
Laser at Keck II Telescope atop Mauna Kea, HI
Keck 2 laser was joint project of Keck Observatory & LLNL
Adaptive optics inside
this enclosed
room
Took most of a decade to complete and optimize
![Page 19: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/19.jpg)
Today most major observatories have laser guide star AO
• Allows you to observe almost anywhere in the sky – Not exactly everywhere, because you still need a dim star for
image stabilization
• A major benefit for extragalactic astronomy – Galaxies are distributed randomly on the sky, not just near
bright stars!
• Hence strong interest in installing laser guide star AO on the largest telescopes
• Existing systems at Keck, Gemini N + S, Subaru, VLT observatories
• Planned at LBT, GTC
![Page 20: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/20.jpg)
Outline
• What is adaptive optics and how does it work?
• Examples of astrophysics enabled by AO
• Computational challenges (present, future)
• AO for imaging the living human retina
• Summary
![Page 21: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/21.jpg)
The planet Neptune in infrared light: The benefits of adaptive optics (AO)
Keck Telescope no AO
Hubble Space Telescope NICMOS camera
Keck Telescope with AO
2.4 meter telescope
~2 arc sec
10 meter telescope 10 meter telescope
λ /D• In absence of turbulent distortions, spatial resolution should
scale as (observing wavelength ÷ telescope diameter).
• So with AO, 10-meter Keck telescope should have 4 times better resolution than HST, at the same observing wavelength. ✔"
![Page 22: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/22.jpg)
HR 8799 EXO-planetary system!
• Detected at Gemini, Keck, and MMT Observatories with AO
• 60 Myr old parent star
• 130 light-years away
• 4 planets: 7-10 MJupiter
• ~ circular orbits • ~ face on
• Formed in a disk?
Marois et al., Science, Nov. 13 2008
![Page 23: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/23.jpg)
Hubble Space Telescope images of some nearby galaxy mergers
![Page 24: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/24.jpg)
Galaxy Evolution: Potential role of galaxy mergers and active galactic nuclei
• Active galactic nuclei: galaxies that have actively accreting black holes in their cores
• All galaxies with bulges have black holes; most not active
• Mass of black hole is correlated with bulge properties. Why?
• One explanation: They both grow together during galaxy mergers
Hopkins, Hernquist et al. "
![Page 25: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/25.jpg)
Example: NGC 6240, a nearby merger of two gas-rich galaxies
• Relatively nearby: ~300M light-years
• Double nucleus
• Tidal tails due to merger (“bow-tie”)
AO guide star
• A starburst galaxy (very intense star formation) • Hosts 2 actively accreting black holes
Hubble Space Telescope"
![Page 26: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/26.jpg)
Computer simulation of how merging disk galaxies form bow-tie shapes and tidal tails
Josh Barnes (Univ. Hawaii) : 2 disk galaxies plus their dark-matter halos (red)
![Page 27: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/27.jpg)
Computer simulation of how merging disk galaxies form bow-tie shapes and tidal tails
Josh Barnes (Univ. Hawaii) : 2 disk galaxies plus their dark-matter halos (red)
![Page 28: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/28.jpg)
A closer look at the NGC 6240 galaxy merger, using AO
Conventional image,
Lick Observatory
Hubble Space Telescope, Visible light
Near-infrared image, Keck laser guide star
adaptive optics
Ongoing merger between two massive disk galaxies
X
X
X = position of a supermassive black hole"
![Page 29: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/29.jpg)
Outline
• What is adaptive optics and how does it work?
• Examples of astrophysics enabled by AO
• Computational challenges (present, future)
• AO for imaging the living human retina
• Summary
![Page 30: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/30.jpg)
Computational challenges for AO involve “Real-Time Control”
• Fundamentally different kind of computing than used on super-computers for astrophysical modeling.
• “Real-Time Control” – Sensing and responding to external events almost simultaneous
with their occurrence. – Results of the computation are used to influence a process
while it is taking place.
• Other examples of real-time control systems: – Home: thermostat, toilet tank, automatic toaster – Autopilot for boat or plane, car cruise control – SCADA control for industrial processes (electricity generation
and distribution, factories, water treatment plants, …)
![Page 31: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/31.jpg)
A close-to-home real-time control system: you, grasping an object
Control System Components
• Sensor (eyes)
• Computer (brain)
• Actuators (arm, hand, fingers)
![Page 32: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/32.jpg)
What determines how big a computer is needed for adaptive optics?
• Depends on how ambitious the AO system is, and how large the telescope
• Number of actuators behind the deformable mirror grows like telescope diameter D2 (area of mirror)
• Also need more actuators if you are observing at shorter wavelengths (e.g., visible light)
– Today most AO systems observe in infrared light
• Fundamental timescale: time it takes wind to blow a turbulent element across telescope mirror (a few msec)
![Page 33: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/33.jpg)
Some examples of real-time computer systems used in AO
Observatory / Telescope Diam. Observing wavelength
# mirror actuators
Computer
Lick / 3 meters infrared 60 PC
Keck / 10 meters infrared 249 8 DSP's
LBT / 8 meters infrared 672 336 DSP's
Thirty Meter Telescope (proposed) infrared ~ 6700
thousands of DSP's or FPGAs or GPUs
• Challenge: design and build a real-time computer that can calculate instructions for 5000 – 10,000 mirror actuators in a millisecond!
DSP: digital signal processor FPGA: floating point gate arrays GPU: graphical processing unit"
![Page 34: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/34.jpg)
A few words about SCADA control systems
• SCADA = Supervisory Control and Data Acquisition
• A type of control system
• Widely used in industry, electric utilities, water treatment plants, …
• SCADA system controlling Iran’s gas centrifuges to enrich Uranium was hacked by STUXNET
• SCADA systems are not inherently susceptible to hacking, but at present they have many vulnerabilities. Lack of attention to security.
• Genuine worry for critical infrastructure such as electric grid
![Page 35: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/35.jpg)
Outline
• What is adaptive optics and how does it work?
• Examples of astrophysics enabled by AO
• Computational challenges (present, future)
• AO for imaging the living human retina
• Summary
![Page 36: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/36.jpg)
Why is adaptive optics needed for the human eye?
• Around edges of lens and cornea, imperfections cause distortion
• In bright light, pupil is much smaller than size of lens, so distortions don’t matter much
• But when pupil is large, incoming light passes through the distorted regions
• Results: Poorer night vision (flares, halos around streetlights). Can’t image the retina very clearly (for medical applications)
Edge of lens" Pupil"
![Page 37: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/37.jpg)
Images of a point source for various pupil sizes
1 mm 2 mm 3 mm 4 mm 5 mm 6 mm 7 mm
Perfect Eye
Typical Eye
AO
C. of Austin Roorda
![Page 38: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/38.jpg)
Adaptive optics allows imaging of individual cone photoreceptors (color vision detectors)
Without AO With AO: individual cone photoreceptors
AO + dedicated instruments: 3D structure!
Credit: Austin Roorda, UC Berkeley
![Page 39: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/39.jpg)
Watch individual blood cells flow through capillaries in the eye
• Courtesy of Austin Roorda, UC Berkeley
• 3D sectioning of the retina with confocal microscopy
• Resolve capillaries, individual white blood cells
• Measure velocity of blood flow, …
![Page 40: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/40.jpg)
Main points
• Adaptive optics and laser guide stars have become key instruments at largest (8 – 10m) telescopes
• Number of scientific publications growing very fast
• Real-time computing requirements OK for current systems, a challenge for next generation giant telescopes
• Exciting applications to vision science, and now AO microscopy for biology
Science papers/yr using laser guide stars"
![Page 41: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/41.jpg)
Three lasers over Mauna Kea
![Page 42: Secrets of Adaptive Opticshipacc.ucsc.edu/images/2012BootCamp/CAJBC Slides... · Why Adaptive Optics? • AO is a technique for correcting optical distortions to dramatically improve](https://reader034.vdocuments.mx/reader034/viewer/2022042313/5edc9295ad6a402d66674ab8/html5/thumbnails/42.jpg)
Movie of 3 laser guide stars over Mauna Kea"