Transcript Adaptive Optics

“Adaptive optics is the most revolutionary technological breakthrough in
astronomy since Galileo pointed his telescope skyward to explore the
heavens 400 years ago.”
- Robert W. Duffner (Air Force Research Lab Historian)
Starlight travels millions
of light years across the
vacuum of space only to
get distorted by our
atmosphere in the last
150 miles before reaching
Earth.
Incoming Distorted Light
Deformable Mirror
Corrected Light
Mirror Commands
Camera Data
Processing Computer
To compensate for the atmosphere, Adaptive Optic Systems use a
Deformable Mirror to correct the incoming light.
Incoming Distorted Light
Deformable Mirror
Corrected Light
Mirror Commands
Camera Data
Processing Computer
A Deformable Mirror is a reflective device that can change its shape quickly, in real-time.
Special cameras, called Wave Front Sensors, measure the atmospheric disturbance and
processing electronics capture the camera data and command the Deformable Mirror to a
figure (shape) that is opposite of the atmospheric distortion. When the light bounces off
the Deformable Mirror it is “straightened”.
This Deformable Mirror is a Micro-Electro-Mechanical (MEM) device.
It has 1024 individual little mirrors that can each piston to a different
position. This device can change its shape 1000’s of times a second.
Mathematical representation of a
32x32 MEM device forming a
focus pattern.
1024 Actuator Mirror courtesy
Boston Micro-Machines
Image courtesy Air Force Research Laboratory
The image on the left is a star viewed without adaptive optics. The image on the
right is the same star but this time using adaptive optics and a deformable mirror
to compensate for the atmosphere.
Results
without
Adaptive
Optics
Results using
Adaptive
Optics
1.5 Meter
Telescope
3.5 Meter
Telescope
Image courtesy Air Force Research Laboratory
SEASAT Satellite
Results using
Adaptive
Optics and
Image
Processing
Hubble Space
Telescope with
Adaptive Optics
Adaptive Optics
Results with Post
Processing
Images courtesy Air Force Research Laboratory
Post-Processing uses images stored on a computer and a series of mathematical
formulas to adjust the contrast, sharpen the images, etc. This technique is
similar to the way in which Photoshop can adjust your digital pictures. Some
algorithms can take minutes to produce an new image.
Laser Guide Star Adaptive Optics:
Many times astronomers want to look
at dim distant stars. These objects
are not bright enough for the Wave
Front Sensor cameras to see. To
compensate for this a laser is sent out
of the telescope and focused several
miles up into the atmosphere.
Dim object that astronomers
want to study.
Artificial star created by a
focused laser.
This creates a bright artificial star
that can be used by the adaptive
optics system. The faint object of
interest can then be viewed
behind the artificial star. The color
of the laser and the color of the
star you wish to study, must be a
different.
Additional Information / History:
The Adaptive Optics Revolution. A History.
Robert Duffner