“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. 

To compensate for the atmosphere, Adaptive Optic Systems use a Deformable Mirror to correct the incoming light.

Deformable Mirror

Incoming Distorted Light

Corrected Light

Camera Data Mirror Commands

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”.

Deformable Mirror

Incoming Distorted Light

Corrected Light

Camera Data Mirror Commands

Processing Computer

Mathematical representation of a 32x32 MEM device forming a focus pattern. 

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.

1024 Actuator Mirror courtesy Boston Micro-Machines 

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. 

Image courtesy Air Force Research Laboratory 

Results without

Adaptive Optics

Results using Adaptive Optics

Results using Adaptive

Optics and Image

Processing

Image courtesy Air Force Research LaboratorySEASAT Satellite 

1.5 MeterTelescope

3.5 MeterTelescope

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.  

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.

Dim object that astronomers want to study. 

Artificial star created by a focused laser. 

Additional Information / History:

The Adaptive Optics Revolution. A History.

Robert Duffner