1. Simulating Atmospheric Strehl
Trex Enterprises
Mentor: Ben Wheeler
Ryan Nora
Summer 2005

2. Some Background on Strehl
Strehl is a mathematical relationship attached to an image.
Strehl is commonly used to measure the performance of an optical system.
Strehl = maximum intensity of the distorted wavefront
maximum intensity of the perfect wavefront

3. The Value of Strehl
A perfect optical setup with no atmospheric distortions would give a Strehl of 1.0 .
Realistically, any optical setup with a Strehl of 0.8 would be considered diffraction limited.
Here are some corrected Strehl values of telescopes across the globe:
UH Int. Astronomy (IR) = .7 um
ESO/France (IR) = 1.25 um and 2.2 um
*This information is from Adaptive Optics for Astronomical Telescopes, J. Hardy, 1998

4. The Project
To simulate atmospheric distortions in a wavefront and calculate its Strehl.
Modeled after the AEOS telescope.
Broken into two simulations to calculate Strehl.

5. Simulation Setup

6. Energy Distribution Background
Intensity Plot
Airy Disk

7. Ideal System
Important Steps in calculating the energy distribution of the ideal system:
Define the amount of light entering the system
Find which frequencies are present
Convert amplitude to intensity

8. Energy Distribution of Ideal System
Diffraction Pattern
Intensity

9. Distorted System
Important Steps in calculating the energy distribution of the distorted system:
Define the amount of light entering the system
Generate distorted wavefront
Find which frequencies are present
Convert amplitude to intensity

10. Simulating the Atmosphere
Zernike coefficients generated from the Kolmogorov turbulence spectrum were used to build the distortions in the wavefront.
* This relationship is from Noll’s paper on Zernikes.

11. Energy Distribution of the Distorted System
Wavefront
Intensity

12. Calculating Strehl
Strehl = maximum intensity of the distorted wavefront
maximum intensity of the perfect wavefront
By creating the aberrations in the simulated wave front similar to what the atmosphere distorts waves in real life, I have calculated an atmospheric Strehl of:
~ 0.03

13. and allow us to collect better data.
Conclusion
The amount of distortion caused by the atmosphere shows us the need to create an Adaptive Optics system to minimize the atmospheric distortions,
and allow us to collect better data.

14. Maui Community College
Many Mahalos to:
Center for Adaptive
Optics
Malika Bell
Lisa Hunter
Liz Espinoza
Trex Enterprises
Ben Wheeler
Dr. Mike Flannigan
Maui Community College
Mark Hoffman
Wallette Pellegrino
This project is supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST