Alignment and focus control of a telescope using image sharpening

Peter A. Jones

doi:10.1117/12.48807

1 December 1991 Alignment and focus control of a telescope using image sharpening

Peter A. Jones

Proceedings Volume 1542, Active and Adaptive Optical Systems; (1991) https://doi.org/10.1117/12.48807
Event: San Diego, '91, 1991, San Diego, CA, United States

Abstract

Two alternative methods have traditionally been used to maintain telescope alignment and focus. The direct method measures rigid body changes (decentration, tilt and despace) using internal sensors and predicts the resulting performance degradation. The indirect method measures the performance degradation with a wavefront sensor and predicts the rigid body changes. An alternative indirect method uses an image sharpening merit function value derived from the image irradiance data . The image sharpening function has the property that it achieves its maximum value when the image has no residual aberrations. An aberrated image can be improved by introducing aberration corrections using an active mirror until the merit function value is optimized. Therefore, by forming a closed loop between the image detector and the active optical element, a telescope can be realigned and refocused to optimum performance without the use of a separate wavefront sensor or internal alignment/focus sensors. A comparison of the direct and indirect methods and recent experimental results of the image sharpening method are presented.

Citation Download Citation

Peter A. Jones "Alignment and focus control of a telescope using image sharpening", Proc. SPIE 1542, Active and Adaptive Optical Systems, (1 December 1991); https://doi.org/10.1117/12.48807

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available