An automated optical alignment method is necessary for the efficient operation of deployable optic-equipped earth observation micro-satellites. Implementation of a linear output feedback controller for the alignment of an active optic is investigated on the Control Test Bed (CTB). The output feedback controller calculates the required positional adjustments of the optic using a multi-variable output measurement. The CTB is a refractive optical system by which the wavefront of an incoming collimated beam is modified by control inputs that adjust the position of a lens. The position of this lens can be translated in the x, y, and z axes (despace and defocus) and rotated about the x and y axes (tip and tilt). In the CTB, a Shack-Hartmann wavefront sensor (SHWFS) measures the output as Zernike coefficients. This setup is intended to emulate the necessary adjustments in a simple deployable optic. We describe the process of developing the output feedback controller that can align the CTB as well as discuss the implications of the scheme to a space-based deployable optic telescope. The aberrations induced by misalignment of the active lens were characterized experimentally by disturbing the system along each degree of freedom about the optically aligned point. The experimental results derive a state observer that can sufficiently estimate the misalignment of the lens from a set of relevant Zernike coefficients. Iterative correction of the estimated misalignment in a closed-loop allowed consistent convergence of the CTB to a nearly flat wavefront.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
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.