Curvature wavefront sensors (WFSs), which obtain the wavefront aberrations from two defocused intensity images at each side of the pupil plane, have shown to be highly efficient for astronomical applications. We propose here an alternative defocusing mechanism for curvature sensors, based on an electrowetting-based variable focus liquid lens. Typically, the sampling rates of a WFS for active optics are of the order of 0.01 Hz, and the focus modulation can be done by simply moving the detector back and forth. On the other hand, adaptive optics may require speeds of up to several hundred hertz, and the modulation is then done by using a fast vibrating membrane mirror. We believe variable focus liquid lenses may be able to perform this focus modulation, reducing the overall size of the system and without the need of extra moving parts. We have done a full characterization of the Varioptic Arctic 416 liquid lens, and we have evaluated its potential performance in different curvature configurations.
© 2013 Optical Society of America
Atmospheric and Oceanic Optics
Original Manuscript: July 1, 2013
Revised Manuscript: September 6, 2013
Manuscript Accepted: September 10, 2013
Published: October 15, 2013
Jorge Fuentes-Fernández, Salvador Cuevas, Luis C. Álvarez-Nuñez, and Alan Watson, "Tests and evaluation of a variable focus liquid lens for curvature wavefront sensors in astronomy," Appl. Opt. 52, 7256-7264 (2013)