Membrane mirror with flexible polymer film substrate is a new-concept ultra lightweight mirror for space applications.
Compared with traditional mirrors, membrane mirror has the advantages of lightweight, folding and deployable, low cost
and etc. Due to the surface shape of flexible membrane mirror is easy to deviate from the design surface shape, it will
bring wavefront aberration to the optical system. In order to solve this problem, a method of membrane mirror wavefront
aberration correction based on the liquid crystal spatial light modulator (LCSLM) will be studied in this paper.
The wavefront aberration correction principle of LCSLM is described and the phase modulation property of a LCSLM is
measured and analyzed firstly. Then the membrane mirror wavefront aberration correction system is designed and
established according to the optical properties of a membrane mirror. The LCSLM and a Hartmann-Shack sensor are
used as a wavefront corrector and a wavefront detector, respectively. The detected wavefront aberration is calculated and
converted into voltage value on LCSLM for the mirror wavefront aberration correction by programming in Matlab.
When in experiment, the wavefront aberration of a glass plane mirror with a diameter of 70 mm is measured and
corrected for verifying the feasibility of the experiment system and the correctness of the program. The PV value and
RMS value of distorted wavefront are reduced and near diffraction limited optical performance is achieved. On this basis,
the wavefront aberration of the aperture center Φ25 mm in a membrane mirror with a diameter of 200 mm is corrected
and the errors are analyzed. It provides a means of correcting the wavefront aberration of membrane mirror.