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Nematic liquid crystal spatial light modulators (LC-SLMs) have been proposed as wavefront correctors for adaptive optics (a summary of which is described in ref. 1 and references therein). For example, at the last OSA/ESO meeting on adaptive optics in Garching (1995) we described a high-quality LC-SLM which had 69-direct driven pixels which was custom designed for adaptive optics applications2. Additional work has been done with the goal of producing a polarization insensitive LC-SLM which does not suffer the reduced efficiency of a device which only works with a single polarization3. This paper demonstrates successful application of an LC-SLM to wavefront compensation and the first successful application of phase diversity sensing4 to wavefront compensation, to the best of our knowledge.

In the past we have presented work on using nematic liquid crystal spatial light modulators (LC-SLMs) as wavefront correctors for adaptive optics (a summary of which is described in ref. 1 and references therein). For example, at the last OSA/ESO meeting on adaptive optics in Garching (1995) we described a high-quality LC-SLM which had 69-direct driven pixels which was custom designed for adaptive optics applications2. One of the fundamental problems of this device, and of nematic LC-SLMs in general, is that they are inherently polarization sensitive, i.e. they can only phase modulate linearly polarized light. The use of a polarizer, and the associated wastage of light, is unacceptable for many applications, especially astronomy. In this paper we describe an LC-SLM which has been custom designed for adaptive optics and which can phase modulate unpolarized light.