MEMS deformable mirrors (DMs) have been developed for applications in adaptive optics, including astronomy [1], [2], [3], vision science [4], microscopy [5], and laser communications [6]. In astronomy, adaptive optics have been used to overcome the image aberrations caused by the Earth's atmosphere. Light from a distant star, which can be considered a point source because it is so far away, travels through the vacuum of space as a plane wave. When the plane wave enters Earth's atmosphere, the wavefront is distorted due to dynamic changes in the index of refraction of the atmosphere caused by winds and temperature fluctuations. These fluctuations in the index of refraction cause changes in the velocity of the wavefront, so that some portions travel faster than others, leading to the distorted wavefront shown in Figure 8.1. These dynamic distortions are what cause stars to appear to twinkle. When the star is imaged in a telescope, it appears as a fuzzy blob rather than a point of light, as shown in Figure 8.1(a). By measuring the wavefront distortions from the star using a wavefront sensor, the conjugate of the wavefront distortion can be applied to a deformable mirror to correct the image, as shown in Figure 8.1(b) and (c). When a star is used as a reference point source for making wavefront corrections, it is called a “guide-star.” If light from a nearby galaxy travels through the same part of the atmosphere, the guide-star can be used to correct the image of the galaxy, as shown in Figure 8.1(b) [7].