Optimized actuators for ultra-thin mirrors
A method and apparatus for correcting error modes of a deformable mirror, including selecting or targeting one or more target error modes of a deformable mirror; and designing a pattern and/or shape of one or more electrodes, wherein the pattern and/or shape of the electrodes are designed to optimally correct the target error modes when the electrodes are disposed on the deformable mirror via an active material. Also disclosed is a deformable structure, including a composite shell including a plurality of plies each including carbon fibers embedded in a resin; a nanolaminate comprising individual nanolayers attached to a first side of the composite shell; an actuation structure attached to a second side of the composite shell; and a flexible electrode routing layer attached to the actuation structure.
1. A deformable mirror, comprising:
a set of actuation structures attached to a mirror, the actuation structures each comprising:
a first length in a first direction and a second length in a second direction, wherein:
the first length is longer than the second length,
the first directions of the actuation structures are rotated with respect to each other,
the actuation structures intersect in an intersection region and each comprise the intersection region between a first region and a second region;
an active material; and
an electrode on each of the regions of the actuation structures and connected to the active material, the electrodes correcting target error modes when the active material changes shape and deforms the mirror in response to biases applied to the electrodes.
2. The deformable mirror of claim 1 , further comprising:
a common electrode;
the electrodes arranged across the mirror to increase correctability of the mirror, stroke of the mirror, or the stroke and the correctability of the mirror, for a chosen number of the regions and for a specific wavefront error of the mirror; and
the active material changing shape in response to electric fields applied between the electrodes and the common electrode, thereby changing a shape of the mirror to increase the correctability, the stroke, or the stroke and the correctability; wherein:
the correctability is defined as a ratio between a root mean square amplitude of the wavefront error before and after correction by the actuation structures, and
the stroke is defined as the maximum amplitude of the wavefront error that can be corrected without saturating the actuation structures.
3. The deformable mirror of claim 2 , further comprising:
a pattern and a shape of the regions that achieves the desired correctability, the desired stroke, or the desired stroke and the desired correctability, wherein the desired correctability, desired stroke, or the desired stroke and desired correctability are calculated by expressing the target error modes with Zernike polynomials.
4. The deformable mirror of claim 1 , wherein:
a pattern and a shape of the regions are designed to correct the target error modes expressed as a sum of Zernike modes each having an amplitude, and
the target error modes are selected based on the amplitude of the Zernike mode and by selecting the more dominant error modes.
5. The deformable of claim 1 , further comprising a circuit connected to the electrodes, the circuit applying:
equal and opposite voltages to the electrodes on the first regions of each of the actuator structures, and
equal and opposite voltages to the electrodes on the second regions of each of the actuator structures.
6. The deformable mirror of claim 1 , further comprising a plurality of the set of the actuation structures attached to the deformable mirror, wherein the actuation structures in different sets have different lengths and the smaller sets are nested within the larger sets.
7. A method of fabricating a deformable mirror, comprising:
attaching a set of actuation structures to a mirror, the actuation structures each comprising:
a first length in a first direction and a second length in a second direction, wherein:
the first length is longer than the second length,
the first direction of the actuation structures are rotated with respect to each other,
the actuation structures intersect in an intersection region and each comprise the intersection region between a first region and a second region;
an active material; and
an electrode on each of the regions of the actuation structures and connected to the active material, the electrodes correcting target error modes when the active material changes shape and deforms the mirror in response to biases applied to the electrodes.
8. The method of claim 7 , further comprising:
providing a common electrode; and
arranging the electrodes across the mirror to increase a correctability of the mirror, a stroke of the mirror, or the stroke and the correctability for a chosen number of the electrodes and for a specific wavefront error of the mirror; and wherein:
the active material changes in shape in response to electric fields applied between the electrodes and the common electrode, thereby changing a shape of the mirror to increase the correctability, the stroke, or the correctability and the stroke, and
the correctability is defined as a ratio between a root mean square amplitude of the wavefront error before and after correction by the actuation structures, and
the stroke is defined as the maximum amplitude of the wavefront error that can be corrected without saturating the actuation structure.
9. The method of claim 8 , further comprising:
selecting the desired correctability, the desired stroke, or the desired stroke and the desired correctability for the mirror, and
designing a pattern and a shape of the regions that achieves the desired correctability, the desired stroke, or the desired stroke and the desired correctability, wherein the desired correctability, desired stroke, or the desired stroke and desired correctability are calculated by expressing the target error modes with Zernike polynomials.
10. The method of claim 7 , wherein:
the target error modes are expressed as a sum of Zernike modes each having an amplitude,
the target error modes are selected based on the amplitude of the Zernike mode and by selecting the more dominant error modes.
11. The method of claim 7 , wherein a pattern and a shape of the regions are designed by simulating the effect of varying a shape and a pattern of the electrodes on correcting the target error modes.
12. The method of claim 11 , wherein the simulating includes parameterizing the shape of the electrodes.
13. The method of claim 7 , further comprising providing a circuit applying:
equal and opposite voltages to the electrodes on the first regions of each of the actuator structures, and
equal and opposite voltages to the electrodes on the second regions of each of the actuator structures.
14. The method of claim 7 , further comprising attaching a plurality of the set of the actuation structures on the deformable mirror, wherein the actuation structures in different sets have different lengths and the smaller sets are nested within the larger sets.