Scanning mirror systems and methods of manufacture
A scanning micromirror system includes a base having an axis passing therethrough, a plurality of support flexures coupled to the base, and a platform coupled to the base by the plurality of support flexures. The platform has a first side and a second side opposing the first side and is operable to oscillate about the axis. The scanning micromirror system also includes a stress relief layer positioned on the first side of the platform and a reflector positioned on the first side of the platform. The stress relief layer is positioned between the reflector and the platform.
1 . A scanning micromirror system comprising:
a base having an axis passing therethrough;
a plurality of support flexures coupled to the base;
a platform coupled to the base by the plurality of support flexures, wherein the platform has a first side and a second side opposing the first side and is operable to oscillate about the axis;
a stress relief layer positioned on the first side of the platform, wherein the stress relief layer provides a first stress distribution on the first side of the platform;
a conducting coil positioned on the second side of the platform, wherein the conducting coil provides a second stress distribution on the second side of the platform, and wherein the first stress distribution and the second stress distribution are opposite; and
a reflector positioned on the first side of the platform, wherein the stress relief layer is positioned between the reflector and the platform.
2 . The scanning micromirror system of claim 1 , wherein the stress relief layer comprises the same material as the conducting coil.
3 . The scanning micromirror system of claim 1 , wherein the stress relief layer has a first volume and the conducting coil has a second volume, wherein the first volume is equal to the second volume.
4 . The scanning micromirror system of claim 1 , wherein the conducting coil is arranged to apply magnetic forces to the platform about the axis.
5 . The scanning micromirror system of claim 1 , wherein the conducting coil is embedded into the second side of the platform.
6 . The scanning micromirror system of claim 1 , wherein the conducting coil comprises a first metal and a second metal.
7 . The scanning micromirror system of claim 1 , further comprising a plurality of conductive traces on the plurality of support flexures for providing electrical communication with the conducting coil, and wherein the plurality of conductive traces are arranged on the plurality of support flexures in a configuration to apply opposite stresses on different sides of the plurality of support flexures.
8 . The scanning micromirror system of claim 1 , further comprising a first magnetic field source arranged to apply a first magnetic field to the platform, wherein the first magnetic field source is arranged to provide the first magnetic field oriented orthogonal to the axis.
9 . The scanning micromirror system of claim 1 , further comprising one or more piezoelectric actuators arranged to apply forces to oscillate the platform about the axis or to sense oscillation or position of the platform about the axis.
10 . The scanning micromirror system of claim 1 , further comprising a hermetic packaging enclosing the scanning micromirror system for maintaining a lower pressure at the scanning micromirror system inside the hermetic packaging than outside the hermetic packaging.
11 . The scanning micromirror system of claim 1 , further comprising a passivation layer.
12 . The scanning micromirror system of claim 1 , further comprising a second scanning micromirror system in optical communication with the scanning micromirror system, wherein the second scanning micromirror system comprises:
a second base having a second axis passing therethrough;
a plurality of second support flexures coupled to the second base;
a first frame coupled to the second base by the plurality of second support flexures, wherein the first frame is operable to oscillate about the second axis;
a second platform coupled to the first frame, wherein the second platform has a first side and a second side opposing the first side, wherein the second platform is operable to oscillate about the second axis together with the first frame; and
a second reflector positioned on the second platform.
13 . The scanning micromirror system of claim 12 , wherein the second scanning micromirror system further comprises a strain sensor incorporated in the first frame.
14 . The scanning micromirror system of claim 12 , wherein the scanning micromirror system has a first natural resonant frequency of 1 kHz to 10 MHz and wherein the second scanning micromirror system has a second natural resonant frequency of 15 Hz to about 2 kHz.
15 . The scanning micromirror system of claim 12 , wherein the second scanning micromirror system further comprises a second frame coupled between the first frame and the second platform, wherein the second frame is coupled to the first frame by a plurality of third support flexures and wherein the second frame is operable to oscillate about the second axis together with the first frame and the second platform.
16 . The scanning micromirror system of claim 15 , wherein the second scanning micromirror system further comprises a plurality of piezoelectric actuators incorporated in the second frame, wherein the plurality of piezoelectric actuators are arranged to alter a position of the second platform about a third axis orthogonal to the second axis or to alter a curvature of the second platform.
17 . A method of projecting an image, the method comprising:
providing a scanning micromirror system, wherein the scanning micromirror system comprising:
a base having an axis passing therethrough;
a plurality of support flexures coupled to the base;
a platform coupled to the base by the plurality of support flexures, wherein the platform has a first side and a second side opposing the first side and is operable to oscillate about the axis;
a stress relief layer positioned on the first side of the platform, wherein the stress relief layer provides a first stress distribution on the first side of the platform; and
a reflector positioned on the first side of the platform, wherein the stress relief layer is positioned between the reflector and the platform;
a conducting coil positioned on the second side of the platform, wherein the conducting coil is arranged to apply magnetic forces to the platform about the axis, wherein the conducting coil provides a second stress distribution on the second side of the platform, and wherein the first stress distribution and the second stress distribution are opposite; and
a magnetic field source arranged to apply a magnetic field to the platform;
inducing an oscillation of the scanning micromirror system at a frequency; and
illuminating the reflector with a light source to generate output reflected light.
18 . The method of claim 17 , further comprising directing the output reflected light from the scanning micromirror system to an eyepiece.
19 . The method of claim 17 , further comprising controlling oscillation of the scanning micromirror system and output color and/or intensity of light from the light source.