Limits...
Design and fabrication of a large-stroke deformable mirror using a gear-shape ionic-conductive polymer metal composite.

Wei HC, Su GD - Sensors (Basel) (2012)

Bottom Line: Finally, a gear shaped IPMC actuator was designed and tested.Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts.The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Section 4, Taipei 10617, Taiwan. d96941017@ntu.edu.tw

ABSTRACT
Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM) provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC) is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young's modulus and Poisson's ratio. We divided an ion exchange polymer, also known as Nafion(®), into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

No MeSH data available.


The surface profile of IPMC using an atomic force microscope (AFM). (a) the non-improved surface (Rrms = 1.29 μm); (b) the improved surface (Rrms = 0.036 μm).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472876&req=5

f11-sensors-12-11100: The surface profile of IPMC using an atomic force microscope (AFM). (a) the non-improved surface (Rrms = 1.29 μm); (b) the improved surface (Rrms = 0.036 μm).

Mentions: Figure 9(a) is the picture of the fabricated IPMC deformable mirror. The central displacement was approximately 0.6 mm and the corresponding optical power was 17 diopters (m−1) under two volts of applied voltage. Figure 9(b) shows the deformation profile which was simulated by ANSYS®. The experimental result of a reflected laser spot by flat and curved IPMC DM is shown in Figure 10. The laser spot was focused on a point approximately 6 cm from the DM. The corresponding optical power was approximately 17 diopters. Because of the diffused metal particles caused by surface roughening in step (b) in Figure 6 of the fabrication process, the laser spot was somewhat scattered. Comparing with a flat IPMC mirror, the actuated IPMC mirror focused 50% more energy in the 2 mm diameter. In other words, the collimated light was focused successfully. Figure 10 illustrates the intensity profile of the laser spot reflected by the non-actuated IPMC (non-focused) and the actuated IPMC (focused). To overcome this phenomenon, we spun a layer of polydimethylsiloxane (PDMS) as a buffer layer to make the surface smoother. Meanwhile, a layer of 500 nm metal reflector was deposited by an e-beam evaporator. The comparison of improved surface roughness is shown in Figure 11 by using an atomic force microscope (AFM; OBJ-204C, ITRI, Hsinchu, Taiwan). Figure 11(a) shows the non-improved surface with scars caused by sandpaper. Figure 11(b) shows the improved surface. The root-mean-square roughness was improved from 1.29 μm to 0.036 μm. According to previous work by Bar-Cohen et al., [14], encapsulation techniques were also investigated to successfully preserve the moisture content when the voltage level is below two volts. Meanwhile, Nemat-Nasser [15] presented results using ethylene glycol as solvent. They found out that IPMC with ethylene glycol has greater solvent uptake. It can be subjected to higher voltages without electrolysis. Compared to water, it can be actuated in open air for long time periods.


Design and fabrication of a large-stroke deformable mirror using a gear-shape ionic-conductive polymer metal composite.

Wei HC, Su GD - Sensors (Basel) (2012)

The surface profile of IPMC using an atomic force microscope (AFM). (a) the non-improved surface (Rrms = 1.29 μm); (b) the improved surface (Rrms = 0.036 μm).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472876&req=5

f11-sensors-12-11100: The surface profile of IPMC using an atomic force microscope (AFM). (a) the non-improved surface (Rrms = 1.29 μm); (b) the improved surface (Rrms = 0.036 μm).
Mentions: Figure 9(a) is the picture of the fabricated IPMC deformable mirror. The central displacement was approximately 0.6 mm and the corresponding optical power was 17 diopters (m−1) under two volts of applied voltage. Figure 9(b) shows the deformation profile which was simulated by ANSYS®. The experimental result of a reflected laser spot by flat and curved IPMC DM is shown in Figure 10. The laser spot was focused on a point approximately 6 cm from the DM. The corresponding optical power was approximately 17 diopters. Because of the diffused metal particles caused by surface roughening in step (b) in Figure 6 of the fabrication process, the laser spot was somewhat scattered. Comparing with a flat IPMC mirror, the actuated IPMC mirror focused 50% more energy in the 2 mm diameter. In other words, the collimated light was focused successfully. Figure 10 illustrates the intensity profile of the laser spot reflected by the non-actuated IPMC (non-focused) and the actuated IPMC (focused). To overcome this phenomenon, we spun a layer of polydimethylsiloxane (PDMS) as a buffer layer to make the surface smoother. Meanwhile, a layer of 500 nm metal reflector was deposited by an e-beam evaporator. The comparison of improved surface roughness is shown in Figure 11 by using an atomic force microscope (AFM; OBJ-204C, ITRI, Hsinchu, Taiwan). Figure 11(a) shows the non-improved surface with scars caused by sandpaper. Figure 11(b) shows the improved surface. The root-mean-square roughness was improved from 1.29 μm to 0.036 μm. According to previous work by Bar-Cohen et al., [14], encapsulation techniques were also investigated to successfully preserve the moisture content when the voltage level is below two volts. Meanwhile, Nemat-Nasser [15] presented results using ethylene glycol as solvent. They found out that IPMC with ethylene glycol has greater solvent uptake. It can be subjected to higher voltages without electrolysis. Compared to water, it can be actuated in open air for long time periods.

Bottom Line: Finally, a gear shaped IPMC actuator was designed and tested.Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts.The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Section 4, Taipei 10617, Taiwan. d96941017@ntu.edu.tw

ABSTRACT
Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM) provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC) is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young's modulus and Poisson's ratio. We divided an ion exchange polymer, also known as Nafion(®), into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

No MeSH data available.