Liquid-crystal microlens with focus swing and low driving voltage

Kang, Shengwu; Zhang, Xinyu; Xie, Changsheng

doi:10.1364/ao.52.000381

Cited by 26 publications

(8 citation statements)

References 12 publications

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“…The LC layer is sandwiched between two PI alignment layers fabricated over Al film grown directly on the surface of the ZnSe wafer, which are separated by several layered glass microspacers with an average diameter of ∼7 μm. The rubbing direction of the PI layer over both the top and bottom mirrors are anti parallel [14], and both parallel to the surface of ZnSe wafer. So, the LC molecules are aligned homogeneously.…”

Section: Modeling and Analysismentioning

confidence: 99%

Electrically tunable infrared filter based on the liquid crystal Fabry–Perot structure for spectral imaging detection

Zhang¹,

Muhammmad

Luo³

et al. 2014

Appl. Opt.

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An electrically tunable infrared (IR) filter based on the liquid crystal (LC) Fabry-Perot (FP) key structure, which works in the wavelength range from 5.5 to 12 μm, is designed and fabricated successfully. Both planar reflective mirrors with a very high reflectivity of ∼95%, which are shaped by depositing a layer of aluminum (Al) film over one side of a double-sided polished zinc selenide wafer, are coupled into a dual-mirror FP cavity. The LC materials are filled into the FP cavity with a thickness of ∼7.5 μm for constructing the LC-FP filter, which is a typical type of sandwich architecture. The top and bottom mirrors of the FP cavity are further coated by an alignment layer with a thickness of ∼100 nm over Al film. The formed alignment layer is rubbed strongly to shape relatively deep V-grooves to anchor LC molecules effectively. Common optical tests show some particular properties; for instance, the existing three transmission peaks in the measured wavelength range, the minimum full width at half-maximum being ∼120 nm, and the maximum adjustment extent of the imaging wavelength being ∼500 nm through applying the voltage driving signal with a root mean square (RMS) value ranging from 0 to ∼19.8 V. The experiment results are consistent with the simulation, according to our model setup. The spectral images obtained in the long-wavelength IR range, through the LC-FP device driven by the voltage signal with a different RMS value, demonstrates the prospect of the realization of smart spectral imaging and further integrating the LC-FP filter with IR focal plane arrays. The developed LC-FP filters show some advantages, such as electrically tunable imaging wavelength, very high structural and photoelectronic response stability, small size and low power consumption, and a very high filling factor of more than 95% compared with common MEMS-FP spectral imaging approaches.

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Section: Modeling and Analysismentioning

confidence: 99%

Electrically tunable infrared filter based on the liquid crystal Fabry–Perot structure for spectral imaging detection

Zhang¹,

Muhammmad

Luo³

et al. 2014

Appl. Opt.

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“…15 So far, a number of LC lenses featuring new optical characteristics were fabricated, e.g., that with focus moveable along and off axis, 16 that with a focal length tuned in a wide range, 17 that with focal length adjusted from the negative to positive state, 18 and that with focus swing. 19 Different types of liquid crystal microlens arrays (LCMLAs) are also developed rapidly. [20][21][22][23][24][25][26] In addition, it is notable that LC devices have already been used to extend the DOF of the optical imaging systems.…”

Section: Introductionmentioning

confidence: 99%

An electrically tunable plenoptic camera using a liquid crystal microlens array

Lei

Tong

Zhang

et al. 2015

Review of Scientific Instruments

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Plenoptic cameras generally employ a microlens array positioned between the main lens and the image sensor to capture the three-dimensional target radiation in the visible range. Because the focal length of common refractive or diffractive microlenses is fixed, the depth of field (DOF) is limited so as to restrict their imaging capability. In this paper, we propose a new plenoptic camera using a liquid crystal microlens array (LCMLA) with electrically tunable focal length. The developed LCMLA is fabricated by traditional photolithography and standard microelectronic techniques, and then, its focusing performance is experimentally presented. The fabricated LCMLA is directly integrated with an image sensor to construct a prototyped LCMLA-based plenoptic camera for acquiring raw radiation of targets. Our experiments demonstrate that the focused region of the LCMLA-based plenoptic camera can be shifted efficiently through electrically tuning the LCMLA used, which is equivalent to the extension of the DOF.

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“…The LC layer is sandwiched between two PI alignment layers which are separated by several layered glass micro-spacers with diameter of $7 lm. The rubbing direction of the PI layer over both top and bottom mirrors are antiparallel [16], and both parallel to the surface of ZnSe wafer. So, the LC molecules are aligned homogenously.…”

Section: Introductionmentioning

confidence: 99%