Defocus measuring the focal length of microlens array by grating prismatic interference

2010 ◽  
Author(s):  
Xianchang Zhu ◽  
Xuedong Cao ◽  
Shibin Wu ◽  
Fan Wu
Keyword(s):  
Focal Length ◽  
Microlens Array

scholarly journals Electrically Tunable-Focusing Liquid Crystal Microlens Array with Simple Electrode

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 431 ◽  
Author(s):  
Li-Lan Tian ◽  
Fan Chu ◽  
Hu Dou ◽  
Lei Li ◽  
Qiong-Hua Wang
Keyword(s):  
Liquid Crystal ◽  
Indium Tin Oxide ◽  
Focal Length ◽  
Microlens Array ◽  
Operating Voltage ◽  
Focusing Effect ◽  
Horizontal Orientation ◽  
Wide Range ◽  
Planar Electrodes ◽  
The Individual

An electrically tunable-focusing liquid crystal (LC) microlens array exhibiting a wide-range tunable focal length is proposed. The lower substrate has strip indium tin oxide (ITO) electrodes, the upper substrate has periodic ITO electrodes with a certain gap coated on the inner surface., and an LC microlens is generated between the two strip electrodes. For each LC microlens, the gap between the top planar electrodes is directly above the center of the microlens. Unlike the conventional LC lens, the individual LC microlens is not coated with ITO electrodes on the central part of its upper and lower substrates, which helps to maintain the LC’s horizontal orientation. In the voltage-off state, the focal length of the microlens array is infinity because of the homogeneous LC alignment. At a given operating voltage, an ideal gradient refractive index distribution is induced over the homogeneous LC layer, which leads to the focusing effect. The simulation result shows that the focal length of the LC microlens could be gradually drawn to 0.381 mm with a change of voltage.

scholarly journals Electrically-Tunable Blue Phase Liquid Crystal Microlens Array Based on a Photoconductive Film

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 65 ◽  
Author(s):  
Bing-Yau Huang ◽  
Shuan-Yu Huang ◽  
Chia-Hsien Chuang ◽  
Chie-Tong Kuo
Keyword(s):  
Refractive Index ◽  
Liquid Crystal ◽  
Electric Field ◽  
Uv Light ◽  
Focal Length ◽  
Incident Light ◽  
Microlens Array ◽  
Gradient Distribution ◽  
Phase Liquid ◽  
Blue Phase

This paper proposes an effective approach to fabricate a blue phase liquid crystal (BPLC) microlens array based on a photoconductive film. Owing to the characteristics of photo-induced conducting polymer polyvinylcarbazole (PVK), in which conductivity depends on the irradiation of UV light, a progressive mask resulting in the variation of conductivity is adopted to produce the gradient distribution of the electric field. The reorientations of liquid crystals according to the gradient distribution of the electric field induce the variation of the refractive index. Thus, the incident light experiences the gradient distribution of the refractive index and results in the focusing phenomenon. The study investigates the dependence of lens performance on UV exposure time, the focal length of the lens, and focusing intensities with various incident polarizations. The BPLC microlens array exhibits advantages such as electrically tunability, polarization independence, and fast response time.

Focal length measurement of microlens-array based on wavefront testing principle of Hartmann-Shack sensor

2013 ◽  
Vol 21 (5) ◽  
pp. 1122-1128
Author(s):  
朱咸昌 ZHU Xian-chang ◽  
伍凡 WU Fan ◽  
曹学东 CAO Xue-dong ◽  
吴时彬 WU Shi-bin
Keyword(s):  
Focal Length ◽  
Microlens Array ◽  
Length Measurement

Fabrication of a focal length variable microlens array based on a nematic liquid crystal

2003 ◽  
Vol 21 (1-3) ◽  
pp. 643-646 ◽  
Author(s):  
Yoonseuk Choi ◽  
Jae-Hong Park ◽  
Jae-Hoon Kim ◽  
Sin-Doo Lee
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Focal Length ◽  
Microlens Array ◽  
Length Variable

Focal length measurement of microlens array for Shack–Hartmann wavefront sensor using interferometer

2013 ◽  
Vol 52 (12) ◽  
pp. 124103 ◽  
Author(s):  
M. Senthil Kumar ◽  
C. S. Narayanamurthy ◽  
A. S. Kiran Kumar
Keyword(s):  
Focal Length ◽  
Microlens Array ◽  
Length Measurement ◽  
Wavefront Sensor

scholarly journals Depth-of-Field-Extended Plenoptic Camera Based on Tunable Multi-Focus Liquid-Crystal Microlens Array

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4142 ◽  
Author(s):  
Mingce Chen ◽  
Wenda He ◽  
Dong Wei ◽  
Chai Hu ◽  
Jiashuo Shi ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Radiation Power ◽  
Focal Length ◽  
Microlens Array ◽  
Oxide Semiconductor ◽  
Depth Of Field ◽  
Digital Refocusing ◽  
Wide Range ◽  
Cmos Sensor ◽  
Plenoptic Camera

Plenoptic cameras have received a wide range of research interest because it can record the 4D plenoptic function or radiance including the radiation power and ray direction. One of its important applications is digital refocusing, which can obtain 2D images focused at different depths. To achieve digital refocusing in a wide range, a large depth of field (DOF) is needed, but there are fundamental optical limitations to this. In this paper, we proposed a plenoptic camera with an extended DOF by integrating a main lens, a tunable multi-focus liquid-crystal microlens array (TMF-LCMLA), and a complementary metal oxide semiconductor (CMOS) sensor together. The TMF-LCMLA was fabricated by traditional photolithography and standard microelectronic techniques, and its optical characteristics including interference patterns, focal lengths, and point spread functions (PSFs) were experimentally analyzed. Experiments demonstrated that the proposed plenoptic camera has a wider range of digital refocusing compared to the plenoptic camera based on a conventional liquid-crystal microlens array (LCMLA) with only one corresponding focal length at a certain voltage, which is equivalent to the extension of DOF. In addition, it also has a 2D/3D switchable function, which is not available with conventional plenoptic cameras.

Study on Micro Fabrication of Mold Insert for Microlens Arrays by Micro Dispensing

2007 ◽  
Vol 364-366 ◽  
pp. 48-52
Author(s):  
Yung Kang Shen ◽  
Yi Lin ◽  
Dong Yea Sheu ◽  
Ming Der Ger ◽  
Yi Han Hu ◽  
...  
Keyword(s):  
Focal Length ◽  
Surface Profile ◽  
Mold Insert ◽  
Microlens Array ◽  
Hot Embossing ◽  
Silver Layer ◽  
Processing Temperature ◽  
Master Mold ◽  
Processing Parameter ◽  
Halogen Light

This work used micro dispensing technology to fabricate the master of microlens array, then uses electroforming technology to replication the Ni mold insert of microlens array and finally used micro hot embossing to replicate the plastic microlens array. This work used the Si10 resin by AutoStrade Company for dispensing material. The resin material was exposed to 80W halogen light. The resin will be hardened and become convex by surface tension effect on exposition. It can be used as the master of microlens array. This work sputtered a silver layer of 150 nm thick on the master for conducting electricity layer. The electroforming technology replicateed on the Ni mold insert from the master of microlens array. Finally, the micro hot embossing technology was used to replicate the molded microlens array. The molding experiment used PMMA and PC optical film. The experiment studied the influence of processing parameters of hot embossing by processing temperature, embossing pressure, embossing time and de-molding temperature. This work used the Taguchi’s Method to search the best processing parameter for molded microlens array. This work used the microscope, surface profiler and SEM to measure the surface profile of master, mold insert and molded microlens array. This work also used AFM to measure the surface roughness of master, mold insert and molded microlens array. In addition, this work measured the optical strength and the focal length to discuss optical characteristics of molded microlens array.

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