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Maskless lithography based on digital micromirror device (DMD) and double sided microlens and spatial filter array
摘要： A new type of maskless lithography system based on digital mirror device (DMD) is proposed, constructed, and experimentally demonstrated. It includes a pin-hole array sandwiched by two microlens arrays on each side, known as double-sided microlens/spatial-filter array (D-MSFA), and aligned with a DMD. Ultraviolet (UV) light reflected by DMD is first collected by the first microlens array, filtered through the pin-hole array, and then re-focused by the second microlens array into a UV spot array. Along with an obliquely scanning method, this D-MSFA/DMD-based maskless lithography system can perform not only 2D but also 3D UV patterning. Experimental testing successfully generates complicated patterns with a minimum line-width of 3.36 μm. Direct 3D patterning and 3D microfabrication are also experimentally demonstrated on a photoresist layer. Excellent profile accuracy and surface structure qualities are observed with great potentials for future 2D and 3D microfabrication in a maskless manner.
关键词： Microlens array,Maskless lithography,Digital mirror device (DMD),3D microfabrication
更新于2025-09-23 15:22:29
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Laser based method for dynamic calibration of thermocouples
摘要： In dynamic temperature measurement, thermocouple sensors are widely used in harsh environments, and their dynamic characteristics directly affect the accuracy of dynamic temperature measurement. When the dynamic characteristics do not meet the requirements of dynamic test, dynamic errors will occur. In order to obtain the dynamic characteristics, it is necessary to calibrate the thermocouple dynamically. In this paper, a dynamic calibration system for the thermocouple was built. In the system, a high power laser was used to generate pulse temperature excitation. In order to realize the uniform heating, the laser beam homogenization system based on microlens array was studied and added to the dynamic calibration system. The homogenization system was designed and simulated, and the uniformity of the laser spot was measured after homogenization. A K-type butt-welded thermocouple was dynamically calibrated by using the dynamic calibration system. The dynamic mathematical model of the thermocouple was obtained by the system identification method, and the dynamic characteristics of the thermocouple were analyzed.
关键词： pulse excitation,laser,dynamic calibration,microlens array,thermocouple
更新于2025-09-23 15:21:01
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Fabrication of Random Microlens Array for Laser Beam Homogenization with High Efficiency
摘要： The miniaturized and integrated microlens array (MLA) can effectively achieve the beam homogenization, compactness and miniaturization of laser systems. When the high-coherence laser beam is homogenized by means of using the MLA, interference fringes will occur in the homogenized light spot due to the periodicity of the MLA, which seriously affects the uniformity of the homogenized light spot. To solve this problem, a novel random microlens array (rMLA) structure was proposed for the purpose of achieving beam homogenization. The coherence in the homogenization process is suppressed by means of breaking the periodicity of the MLA. The homogenized light spot with a high energy utilization is then obtained accordingly. In the fabrication process, a clever method of combining chemical etching with lithography technology is performed to fabricate a honeycomb rMLA and a rectangular rMLA. The experimental results show that the energy utilization rate of the two types of the rMLAs is about 90%, and the uniformity of the homogenized light spots generated by the honeycomb rMLA and the rectangular rMLA are more than 80% and 85%, respectively. Meanwhile, fully cost-effective fabrication is possible to be realized.
关键词： random microlens array,beam homogenization,laser,chemical etching
更新于2025-09-23 15:19:57
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Thermally Superstable Cellulosic-Nanorod-Reinforced Transparent Substrates Featuring Microscale Surface Patterns
摘要： The recent rapid expansion of thin-film, bendable, and wearable consumer (opto)electronics demands flexible and transparent substrates other than glass. Plastics are the traditional choice, but they require amelioration because of their thermal instability. Here, we report the successful conversion of a soft and thermally vulnerable polymer into a highly thermally stable transparent nanocomposite material. This is achieved by the meticulous choice of a polymer with a glass-transition temperature below 0 °C that gives stable mechanics above room temperature, reinforcing the polymer with a load-bearing hierarchical network of the incredibly strong and stable natural material: cellulose nanorods. Owing to the Pickering emulsification process, the nanocomposites inherit the self-assembled structural hierarchy from the cellulose nanorod-encapsulated resin droplets. The ameliorated nanocomposites have highly desirable high-temperature endurance (～150?180 °C) in terms of the thermomechanical, thermodimensional, and thermo-optical performance. Any photonic nano- or microstructures can be directly molded on the surface of the nanocomposites in high precision for better light management in photonic and optoelectronic applications. The highlight of this work is the demonstration of a highly thermally stable microlens array on the ameliorated transparent nanocomposite.
关键词： thermal stability,polymer nanocomposites,flexible electronics,Pickering emulsion,microlens array,nanocellulose
更新于2025-09-19 17:15:36
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Split-face comparison of the picosecond 1064-nm Nd:YAG laser using a microlens array and the quasi-long-pulsed 1064-nm Nd:YAG laser for treatment of photoaging facial wrinkles and pores in Asians
摘要： Skin photoaging manifests deeper wrinkles and larger pore size. Various lasers have been tried for rejuvenation of photoaging skin, and the quasi-long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is one promising treatment option. New types of laser device are emerging, including devices operating with picosecond pulse duration combined with a microlens array, which are regarded as a new breakthrough for skin rejuvenation. We aimed to evaluate the clinical effectiveness and safety of the picosecond 1064-nm Nd:YAG laser using a microlens array compared with the quasi-long-pulsed 1064-nm Nd:YAG laser in a split-face design. We designed a split-faced, prospective study and enrolled 25 subjects with photoaging facial wrinkles and enlarged pores. Each facial area was randomly assigned to undergo treatment with either the picosecond 1064-nm Nd:YAG laser (Pico-arm) or the quasi-long-pulsed 1064-nm Nd:YAG laser (Quasi-arm). We performed five laser sessions at 2-week intervals, and final results were assessed after 20 weeks after the initial laser session. We used a five-point global assessment scale, wrinkle and pore index derived from 3D camera analysis. We enrolled a total of 25 subjects (24 females and 1 male) with Fitzpatrick skin types III to IV and a mean age of 63.8 ± 5.7 years. After treatment, 54.2% of subjects in the Pico-arm reported at least moderate improvement in visible pores compared with 41.7% of the Quasi-arm (P = 0.001). A total of 12.5% of subjects in the Pico-arm showed moderate improvement in wrinkles versus 4.2% of the Quasi-arm (P = 0.125). There was a 41.3% reduction in the pore index in the Pico-arm compared to a 3.9% increase in the Quasi-arm (P = 0.048). There was a 16.4% reduction in the wrinkle index in the Pico-arm compared with a 0.5% reduction in the Quasi-arm (P = 0.01). Pain assessment score was higher in the Pico-arm than the Quasi-arm (3.65 ± 1.70 vs 1.28 ± 1.28, P = 0.001). No serious adverse events occurred during the study. Our findings suggest that the picosecond 1064-nm Nd:YAG laser with a microlens array is as effective as the quasi-long-pulsed 1064-nm Nd:YAG laser for treatment of photoaging wrinkles and pores.
关键词： Nd:YAG laser,Photoaging,Microlens array,Wrinkle,Picosecond,Pore
更新于2025-09-16 10:30:52
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Comment on “Improving Light Outcoupling Efficiency for OLEDs with Microlens Array Fabricated on Transparent Substrate”
摘要： The recently published research article, titled “Improving Light Outcoupling Efficiency for OLEDs with Microlens Array Fabricated on Transparent Substrate,” provides a significant design rule for the high extraction efficiency of OLED devices. According to the simulation results, the authors proposed that a well-organized microlens-embedding structure may increase 80% light output efficiency. For an experimental demonstration, about 30% luminance enhancement was induced by a microlens-arrayed substrate. The optical lens design was applied and revealed a noticeable improvement of OLED performances. The authors demonstrated the improved OLED performances by using geometric designs of microlens arrays, which are formed on a glass substrate. The microlens arrays were formed by photoresist material. The photoresist film showed high transmittance above 90% for longer wavelengths (λ>500 nm); however, the photoresist microlens arrays have no electrical advantages for carrier transportation. Meanwhile, we also consider an electrical aspect for further significant enhancement for photoelectric devices, including LEDs and solar cells. A distinctive feature between LEDs and solar cells is a way to utilize energy conversion. LEDs convert the electric energy to light emission and solar cells generate electric power from the incident photon energy. This basic and important understanding may provide mutual applications of photoelectric devices. Previously, we have investigated an indium-tin-oxide (ITO) transparent conducting layer to focus the incident light into the light-reactive semiconducting material. The nanoscale ITO nanodome arrays efficiently focus the incoming light resulting in the enhanced solar cell performances, based on the enlarged current value. This was caused by the optical design to manipulate the light penetration through the Si material. Additionally, the electrical aspect also contributed to increase in current value due to excellent electrical conductivity of the ITO layer, providing an efficient route to collect photogenerated carriers, effectively. This optically and electrically balanced design may be applied in the microlens-arrayed OLED devices. Instead of using the electrically nonconductive material, electrically conductive materials, such as ITO, can be considered for the light-modulating structure. This design would spontaneously provide the electrical advantages and maintain the optical benefit of light manipulation of the patterned structure. To realize these optical and electrical features, one may think of the patterned ITO arrays, which sit on the ITO anode layer. The carriers from organic (light-active) layers can easily reach the ITO anode and the emitted light can efficiently propagate through the patterned ITO arrays. Figure 1 is one of the possible schemes of the functional ITO patterns for efficient OLED. Double anode layers are proposed, where the film ITO is a conventional anode figure and the patterned ITO-array structure is for the functional light extraction. Besides the light management from the patterned ITO-array structure, the electrical conductivity would be enhanced according to double ITO layers.
关键词： OLED,transparent substrate,microlens array,ITO,light outcoupling efficiency,photoelectric devices
更新于2025-09-16 10:30:52
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Self-Assembled Asymmetric Microlenses for Four-Dimensional Visual Imaging
摘要： Visual imaging that can extract three-dimensional (3D) space or polarization information on the target is essential in broad sciences and technologies. The simultaneous acquisition of them usually demands expensive equipment and sophisticated operations. Therefore, it is of great significance to exploit convenient approaches for four-dimensional (3D and polarization) visual imaging. Here, we present an efficient solution based on self-assembled asymmetric liquid crystal microlenses, with freely manipulated phase profiles and symmetry-breaking properties. Accordingly, characteristics of multi-focal functionality and polarization selectivity are exhibited, along with the underlying mechanisms. Moreover, with a specific sample featured by radially increased unit sizes and azimuthally varied domain orientations, the discriminability of four-dimensional information is extracted in a single snapshot, via referring to the coordinates of the clearest images. Demultiplexing of depth/polarization information is also demonstrated. This work will unlock a variety of revolutionary apparatuses and lighten extensive applications.
关键词： polarization detection,liquid crystals,visual imaging,microlens array,self-assembly
更新于2025-09-11 14:15:04
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An optimization method of dynamic patterns based on aspheric microlens array
摘要： An optimization method is proposed to improve the image quality of dynamic patterns in this paper. In order to obtain parallel emergent beam of high quality, aspheric microlens array is used in the optical system. Besides, an analytical model of the substrate and a single aspheric lens of MLA is presented based on the principle of ray tracing which is used in optical design for virtually tracing rays through an optical system. Moreover, how do the parameters influence the image quality is analyzed and the relationship between the conic constant and the divergence angle of emergent beam is derived. Preliminary optimization results with a second order aspheric lens are compared with the simulation results obtained by ZEMAX. The ray tracing method in this article helps improve the image quality of dynamic patterns and has the potential to be used in designing aspheric surface because it offers a way to improve the parallel rays and optimize the parameters of the optical system.
关键词： Aspheric,Ray tracing,Optimization,Microlens array
更新于2025-09-11 14:15:04