Department of Mechanical Engineering, School of Engineering, Shaqra University, P.O. Box 90 Zip Code 11921, Dawadmi, Saudi Arabia.
Nanoscale. 2018 Apr 19;10(15):7095-7107. doi: 10.1039/c8nr00529j.
Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.
光学扩散片为各种需要高斯强度分布的应用提供了一种解决方案，包括成像系统、生物医学光学和航空航天领域。激光烧蚀工艺的进步使得高效光学扩散片的快速生产成为可能。在这里，我们展示了一种使用连续 CO2 激光以低成本高效率制造高质量玻璃光学扩散片的新技术。在玻璃基底的两侧形成了表面浮雕伪随机微结构。温度分布的数值模拟表明，CO2 激光每处理 2 毫秒就可以在玻璃上钻 137 µm 的孔。FFT 模拟用于设计可预测的光学扩散片。通过光学显微镜、拉曼光谱和角度分辨光谱对伪随机微结构进行了表征，以评估它们的化学性质、光学散射、透过率和偏振响应。增加激光曝光和扩散表面的数量可以增强扩散并使入射光均匀化。记录的散斑图案显示出高对比度，在远场观察范围内（250mm）具有无亮点的自由扩散。还开发了一种玻璃表面剥落模型，以防止在制造过程中发生剥落。所展示的方法提供了一种经济有效的方法，可用于以可控和可预测的方式制造光学玻璃扩散片。所生产的光学扩散片可应用于光纤、LED 系统和聚光灯。
