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Nature-Inspired Quasicrystal SRG Using Fibonacci Sequences in Photo-Reconfiguration on Azo Polymer Films
摘要： In this study, we present the fabrication route of quasicrystal surface relief grating (SRG) of azopolymer. Based on photo-reconfigurable azobenzene property, various morphologies of grating patterns were inscribed on azopolymer thin-films by two-beam coupling light interference lithography (LIL) process. Multiplexing the LIL with different rotation sequence on azopolymers resulted in unusual surface structures including quasicrystal-like SRGs with Fibonacci sequences in rotational LIL. We investigated the effect of rotation sequence on the grating patterns by atomic force microscope, revealing that rotation sequence is a critical parameter determining surface structures of azopolymer films.
关键词： holographic optical elements,diffraction gratings,optical fabrication
更新于2025-09-23 15:21:21
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Materials Science and Technology of Optical Fabrication || Material Removal Rate
摘要： This chapter covers the last of the four major characteristics of optical fabrication, material removal rate (see Figure 1.6). As discussed in Chapter 1, the macroscopic material removal rate is governed by the Preston equation (Equation (1.3)), where removal rate largely scales linearly with applied pressure and relative velocity, and all the process and material parameters are lumped into the Preston coefficient kp. The Preston equation can be applied to both grinding (which is discussed in Section 5.1) and polishing (Section 5.2). The parameters that govern material removal rate and resulting surface roughness are intimately connected. Hence, the principles of the ensemble Hertzian multi-gap (EHMG) and island distribution gap (IDG) models, as discussed in Chapter 4, can be largely applied when discussing polishing material removal rate.
关键词： optical fabrication,IDG model,material removal rate,Preston equation,grinding,polishing,EHMG model
更新于2025-09-10 09:29:36
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Materials Science and Technology of Optical Fabrication || Increasing Yield: Scratch Forensics and Fractography
摘要： If a workpiece falls and breaks catastrophically, the cause of failure is obvious. But a workpiece may fracture catastrophically (or noncatastrophically) for many reasons far more difficult to diagnose and hence, prevent or mitigate. For such purposes, the field of fractography – the science of means and methods of characterizing a fractured component by examining its fracture pattern and surface – can be very useful. The theory and practice of fractography are well described by Frechette [1], Varner and Frechette [2], Quinn [3], Freiman and Mecholsky [4], and Bradt and Tressler [5]. This chapter first provides a fractography introduction, describing the major features observed on the fracture surfaces and what information they provide about failure. Next, the fractography is extended to diagnosing yield loss due to scratching a workpiece, using a technique called scratch forensics and to insights on the time-dependent fracture failure caused by slow crack growth. Finally, some relevant case studies of the fractured workpieces during optical fabrication analyzed by fractography and scratch forensics are presented.
关键词： fracture analysis,fractography,optical fabrication,slow crack growth,scratch forensics
更新于2025-09-09 09:28:46
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Materials Science and Technology of Optical Fabrication || Novel Process and Characterization Techniques
摘要： There are many conventional optical-fabrication process and characterization techniques, and they are well documented in the literature [1, 2]. These include the following: ? Interferometry techniques and test plating to measure surface ?gure, wedge, and parallelism ? Needle pro?lometry, white-light interferometry, and atomic force microscopy (AFM) to measure surface roughness ? Optical, confocal, and dark-?eld microscopy and visual inspection to measure surface quality ? Baume density ?oats, pH sensors, and particle-size analyzers to characterize polishing slurries ? Hardness testers to characterize lap materials, particularly pitch In this chapter, some novel techniques (and perhaps obscure techniques) that provide additional insight into the optical-fabrication process are described. Chapters 2–5 focused on the phenomena that govern the basic properties of a workpiece during and after optical fabrication, namely surface ?gure, surface quality, surface roughness, and material removal rate. The novel process and characterization techniques explored in this chapter are described for an optical-fabrication engineer or an optician who might wish to use them.
关键词： optical-fabrication,AFM,interferometry,characterization techniques,polishing slurries
更新于2025-09-09 09:28:46
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Materials Science and Technology of Optical Fabrication || Surface Figure
摘要： As described in Section 1.2, one of the major characteristics of the final optic is the surface figure, or long-range surface shape of the workpiece. Achieving the desired surface figure is a primary objective in fabricating an optic, because surface figure influences the wavefront modification of the incoming light, both in transmission and reflection. At the most basic level, the final surface figure of the workpiece is simply determined by its initial surface shape and the amount of material removed from each point on the workpiece surface, discounting residual stress changes. Hence, to quantitatively (i.e. deterministically) determine surface figure evolution in a given finishing process, one must understand all the phenomena that contribute to the material removal rate at each point and as a function of time. A useful approach to describe and organize these phenomena is to expand the traditional material removal rate Preston equation (Equation (1.3)). Preston’s equation may be described in a more general form as follows: [1]
关键词： material removal rate,Preston equation,surface figure,optical fabrication,polishing
更新于2025-09-09 09:28:46