Papers by Keyword: Digital Micromirror Device DMD

Abstract: In rapid prototyping (RP) technologies, curing of UV-curable photopolymers is mainly achieved by the application of laser scanning with limited fabrication speed. The dynamic masking approach can improve the fabrication speed; however, current researches and available systems cure photopolymers with visible light rather than UV light. In this research, we have attempted to develop a UV dynamic masking RP system by implementing digital micro-mirror device (DMD) from digital light processing (DLP) technology and TFT liquid crystal display (LCD) panel. A DLP projector was disassembled and the main components were then recombined to form a dynamic mask generator. Thus, this study has shown the feasibility of obtaining a UV dynamic masking RP system that may be integrated for a UV-curable material processing.

Abstract: A high-accuracy full field 3-D surface profilometer using digital structured fringe projection is presented in the article. In the proposed method, a depth-focus response curve can be established by performing a confocal scanning along the optical axis of the measurement system when a digital fringe is controlled and projected by a digital micromirror device (DMD). To avoid specular light diffusive problems, the developed method projects spatially encoded digital fringe patterns with modulated light intensity onto a shinny lens surface, in order to achieve full field and high accuracy measurement. Some of spherical microlenses have been measured to attest the feasibility of the developed approach. The depth measurement resolution can reach up to 0.1μm and the averaged measurement error was verified to be a submicro scale.

Abstract: As demand for complex precision parts increase, the existing fabrication methods such as MEMS, and LIGA technology have technical limitations with regard to high precision, high aspect ratio, and high complexity. A microstereolithography technology based on DMDTM(Digital Micromirror Device) can meet these demands. DMD enables a system to handle dynamic patterns. In this technology, the same standard format of the conventional rapid prototyping system, the STL file, is used, and 3D parts are fabricated by stacking layers that are sliced as 2D section from STL file. Whereas in conventional methods, the resin surface is cured by scanning laser beam spot according to the section shape, but in this research, we used an integral process which enabled the resin surface to be cured by one irradiation. In this paper, we dealt with the dynamic pattern generation and DMD operation to fabricate microstructures. Firstly, the microstereolithography apparatus and process were discussed. Secondly, the DMD operation according to mirror tilting, and optimal mounters for DMD and reflecting mirror according to light path were described. And thirdly, complex 3D microstructures were demonstrated.

Abstract: A new full-field 3-D micro surface profilometer using digital micromirror device (DMD)-based fringe projection strategy and confocal principle is presented in the article. In viewing the fact that conventional laser confocal measurement method not only easily encounters undesired irregular scattering problems, but also lack scanning efficiency due to its single-point type measurement, the newly developed automatic surface profilometer deploys a DMD chip to project spatially encoded digital fringe patterns with dynamic light intensity, onto the object to obtain excellent measurement performance. A novel digital fringe pattern design with adaptive sinusoidal intensity modulation was developed for active fringe projection, to obtain optimized depth resolution with a micrometer lateral resolution in confocal measurement. Some of semiconductor components have been measured to attest the feasibility of the developed approach. The depth measurement resolution can reach better than 0.1μm and the maximal measured error was verified to be less than less than 0.5 % of the measured step size.

Abstract: The development of a three-dimensional surface profilometer using digital fringe projection technology and phase-shifting principle is presented. Accurate and high-speed three-dimensional profile measurement plays a key role in determining the success of process automation and productivity. By integrating a digital micromirror device (DMD) with the developed system, exclusive advantages in projecting flexible and accurate structured-light patterns onto the object surface to be measured can be obtained. Furthermore, the developed system consists of a specially designed micro-projecting optical unit for generating flexibly optimal structured-light to accommodate requirements in terms of measurement range and resolution. Its wide angle image detection design also improves measurement resolution for detecting deformed fringe patterns. This resolves the problem in capturing effective deformed fringe patterns for phase shifting, especially when a coaxial optical layout of a stereomicroscope is employed. Experimental results verified that the maximum error was within a reasonable range of the measured depth. The developed system and the method can provide a useful and effective tool for 3D full field surface measurement ranging from µm up to cm scale.