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Nicholas Cheng Yang Tham

Bio: Nicholas Cheng Yang Tham is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Surface micromachining & Interference lithography. The author has an hindex of 2, co-authored 5 publications receiving 178 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors introduce laser-based additive manufacturing methods and review the types of lasers widely used in 3D printing machines, and discuss the future prospects of laser technologies for additive manufacturing.
Abstract: In recent years, additive manufacturing, also known as three-dimensional (3D) printing, has emerged as an environmentally friendly green manufacturing technology which brings great benefits, such as energy saving, less material consumption, and efficient production. These advantages are attributed to the successive material deposition at designated target areas by delivering the energy on it. In this regard, lasers are the most effective energy source in additive manufacturing since the laser beam can transfer a large amount of energy into micro-scale focal region instantaneously to solidify or cure materials in air, therefore enabling high-precision and high-throughput manufacturing for a wide range of materials. In this paper, we introduce laser-based additive manufacturing methods and review the types of lasers widely used in 3D printing machines. Important laser parameters relevant to additive manufacturing will be analyzed and general guidelines for selecting suitable lasers for additive manufacturing will be provided. Discussion on future prospects of laser technologies for additive manufacturing will be finally covered.

285 citations

Journal ArticleDOI
TL;DR: This work proposes the concept of "ultrafast volume holography" for the fabrication of stretchable photonic structures such as tunable VPGs directly in unmodified PDMS, and translates insights in heat regulation via fs repetition rate control into volumetric patterning, forming periodic refractive index modulation in PDMS without post-processing.
Abstract: Stretchability and flexibility are two key requirements for manipulating the propagation of light in compact and high-performance lab-on-a-chip systems. These requirements are best met by embedding stretchable and flexible tuning elements such as volume phase gratings (VPGs) in polydimethylsiloxane (PDMS), making them attractive alternatives to conventional rigid optical elements. However, fabrication of these PDMS VPGs is a challenge, requiring extensive modifications to PDMS or complex multi-step processes that require long processing times. In this context, we propose the concept of “ultrafast volume holography” for the fabrication of stretchable photonic structures such as tunable VPGs directly in unmodified PDMS. Our concept translates insights in heat regulation via fs repetition rate control into volumetric patterning, forming periodic refractive index modulation of 1.95 × 10−4 in the PDMS without post-processing. VPGs formed are further demonstrated as active beam steering units and tunable spectroscopic optical elements.

5 citations

Journal ArticleDOI
TL;DR: The figure 15 in page 315 should be modified as below: as mentioned in this paper, and the figure 16 in page 317 is modified as follows: [15]... ]..
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2 citations

Proceedings ArticleDOI
13 Jun 2017
TL;DR: In this paper, a configurable multi-beam femtosecond laser interference is proposed to directly pattern nanoscale periodic features within optically transparent solid materials by means of configurable multiuser laser interference.
Abstract: A method to directly pattern nanoscale periodic features within optically transparent solid materials by means of a configurable multi-beam femtosecond laser interference is proposed. While femtosecond micromachining of optically transparent solid materials has been explored in great detail in the recent past, research in direct interference patterning on such materials has not been well established. Therefore, different design considerations such as complete void formation and flexibility of the patterned substrate are investigated as part of this study. The relationship between intensity distributions and actual void formation in optically transparent materials is also investigated to establish critical parameters for pattern formation. It is envisaged that this proposed method and data obtained may enable to explore the untapped domains of developing substrates for solid-state 3D microbattery applications.

Cited by
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Journal ArticleDOI
TL;DR: A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out in this paper, where the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed.
Abstract: Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

4,159 citations

Journal ArticleDOI
06 Apr 2016
TL;DR: Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs.
Abstract: Propulsion system development requires new, more affordable manufacturing techniques and technologies in a constrained budget environment, while future in-space applications will require in-space manufacturing and assembly of parts and systems. Marshall is advancing cuttingedge commercial capabilities in additive and digital manufacturing and applying them to aerospace challenges. The Center is developing the standards by which new manufacturing processes and parts will be tested and qualified. Rapidly evolving digital tools, such as additive manufacturing, are the leading edge of a revolution in the design and manufacture of space systems that enables rapid prototyping and reduces production times. Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs. Marshall is helping establish the standards and qualifications “from art to part” for the use of these advanced techniques and the parts produced using them in aerospace or elsewhere in the U.S. industrial base.

481 citations

Journal ArticleDOI
TL;DR: This review explores open-cellular structural design for porous metal implant applications, in relation to the mechanical properties, biocompatibility, and biodegradability, of metal implants with an enhanced biomorphic environment.

320 citations

Journal ArticleDOI
TL;DR: In this article, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes, followed by discussion on the potentials of OFS in manufacturing.
Abstract: Environmental monitoring has become essential in order to deal with environmental resources efficiently and safely in the realm of green technology. Environmental monitoring sensors are required for detection of environmental changes in industrial facilities under harsh conditions, (e.g. underground or subsea pipelines) in both the temporal and spatial domains. The utilization of optical fiber sensors is a promising scheme for environmental monitoring of this kind, owing to advantages including resistance to electromagnetic interference, durability under extreme temperatures and pressures, high transmission rate, light weight, small size, and flexibility. In this paper, the optical fiber sensors employed in environmental monitoring are summarized for understanding of their sensing principles and fabrication processes. Numerous specific applications in petroleum engineering, civil engineering, and agricultural engineering are explored, followed by discussion on the potentials of OFS in manufacturing.

236 citations

Journal ArticleDOI
TL;DR: Current research on the statistical and experimental design techniques for different applications or output responses such as enhancing mechanical properties, build time, part quality, etc are reviewed.

155 citations