Abstract:In this work we describe the use of laser direct-write for the rapid prototyping of frequency selective surfaces. Frequency selective surfaces are generally described by a periodic array of conducting or dielectric features (i.e. crosses, loops, grids, etc.) that when properly designed can pass or reject specific frequency bands of incoming electromagnetic radiation. While simple frequency selective surfaces are relatively straight forward to design and fabricate, operational demands, particularly military, ha… Show more
“…All the microfluidics discussed in this paper were laser micro-machined. The laser micro-machining system used for this purpose was previously built for a variety of different rapid prototyping applications [ 39 – 41 ], and is shown schematically in Fig. 1 Fig.…”
Several new bio-photonic techniques aim to measure flow in the human vasculature non-destructively. Some of these tools, such as laser speckle imaging or Doppler optical coherence tomography, are now reaching the clinical stage. Therefore appropriate calibration and validation techniques dedicated to these particular measurements are therefore of paramount importance. In this paper we introduce a fast prototyping technique based on laser micromachining for the fabrication of dynamic flow phantoms. Micro-channels smaller than 20 µm in width can be formed in a variety of materials such as epoxies, plastics, and household tape. Vasculature geometries can be easily and quickly modified to accommodate a particular experimental scenario.
“…All the microfluidics discussed in this paper were laser micro-machined. The laser micro-machining system used for this purpose was previously built for a variety of different rapid prototyping applications [ 39 – 41 ], and is shown schematically in Fig. 1 Fig.…”
Several new bio-photonic techniques aim to measure flow in the human vasculature non-destructively. Some of these tools, such as laser speckle imaging or Doppler optical coherence tomography, are now reaching the clinical stage. Therefore appropriate calibration and validation techniques dedicated to these particular measurements are therefore of paramount importance. In this paper we introduce a fast prototyping technique based on laser micromachining for the fabrication of dynamic flow phantoms. Micro-channels smaller than 20 µm in width can be formed in a variety of materials such as epoxies, plastics, and household tape. Vasculature geometries can be easily and quickly modified to accommodate a particular experimental scenario.
“…Laser fabrication of MMAs including laser surface treatment [19,20], laser etching [21,22], laser 'thick film' printing [22], and laser graphitisation [23] was recently attempted. Laser surface treatments and etching technologies have been used to successfully fabricate conformal MMA structures.…”
Microwave absorbion for radar stealth technology is facing challenges for effectiveness in the low frequency region. Here we report a new laser-based method to produce an ultra-wideband metamaterial based microwave absorber with a high sheet resistance uniformity and negative magnetic permeability leading to the highest relative bandwidth and lowest thickness in the L to S band reported so far. Control of electrical sheet resistance uniformity has been achieved to less than 5% deviation for 400 Ω/sq and 6% deviation for 120 Ω/sq, leading to a microwave absorption coefficient between 97.2%-97.7% within 1.56 GHz-18.3GHz bandwidth for incident angles of 0-40, and there is no need for applying energy or an electrical power source during operation. Porous N- and S- doped turbostratic graphene 2D patterns with imbedded magnetic nanoparticles are produced on polyethylene terephthalate simultaneously during laser direct writing. The proposed low frequency, wide band, wide incident angle and high electromagnetic absorption microwave absorber would have the potential for aviation, EMI suppression and 5G applications.
“…4 These techniques are known as laser micromachining and laser patterning, respectively. Both require the ability to translate the substrate being processed under the laser beam using motion controlled stages, scanning the laser beam over the substrate surface, or a combination of translation/scanning motion.…”
The opportunities presented by the use of metamaterials have been the subject of extensive discussions. However, a large fraction of the work available to date has been limited to simulations and proof-of-principle demonstrations. One reason for the limited success inserting these structures into functioning systems and real-world applications is the high level of complexity involved in their fabrication. Most approaches to the realization of metamaterial structures utilize traditional lithographic processing techniques to pattern the required geometries and then rely on separate steps to assemble the final design. Obviously, composite structures with arbitrary and/or 3-D geometries present a challenge for their implementation with these approaches. Non-lithographic processes are ideally suited for the fabrication of arbitrary periodic and aperiodic structures needed to implement many of the metamaterial designs being proposed. Furthermore, non-lithographic techniques are true enablers for the development of conformal or 3-D metamaterial designs. This article will show examples of metamaterial structures developed at the Naval Research Laboratory using non-lithographic processes. These processes have been applied successfully to the fabrication of complex 2-D and 3-D structures comprising different types of materials.
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