In this paper we demonstrate how Holey Fibre (HF) technology can positively impact the field of materials processing and fabrication, specifically Direct Write (DW). DW is the large scale, patterned deposition of functional materials onto both flat and conformal surfaces. Currently, DW techniques involve thermal post-processing whereby the entire structure is enclosed inside an oven, so limiting the DW technique to small, heat resistant surfaces.
Selectively laser curing the ink would allow the ink to be brought up to the required temperature without heating the surrounding substrate material. In addition the ability to trim components would allow miniature circuits to be written and devices to be tuned by changing the capacitance or resistance. HF technology enables in-situ curing and trimming of direct write components using the same rig and length of fibre. HF's with mode areas in excess of 450μm<sup>2</sup> can be routinely fabricated allowing high power transmission whilst retaining the high beam quality of the radiation source.
We will present results of curing and trimming trials which demonstrate that HF's provide a distinct advantage over standard multimode fibres by allowing both curing and machining to be achieved through a single delivery fibre.
Direct Write (DW) is an emerging group of technologies that allow printing of electronic and other functional components out of vacuum, directly onto structural parts and assemblies. With its ability to deposit a wide range of dissimilar materials, and transfer details directly from CAD/CAM, the process is very flexible, enabling rapid progress from design to fabrication. This paper provides an introduction to direct write, and describes the BAE Systems activities in this field. The paper also describes the use of lasers in direct write, and some provisional results on laser curing are presented.
Fiber delivery of intense laser radiation is important for a broad range of application sectors, from medicine through to industrial laser processing of materials, and offers many practical system benefits relative to free space solutions. In recent years, photonic crystal fiber technology has revolutionized the dynamic field of optical fibers, bringing with them a wide range of novel optical properties that make them ideally suited to power delivery with unparalleled control over the beam properties. The DTI funded project: Photonic Fibers for Industrial beam DELivery (PFIDEL), aims to develop novel fiber geometries for use as a delivery system for high power industrial lasers and to assess their potential in a range of "real" industrial applications. In this paper we review, from an industrial laser user perspective, the advantages of each of the fibers studied under PFIDEL. We present results of application demonstrations and discuss how these fibers can positively impact the field of industrial laser systems and processes, in particular for direct write and micromachining applications.
Diffractive optical systems have been developed to allow high efficiency material processing using excimer lasers. These systems allow beam homogenizing and shaping for surface treatments or parallel focusing for multiple hole drilling and production of microrelief. Beam utilization factors of 80% have been achieved.
This paper investigates the laser ablation of materials at high intensities. It is known that when drilling organic materials at low and moderate fluences (0.1 - 50 J/cm<SUP>2</SUP>) the etch depth per pulse increases exponentially with fluence, essentially following the Beer Law absorption characteristic. For carbon fiber composite the ablation rate reaches a level of about 2 micrometer per pulse for high fluences. However when approaching very high intensities (e.g. greater than 10<SUP>10</SUP> W/cm<SUP>2</SUP>) a sharp increase in ablation rate to greater than 30 micrometer per pulse has been observed and used for drilling experiments. Extensive studies of this regime have subsequently been carried out to characterize it. This has included the effect of different focusing lenses and the effect material thickness. For high quality beams the hole quality is good with no heat affected zone and no significant mechanical damage. This new regime may make the large scale excimer laser drilling or cutting of carbon reinforced fiber an economically feasible application due to the increased drilling and cutting rates. Also this method only requires a simple optical system for high beam utilization factors. These issues will be discussed.
Diffractive optical systems have been developed to allow high efficiency material processing using excimer lasers. These systems allow beam homogenizing and shaping for surface treatment and parallel focusing for multiple hole drilling. Beam utilization factors of 80% have been achieved.