Additive Manufacturing of glass opens up new possibilities for the design and integration of optical components. By varying the shape and size of optical elements, optical systems specifically adapted to various applications can be fabricated cost-effectively. The Laser Glass Deposition (LGD) process uses a CO2 laser with a wavelength of 10.6 μm to locally generate temperatures above 2000 °C in fused silica fibers. This enables the Additive Manufacturing and Rapid Prototyping of glass by melting and then layer-by-layer deposition of fibers. However, these high temperatures can result in very high residual stress in the material. The development of a coaxial LGD process aims for a more uniform heating of the glass fiber during the printing process in order to enable a direction-independent process and to reduce the residual stresses within the printed components. In this work, a novel concept for the coaxial LGD process and its successful experimental application is presented. Further, a numerical simulation model is developed to describe the temperature distribution in the glass fiber during the coaxial LGD process. Based on experimental results and on the numerical simulation, the potentials and challenges of the coaxial LGD process are discussed.
There are several techniques for 3D printing glass by sequentially fusing molten tracks. We investigate a process feeding cool glass filament into a CO2 laser to provide local heating. Unlike most crystalline materials, glasses retain significant viscosity when molten. In filament-fed laser heated processing the feed exerts a significant stress on the laser heated region which strongly influences on final track geometry. This introduces challenges but also allows the creation of fully dense glass volumes and free-standing structures. The stress field on the molten region is controlled by using pneumatics and orienting the feed in the moving deposition coordinate system.
There is an increasing demand for highly integrated optical and optoelectronical devices that provide active laser emission, adaptability and low optical losses. A well-established production technology for customized structures with high functionality and geometrical flexibility is additive manufacturing (AM). It enables new constructional degrees of freedom to overcome the limitations of substractive material processing such as milling and drilling. Commercial AM systems for metals and polymers are ubiquitous; whereas glass AM systems almost exclusively exist in scientific environments. Laser glass deposition welding allows the AM of waveguides by fusing coreless
fused silica fibers with a diameter of 400 µm and a 50 µm thick polymer coating onto a fused silica substrate. The deposition process is performed with defocused CO2-laser radiation (10.6 µm). Based on laser deposition welding, the fiber is fed laterally into the processing zone and is melted or fused by the incoming laser beam.
In order to achieve a sufficient coupling of laser radiation into and out of the fibers, a proper cleaving process for the end faces has been established. The cleaving is performed with a CO2-laser based process for optimized and reproducible results. In this contribution, the focus is on the manufacturing of bended waveguides and the feasible bending radii, which can be accomplished during the deposition process. The influence of the bending radius on the guiding efficiency is investigated. Therefore, the light transmission and beam profile of the deposited fibers is measured and compared with an untreated one. Furthermore, the appearance of the cleaved end faces and the internal stress in the glass substrate are characterized. Functional, nearly stress-free curved and straight waveguides for light transmission with high position stability are achieved, which opens a wide range of applications for optical system integration.
The use of additive manufacturing methods in research and industry has led to the possibility of designing more compact, light and low-cost assemblies. In the field of laser development, new opportunities resulting from additive manufacturing have rarely been considered so far. We present a compact, lightweight solid-state amplifier system for low-power applications where the optomechanical components are manufactured completely additive via Fused Filament Fabrication (FFF). The amplifier system is based on a Nd:YVO4-crystal pumped with an external, fiber-coupled diode at a wavelength of 808nm and a maximum output power of 3 W. The seed source is a Nd:YVO4-crystal based solid-state laser with an emission wavelength of 1064 nm. The commercial optical components, such as lenses and crystal, are firmly imprinted via FFF in the optomechanics and thus secured against misalignment. Additionally, sensor technology for temperature measurement is implemented into the devices. The use of FFF, in which the components are printed from polymers, results in a lightweight yet stable construction. We have shown, that optical components can be imprinted without adding mechanical stress. To increase the mechanical and thermal robustness of the system different types of polymers as well as post process treatments are tested and the use of Laser Metal Deposition for this application is investigated. The thermal stability of the printed structures is evaluated to determine the maximum power level of the system without damaging the polymer-optomechanics. Furthermore, output power, optical-to-optical efficiency, beam pointing, and beam shape are measured for several on- and off-switching processes as well as long-term operation.
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