Spectroscopy has emerged as an essential technology, particularly in decentralized utilization within point-of-care devices. These applications demand compact, cost-effective designs with reduced complexity compared with traditional laboratory equipment. Achieving compactness often involves minimizing the number of components, necessitating that each remaining component fulfills multiple functions to optimize performance. However, this approach can lead to significant aberrations due to constructive compromises. Nevertheless, the known phase errors enable correction, often achieved directly through diffractive elements. Diffractive compensation of aberrations is commonly conducted through interference lithography, exploiting holographic techniques to produce gratings without explicit knowledge of the interference structure. Alternatively, mechanical manufacturing techniques offer the possibility of producing blazed gratings with greater efficiency. However, diffractive correction using mechanically fabricated gratings requires a precise understanding of individual groove trajectories, presenting an ongoing challenge. We employed ultraprecision (UP) mechanical manufacturing techniques to create aberration-corrected diffraction gratings for spectroscopic applications. To enable the machining of freeform trajectories, facilitating versatile fabrication of both planar and concave imaging blazed gratings, a modified five-axis UP machinery is employed. To correct the known wavefront errors of the exemplary use cases, a nonlinear phase function was applied and a numerical method was developed to derive trajectories from the phase errors and translate them into machine code. The use cases are a blazed imaging planar Littrow grating and concave Rowland gratings, showcasing corrected astigmatic wavefront deviation. The theoretical and experimental results are compared and discussed.
Gallium Phosphide (GaP) is a semiconductor with advantageous optical properties for near- and middle infrared optical systems. However, optical applications of GaP are limited by its current low machinability. To cut brittle semiconductors such as GaP and generate optical quality surfaces, it is necessary to induce a High-Pressure Phase Transformation (HPPT) so that a phase is formed that behaves ductile when machined. Along the cutting process this can be achieved by applying a negative rake angle. Otherwise, cracks will appear on the machined surface, worsening its optical capabilities. A HPPT of GaP happens at an atomic scale when a zincblende structure changes into a β-tin one. The β-tin structure behaves ductile and is metastable. Hence, the metastable β-tin phase cannot be observed during the cutting process. Therefore, atomistic simulation, such as Classic Molecular Dynamics Simulation (CMDS), is required to study the machinability under HPPT. In this work, CMDS were used to analyze GaP cutting mechanisms. A diamond tool was modelled with a cutting edge radius rβ = 10 nm, rake angle γ = -20 º, and clearance angle α = 10 º. The cut was performed with a depth of cut ap = 12 nm along the [100]-direction in a zincblende GaP workpiece. Stacking faults were found on the shear zone, {111}-planes, by two different post processes approaches. HPPT was found in the deformation zone only. A stagnation zone was found in front of the cutting edge proceeding a crack nucleation.
Many industrial devices for X-Ray fluorescence analysis have a need for more optical brilliance. The heart of these devices, the X-ray tube, uses a focused electronic beam to produce the X-ray. The quality of electronic spot is one of the most important criteria for brilliance. The development of high brilliance X-ray tubes requires extensive systemic consideration, which often occurs in cycles. The draft and design process should be optimized in a result-oriented manner. Multicriteria optimization is used to pursue consistently a systemic approach of derivative-free and gradientbased methods. The interaction of the electric particles with the field, considering geometric, physical, and material parameters, influences the definition of the objective function. The objective function includes the geometry of a spot, being an ellipse, and the physical value of a multivariate Gaussian distribution. The second one says how many electrons there are on the spot. The set point approximates an actual value with the aid of a quadratic difference in the multicriteria optimization. The investigation of specific electron quantities per area happens with a double integral for every concentric ellipse selection of the spot. The analysis of electron trajectories helps to design the special shape of the Wehnelt cylinder, which is supported by multicriteria optimization. Results show that simultaneous systemic development reduces the number of design cycles and enables influence on the objective functions already in the preliminary design phase.
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