Reflective displays, which harness ambient light, offer energy-efficient alternatives to traditional emissive screens in mobile devices. This review provides an overview of various reflective display technologies and their comparative performance metrics. The review highlights the potential of micro-electromechanical system-based displays, with metrics including 90% reflectance, a contrast ratio of 30, a frequency of 120 Hz, and a resolution of about 350 pixels per inch. Their applicability to mainstream devices such as e-readers, smartphones, and smartwatches continues to be a topic of interest and exploration.

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.

Additive manufacturing of microoptics using two-photon-lithography has been a rapidly advancing field of technology. Striving for ever more sophisticated optical systems prerequisites the access to appropriately fast and accurate wave-optical simulation methods to predict their optical performance. A simulation routine, which has been proven well suited for simulation of a vast range of 3D-printed microoptical systems, is the wave propagation method (WPM). Nevertheless, limitations in applicability remain due to the restriction on scalar electromagnetic fields, which prohibits consideration of polarization and thereby also the calculation of backward reflection at optical interfaces. Capabilities for design and analyses are, therefore, impaired for 3D-printed optical systems using those properties as key features in their design. As a first step to overcome those limitations, we presented new simulation methods based on the WPM in previous publications, extending its applicability toward simulation of vector electric fields, while maintaining short-simulation runtime. We focus on elaborating the practical application and integration of previously presented simulation methods in the design of complex 3D-printed optical systems. With it, we demonstrate the consideration of polarization and backward reflections in simulations far beyond paraxial and thin element approximations.