An imaging spectrometer employing tunable hyperchromatic microlenses

We present the design,fabrication and characterization of hydraulically-tunable hyperchromatic lenses for two-dimensional(2D)spectrally-resolved spectral imaging.These hyperchromatic lenses,consisting of a positive diffractive lens and a tunable concave lens,are designed to have a large longitudinal chromatic dispersion and the images of different wavelengths from each other.2D objects of different wavelengths can consequently be imaged using the tunability of the lens system.Two hyperchromatic lens concepts are demonstrated and their spectral characteristics as well as their functionality in spectral imaging applications are shown.

Tip-and Laser-based 3D Nanofabrication in Extended Macroscopic Working Areas

The field of optical lithography is subject to intense research and has gained enormous improvement.However,the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies.This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable:custom design and solutions for specific applications will dominate future development(Fritze in:Panning EM,Liddle JA(eds)Novel patterning technologies.International society for optics and photonics.SPIE,Bellingham,2021.https://doi.org/10.1117/12.2593229).For this reason,new aspects arise for future lithography,which is why enormous effort has been directed to the development of alternative fabrication technologies.Yet,the technologies emerging from this process,which are promising for coping with the current resolution and accuracy challenges,are only demonstrated as a proof-of-concept on a lab scale of several square micrometers.Such scale is not adequate for the requirements of modern lithography;therefore,there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies.Similar challenges arise because of the technical progress in various other fields,realizing new and unique functionalities based on nanoscale effects,e.g.,in nanophotonics,quantum computing,energy harvesting,and life sciences.Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks,which are available at the Technische Universitiit Ilmenau in the form of nanopositioning and nanomeasuring(NPM)machines.With this equipment,the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters.

Development and Implementation of a Rotating Nanoimprint Lithography Tool for Orthogonal Imprinting on Edges of Curved Surfaces

Uniform molding and demolding of structures on highly curved surfaces through conformal contact is a crucial yet often-overlooked aspect of nanoimprint lithography(NIL).This study describes the development of a NIL tool and its integration into a nanopositioning and nanomeasuring machine to achieve high-precision orthogonal molding and demolding for soft ultraviolet-assisted NIL(soft UV-NIL).The process was implemented primarily on the edges of highly curved plano-convex substrates to demonstrate structure uniformity on the edges.High-resolution nanostructures of sub-200-nm lateral dimension and microstructures in the range of tens of microns were imprinted.However,the nanostructures on the edges of the large,curved substrates were difficult to characterize precisely.Therefore,microstructures were used to measure the structure fidelity and were characterized using profilometry,white light interferometry,and confocal laser scanning microscopy.Regardless of the restricted imaging capabilities at high inclinations for high-resolution nanostructures,the scanning electron microscope(SEM)imaging of the structures on top of the lens substrate and at an inclination of 45°was performed.The micro and nanostructures were successfully imprinted on the edges of the plano-convex lens at angles of 45°,60°,and 90°from the center of rotation of the rotating NIL tool.The method enables precise imprinting at high inclinations,thereby presenting a different approach to soft UV-NIL on curved surfaces.

Lau Effect Using LED Array for Lithography

Illumination with LEDs is of increasing interest in imaging and lithography.In particular,compared to lasers,LEDs are temporally and spatially incoherent,so that speckle effects can be avoided by the application of LEDs.Besides,LED arrays are qualified due to their high optical output power.However,LED arrays have not been widely used for investigating optical effects,e.g.,the Lau effect.In this paper,we propose the application of an LED array for realizing the Lau effect by taking into account the influence of the coherence properties of illumination on the Lau effect.Using spatially incoherent illumination with the LED array or a single LED,triangular distributed Lau fringes can be obtained.We apply the obtained Lau fringes in the optical lithography to produce analog structures.Compared to a single LED,the Lau fringes using the LED array have significantly higher intensities.Hence,the exposure time in the lithography process is largely reduced.