X-ray ptychography provides the highest resolution non-destructive imaging at synchrotron radiation facilities, and the efficiency of this method is crucial for coping with limited experimental time. Recent advancements in multi-beam ptychography have enabled larger fields of view, but spatial resolution for large 3D samples remains constrained by their thickness, requiring consideration of multiple scattering events. Although this challenge has been addressed using multi-slicing in conventional ptychography, the integration of multi-slicing with multi-beam ptychography has not yet been explored. Here we present the first successful combination of these two methods, enabling high-resolution imaging of nanofeatures at depths comparable to the lateral dimensions that can be addressed by state-of-the-art multi-beam ptychography. Our approach is robust, reproducible across different beamlines, and ready for broader application. It marks a significant advancement in the field, establishing a new foundation for high-resolution 3D imaging of larger, thicker samples.

Hard X-ray ptychography has strongly developed during the last decade, enabling one to visualize structural properties of materials at high spatial resolution. By combining it with multi-slicing or tomographic techniques, optically thick samples can be investigated in 3D. Nevertheless, the depth resolution in multi-slicing is often limited to several micrometers by the ptychographic optical system and a full laminographic or tomographic investigation may be hindered by experimental constraints of limited space or acquisition time. Here, we introduce a stereoscopic imaging system using two inclined nanofocused X-ray beams to illuminate a sample at varying angles at the same time. Similar to human vision, adding these stereoscopic views results in considerably improved in-depth resolution beyond the current limits of pure 2D imaging systems. This is especially promising for experimental applications requiring bulky sample environments.

The future of X-ray ptychography, a coherent diffraction imaging method, promises unprecedented resolution and experimental efficiency while probing features on samples that are increasingly more complicated. This is enabled by sophisticated imaging methods, combining highly optimized hardware, software and procedure.

In this thesis, several aspects of an X-ray ptychography experiment are addressed, emphasizing the enhanced versatility and effectiveness achieved through the use of multiple beams.

Starting with a comprehensive understanding of nanofabrication, the production of focusing X-ray optics is discussed. Specifically, a direct-write lithographic process was developed and its details are described, with particular emphasis on electron-beam lithography at 50 kV acceleration voltage on chemically semi-amplified resist. This process is both versatile and precise, ultimately facilitating the fabrication of Fresnel zone plates (FZPs).

The thesis thus reports on the application of several FZPs in parallel, used to generate multiple X-ray beams to perform ptychography. In particular, novel extensions to the standard ptychographic approach are investigated.

Research on multi-beam X-ray ptychography began with closely spaced FZPs, arranged in a linear array on the same chip, emulating and advancing previous research on the topic and demonstrating the readiness of the self-made hardware for more sophisticated implementations. Most notably, the FZPs wereas close as 48 μm from one another, and up to three beams were used contemporarily, extending the imaged field of view (FOV) by a factor of three.

Next, a novel setup was introduced, promoting the concept of adaptivity within the context of multi-beam X-ray ptychography thanks to FZPs that are stacked and motorized. The possibility of moving the focusing optics in between measurements conferred a status of unprecedented versatility to said setup. The optics did not have to be redesigned for every new iteration of the experiment, sample change, or detecting conditions. It was enough to use the respective motors and adapt the setup to the new measurements. Gold nanocrystal clusters were imaged with a variety of beam spacings, enabling imaging over equally spaced regions on the sample and extending the FOV by a factor of two.

The success of this setup led to its implementation in more complicated measurements, ultimately resulting in the demonstration of simultaneous multi-beam and multi-slice ptychography—these two had never been put together before.

Two-layered samples were imaged, with a layer-to-layer separation ranging from 1400 μm down to 100 μm, with no compromise in resolution as compared to single beam ptychographic measurements.

Finally, the focusing action of FZPs was combined with reflection by curated mirrors to provide an angled perspective on samples in a novel X-ray stereo vision experiment. Here, the depth resolution on a multi-layered sample could be improved from several μm down to 300 nm, again, with no compromise on resolution as compared to single beam ptychography.

For all of these approaches to X-ray ptychography there is one major implication: samples that are larger in all three dimensions can be more readily addressed. In fact, optimized multi-beam X-ray ptychography makes use of more coherent flux from the X-ray source, distributing more photons on the sample and collecting more data across a larger field of view during the same experiment time. Furthermore, thanks to multi-slicing and stereo vision, the depth resolution aspect can be addressed simultaneously.

Framtiden för röntgenptykografi, en koherent diffraktionsavbildningsteknik, ser lovande ut, med rekordupplösning och ökad experimentell effektivitet på studier av prover som blir alltmer komplexa. Detta möjliggörs av sofistikerade avbildningsmetoder som kombinerar optimerad hårdvara, mjukvara och procedurer.

I denna avhandling behandlas flera aspekter av ett framgångsrikt röntgenptykografiexperiment, där mångsidighet och effektivitet uppnås genom implementeringen av flera strålar. 

Utgångspunkten är detaljerad kunskap omnanofabricering, där produktionen av fokuserande röntgenoptik diskuteras. Specifikt utvecklades en direkt-skrivning litografisk process, vars detaljer beskrivs med särskild betoning på elektronstrålitografi vid 50 kV accelerationsspänning på kemiskt semi-amplifierad resist. Denna process är mångsidig och precis, vilket i slutändan möjliggör tillverkningen av Fresnel-zonplattor (FZP). 

Avhandlingen berättar sen om tillämpningen av flera FZP:er parallellt, som används för att generera flera röntgenstrålar för att utföra röntgenptykografi. Särskilt undersöks nya utvidgningar av den standardiserade ptychografiska metoden. 

Forskningen kring multi-stråle röntgenptykografi inleddes med tätt placerade FZP:er, arrangerade i en linjär matris på samma chip, vilket emulerade och avancerade tidigare forskning inom ämnet och visade att den egenproducerade hårdvaran var redo för mer sofistikerade experiment. Mest anmärkningsvärt var att FZP:erna var så nära som 48 μm från varandra, och upp till tre strålar användes samtidigt, vilket utökade det avbildade synfältet (FOV) med en faktor av tre. 

Nästa steg var att introducera en ny uppställning, som främjar konceptet adaptivitet inom ramen för multi-stråle röntgenptykografi tack vare FZP:er som är staplade och motoriserade. Möjligheten att flytta den fokuserande optiken mellan mätningar gav uppställningen en oöverträffad mångsidighet. Optiken behövde inte omdesignas för varje ny iteration av experimentet, provändring eller detektorsinställning. Det räckte med att använda de respektive motorerna och justera avståndet mellan optiken för de nya mätningarna. Nanokristallkluster av guld avbildades med en mängd olika strålavstånd, vilket möjliggjorde avbildning över lika fördelade områden på provet och utökade FOV med en faktor av två. 

Framgången med denna setup ledde till dess implementation i mer komplicerade mätningar, vilket slutligen resulterade i demonstrationen av samtidig multi-stråle och multi-slice ptykografi – dessa två hade aldrig varit andvända tillsammans tidigare. Två-lagers prover avbildades, med ett avstånd mellan lagren som varierade från 1400 μm ner till 100 μm, utan kompromiss i upplösning jämfört med enstråle ptykografiska mätningar. 

Slutligen kombinerades den fokuserande effekten av FZP:er med reflektion från specialdesignade speglar för att ge en vinklad perspektiv på proverna i ett nytt röntgenstereosynexperiment. Här kunde djupupplösningen på ett flerlagersprov förbättras från flera μm ner till 300 nm, återigen utan kompromiss på upplösningen jämfört med enstråle ptykografi.

För alla dessa tillvägagångssätt till röntgenptykografi finns det en viktig implikation: prover som är större i alla tre dimensioner kan mer lätt adresseras. Faktum är att optimerad multi-stråle röntgenptykografi utnyttjar mer koherent flöde från röntgenkällan, vilket distribuerar fler fotoner på provet och samlar in mer data över ett större synfält under samma experimenttid. Dessutom, tack vare multi-slicing och stereosyn, kan djupupplösningsaspekten adresseras samtidigt.

Ptychography has evolved as an important method for nanoscale X-ray imaging with synchrotron radiation. Recently, it has been proposed to work with multiple beams in parallel. The main advantage of so-called multi-beam ptychography is that larger areas can be imaged much faster than with a conventional single beam scan. We introduce adaptive multi-beam ptychography performed with two Fresnel zone plates, placed one behind the other. In contrast to previous demonstrations of multi-beam ptychography, our optical scheme allows for adapting the spatial beam separation to the needs of the sample under investigation, relaxes thickness requirements on zone plates and is straightforward to implement. Moreover, it is simple to switch between single and multi-beam illumination during the same experiment. This opens the possibility of combining large and fast overview scans with detailed imaging of certain regions of interests.

The new imaging endstation of the NanoMAX beamline is being designed to complement the already existing diffraction endstation: measurements with smaller beams at lower photons energies, with higher stability, in vacuum and with sample cooling at the measurement position, optimized for X-ray fluorescence mapping and ptychographic imaging in two and three spatial dimensions. This comes at the cost of reduced flexibility and fewer degrees of freedom. We hereby present the results of the in-air commissioning of the main components for the new endstation and the data quality that has already been achieved.

X-ray ptychography is often implemented for nanoimaging at synchrotron radiation sources and extensions are being developed to make experiments faster. This work is on multi-beam ptychography with Fresnel zone plates that have a small lateral separation, enabling the imaging of an extended field of view without increasing exposure time. Sectional zone inversion is implemented for coding respective probes and up to three Fresnel zone plates are successfully used in parallel. The speed-up achieved, compared to single beam ptychography, is linear with the number of probes. The combination of versatility of the fabrication process for the Fresnel zone plates and performance enhancement by scanning in multi-beam mode makes this an optimal solution for studying samples fast and obtaining enlarged fields of view.

X-ray zone plates made from gold are common optical components used in X-ray imaging experiments. These nanostructures are normally fabricated using a combination of electron-beam lithography and gold electroplating with cyanide gold baths. In this study, we present a gold electroplating process in a miniaturized gold-suplphite bath. The miniaturization is enabled by on-chip reference plating areas with well defined sizes, offering a reliable way to control the height of the structures by carefully choosing the plating time at a given current density in accordance with a calibration curve. Fabricated gold zone plates were successfully used in X-ray imaging experiments with synchrotron radiation. Although gold electroplating of nanostructures is a well-established method, details about the actual process are often missing in the literature. Therefore, we think that our detailed descriptions and explanations will be helpful for other researchers that would like to fabricate similar structures.

Electron-beam lithography (EBL) is a relevant technique to the nanoscience community as it enables the production of precise structures at the nanoscale. When writing features in a thick resist layer, dose insufficiency is typically encountered when resolution approaches the focal spot of the electron beam itself. We present a study of this phenomenon, a theory for its understanding and compensation, and a method for the assignment of the correct area dose for writing small features. Dose insufficiency originates from the proximity effect distributing energy in volumes of resist that are larger than intended. Based on a simple interpretation of the spread, a proximity effect correction (PEC) algorithm was established. Implementing this, we could realize high-quality nanostructures with direct-write 50 kV EBL on AR-P 6200 (CSAR 62) resist. The latter translates to quick and inexpensive exposures that offer good compatibility with further processes.

X-ray ptychography provides the highest resolution non-destructive imaging atsynchrotron radiation facilities, and the efficiency of this method is crucial forcoping with limited experimental time. Recent advancements in multi-beam ptychographyhave enabled larger fields of view, but spatial resolution for large3D samples remains constrained by their thickness, requiring consideration ofmultiple scattering events. Although this challenge has been addressed usingmulti-slicing in conventional ptychography, the integration of multi-slicing withmulti-beam ptychography has not yet been explored. Here we present the firstsuccessful combination of these two methods, enabling high-resolution imagingof nanofeatures at depths comparable to the lateral dimensions that can beadressed by state-of-the-art multi-beam ptychography. Our approach is robust,reproducible across different beamlines, and ready for broader application. Itmarks a significant advancement in the field, establishing a new foundation forhigh-resolution 3D imaging of larger, thicker samples.

Hard X-ray ptychography has strongly developed during the last decade enablingone to visualize structural properties of materials at high spatial resolution. By combining itwith multi-slicing or tomographic techniques also optically thick samples can be investigatedin 3D. Although the depth resolution in multi-slicing is often limited to several micrometersby the ptychographic optical system, a full laminographic or tomographic investigation may behindered by experimental constraints of limited space or acquisition time. Here, we introducea stereoscopic imaging system using two inclined nanofocused X-ray beams to illuminate asample at varying angles at the same time. Similar to human vision, adding these stereoscopicviews results in considerably improved in-depth resolution beyond the current limits of pure 2Dimaging systems. This is especially promising for experimental applications requiring bulkysample environments.