At-focus scanning ptychography for high resolution imaging with a wide field of view.

From manufacturing to medicine, there is a demand for phase-resolved, high resolution imaging of large samples. Here we present at-focus scanning ptychography (AFSP), a novel ptychographic metrology station designed for high resolution imaging over a large field of view. AFSP builds on scanning ptychography, but samples remain stationary during the imaging process, allowing for in-situ imaging. We demonstrate a resolution of 44.19µm, present images of spherical and freeform optics with a FOV of over 4cm, and validate the fidelity of the AFSP system by comparing it to established commercial instruments. AFSP's comparable performance underscores its credibility as a valuable addition to quantitative phase imaging technologies.

Single-pulse, reference-free, spatiotemporal characterization of ultrafast laser pulse beams via broadband ptychography.

Ultrafast laser pulse beams are four-dimensional, space-time phenomena that can exhibit complicated, coupled spatial and temporal profiles. Tailoring the spatiotemporal profile of an ultrafast pulse beam is necessary to optimize the focused intensity and to engineer exotic spatiotemporally shaped pulse beams. Here we demonstrate a single-pulse, reference-free spatiotemporal characterization technique based on two colocated synchronized measurements: (1) broadband single-shot ptychography and (2) single-shot frequency resolved optical gating. We apply the technique to measure the nonlinear propagation of an ultrafast pulse beam through a fused silica window. Our spatiotemporal characterization method represents a major contribution to the growing field of spatiotemporally engineered ultrafast laser pulse beams.

Spatiospectral characterization of ultrafast pulse-beams by multiplexed broadband ptychography.

Ultrafast pulse-beam characterization is critical for diverse scientific and industrial applications from micromachining to generating the highest intensity laser pulses. The four-dimensional structure of a pulse-beam, E~(x,y,z,ω), can be fully characterized by coupling spatiospectral metrology with spectral phase measurement. When temporal pulse dynamics are not of primary interest, spatiospectral characterization of a pulse-beam provides crucial information even without spectral phase. Here we demonstrate spatiospectral characterization of pulse-beams via multiplexed broadband ptychography. The complex spatial profiles of multiple spectral components, E~(x,y,ω), from modelocked Ti:sapphire and from extreme ultra-violet pulse-beams are reconstructed with minimum intervening optics and no refocusing. Critically, our technique does not require spectral filters, interferometers, or reference pulses.

Multi-mode root preserving ptychographic phase retrieval algorithm for dispersion scan.

We present a phase retrieval algorithm for dispersion scan (d-scan), inspired by ptychography, which is capable of characterizing multiple mutually-incoherent ultrafast pulses (or modes) in a pulse train simultaneously from a single d-scan trace. In addition, a form of Newton's method is employed as a solution to the square root problem commonly encountered in second harmonic pulse measurement techniques. Simulated and experimental phase retrievals of both single-mode and multi-mode d-scan traces are shown to demonstrate the accuracy and robustness of the root preserving ptychographic algorithm (RPPA).

Comparative nasal airflow with loratadine-pseudoephedrine and fluticasone nasal spray for allergic rhinitis.

BACKGROUND: Although it is known that oral antihistamine-pseudoephedrine combination tablets have a faster onset than intranasal corticosteroid sprays in the treatment of allergic rhinitis after the first dose, the magnitude of change has not been measured in a comparative manner. Furthermore, the sensation of sprayed liquid in the nose may lead patients to mistakenly believe that intranasal steroid sprays work instantly. OBJECTIVE: To evaluate, numerically, nasal airflow changes provided by a single dose of loratadine-pseudoephedrine tablet (LP) and fluticasone propionate nasal spray (FP) in participants experiencing allergic rhinitis symptoms, including nasal congestion. METHODS: This single-center, double-blinded, placebo-controlled, crossover study evaluated objective nasal airflow changes in patients with a documented sensitivity to ragweed pollen. Participants were randomized to receive 1 of 4 treatment sequences, and their peak nasal inspiratory flow (PNIF) was measured in a span of 4 hours after pollen exposure in an environmental exposure unit. RESULTS: Average change in PNIF was 31% with LP in the course of the study, significantly greater than with placebo and FP (12% and 15%, respectively; P < .001). Nevertheless, FP did not produce a significant change compared with its placebo. At hour one post-dose, LP had a clinically significant 31% increase in PNIF, whereas FP only yielded an 8.6% increase (P < .001). Measurable nasal airflow improvements are associated with the opening of nasal passages, allowing congested patients to breathe more freely. CONCLUSION: A single dose of LP quickly and significantly (P < .001) improved nasal airflow after ragweed pollen challenge in an environmental exposure unit. Comparatively, FP did not display this same benefit. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03443843.

Nondestructive, high-resolution, chemically specific 3D nanostructure characterization using phase-sensitive EUV imaging reflectometry.

Next-generation nano- and quantum devices have increasingly complex 3D structure. As the dimensions of these devices shrink to the nanoscale, their performance is often governed by interface quality or precise chemical or dopant composition. Here, we present the first phase-sensitive extreme ultraviolet imaging reflectometer. It combines the excellent phase stability of coherent high-harmonic sources, the unique chemical sensitivity of extreme ultraviolet reflectometry, and state-of-the-art ptychography imaging algorithms. This tabletop microscope can nondestructively probe surface topography, layer thicknesses, and interface quality, as well as dopant concentrations and profiles. High-fidelity imaging was achieved by implementing variable-angle ptychographic imaging, by using total variation regularization to mitigate noise and artifacts in the reconstructed image, and by using a high-brightness, high-harmonic source with excellent intensity and wavefront stability. We validate our measurements through multiscale, multimodal imaging to show that this technique has unique advantages compared with other techniques based on electron and scanning probe microscopies.

Three-dimensional single-shot ptychography.

Here we introduce three-dimensional single-shot ptychography (3DSSP). 3DSSP leverages an additional constraint unique to the single-shot geometry to deconvolve multiple 2D planes of a 3D object. Numeric simulations and analytic calculations demonstrate that 3DSSP reconstructs multiple planes in an extended 3D object with a minimum separation consistent with the depth of field for a conventional microscope. We experimentally demonstrate 3DSSP by reconstructing orthogonal hair strands axially separated by 5 mm. 3DSSP provides a pathway towards volumetric imaging of dynamically evolving systems on ultrafast timescales.

Two-dimensional random access multiphoton spatial frequency modulated imaging.

Spatial frequency modulated imaging (SPIFI) enables the use of an extended excitation source for linear and nonlinear imaging with single element detection. To date, SPIFI has only been used with fixed excitation source geometries. Here, we explore the potential for the SPIFI method when a spatial light modulator (SLM) is used to program the excitation source, opening the door to a more versatile, random access imaging environment. In addition, an in-line, quantitative pulse compensation and measurement scheme is demonstrated using a new technique, spectral phase and amplitude retrieval and compensation (SPARC). This enables full characterization of the light exposure conditions at the focal plane of the random access imaging system, an important metric for optimizing, and reporting imaging conditions within specimens.

Clinical symptoms and biomarkers of Bermuda grass-induced allergic rhinitis using the nasal allergen challenge model.

BACKGROUND: Bermuda grass is a prevalent allergen that flourishes in tropical climates. Its exposure is traditionally believed to be low in Ontario due to the colder environment. However, high sensitization rates have been observed in Kingston, Ontario. OBJECTIVE: We sought to investigate whether its allergens can provoke allergic rhinitis (AR) symptoms in sensitized participants from south-eastern Ontario and determine if nasal allergen challenge (NAC) model is appropriate to study Bermuda grass-induced AR. METHODS: Twenty-one participants sensitized to Bermuda grass and 12 nonallergic participants completed a titrated NAC with increasing allergen concentrations at a screening visit. Total nasal symptom score (TNSS) and peak nasal inspiratory flow were collected before allergen exposure and 10 minutes after delivery of each concentration. Twelve participants with a Bermuda grass allergy who met the qualifying criteria (TNSS ≥ 8 and peak nasal inspiratory flow fall ≥ 50%) and 11 nonallergic controls returned for single-dose NAC visit. RESULTS: At titrated NAC, 19 of 21 sensitized participants met the criteria of positive allergic response when challenged. During single-dose NAC, participants with allergy had significantly greater TNSS between 15 minutes and 3 hours after NAC than controls. Likewise, allergic participants had a significantly increased number of nasal lavage eosinophils at both 1 and 6 hours after NAC. Bermuda grass-specific immunoglobulin E was significantly increased in Bermuda grass allergic participants at NAC than screening visit. CONCLUSION: Although Bermuda grass is a non-native allergen in Ontario, it can induce AR symptoms in sensitized participants, and the NAC model is appropriate to study Bermuda grass-induced AR.

Spectral phase and amplitude retrieval and compensation technique for measurement of pulses.

In this Letter, an in-line, compact, and efficient quantitative pulse compensation and measurement scheme is demonstrated. This simple system can be readily deployed in multiphoton imaging systems and advanced manufacturing where multiphoton processes are exploited.

Clinical standardization of two controlled allergen challenge facilities: The Environmental Exposure Unit and the Biogenics Research Chamber.

BACKGROUND: Controlled allergen challenge facilities (CACF), in disparate geographic regions with dissimilar engineering and base populations, have historically functioned as single, independent sites in clinical allergy trials. We aimed to demonstrate "between-unit reproducibility" to allow controlled challenge trials of participants using 2 CACFs. OBJECTIVE: To compare and standardize 2 CACFs located in Kingston, Ontario, Canada, and San Antonio, Texas, by examining participant-reported symptom severity during qualifying and treatment visits and evaluating response to treatment, while using the same allergen. METHODS: At 2 different CACFs, participants were enrolled in a double-blind, placebo-controlled, crossover intervention trial with cetirizine 10 mg. Different distribution devices delivered common short ragweed pollen via laminar air flow and maintained an airborne concentration of 3500 ± 700 grains/m3 in both facilities. A 1-hour "sham" run with no pollen release preceded a priming exposure of 3 hours and was followed 3 days later by a qualifying/treatment 5-hour exposure. At least 14 days later, another priming exposure was followed by the crossover exposure and treatment. RESULTS: Forty-eight and 43 subjects completed the study at Kingston and San Antonio, respectively. Demographics were similar. Fewer than 10% exhibited symptoms with sham exposure. No significant differences were found between the 2 facilities in maximal total rhinoconjunctivitis symptom score, total nasal symptom score, and total ocular symptom score, nor in areas under the curve. In both facilities, no significant effects of cetirizine 10 mg over placebo were detected. CONCLUSION: The results were equivalent, demonstrating that the 2 CACFs can be used together in dual-center clinical trials and show the possibility of multicenter trials involving multiple CACFs.

Full-field imaging of thermal and acoustic dynamics in an individual nanostructure using tabletop high harmonic beams.

Imaging charge, spin, and energy flow in materials is a current grand challenge that is relevant to a host of nanoenhanced systems, including thermoelectric, photovoltaic, electronic, and spin devices. Ultrafast coherent x-ray sources enable functional imaging on nanometer length and femtosecond timescales particularly when combined with advances in coherent imaging techniques. Here, we combine ptychographic coherent diffractive imaging with an extreme ultraviolet high harmonic light source to directly visualize the complex thermal and acoustic response of an individual nanoscale antenna after impulsive heating by a femtosecond laser. We directly image the deformations induced in both the nickel tapered nanoantenna and the silicon substrate and see the lowest-order generalized Lamb wave that is partially confined to a uniform nanoantenna. The resolution achieved-sub-100 nm transverse and 0.5-Å axial spatial resolution, combined with ≈10-fs temporal resolution-represents a significant advance in full-field dynamic imaging capabilities. The tapered nanoantenna is sufficiently complex that a full simulation of the dynamic response would require enormous computational power. We therefore use our data to benchmark approximate models and achieve excellent agreement between theory and experiment. In the future, this work will enable three-dimensional functional imaging of opaque materials and nanostructures that are sufficiently complex that their functional properties cannot be predicted.

Colloidal crystal order and structure revealed by tabletop extreme ultraviolet scattering and coherent diffractive imaging.

Colloidal crystals with specific electronic, optical, magnetic, vibrational properties, can be rationally designed by controlling fundamental parameters such as chemical composition, scale, periodicity and lattice symmetry. In particular, silica nanospheres -which assemble to form colloidal crystals- are ideal for this purpose, because of the ability to infiltrate their templates with semiconductors or metals. However characterization of these crystals is often limited to techniques such as grazing incidence small-angle scattering that provide only global structural information and also often require synchrotron sources. Here we demonstrate small-angle Bragg scattering from nanostructured materials using a tabletop-scale setup based on high-harmonic generation, to reveal important information about the local order of nanosphere grains, separated by grain boundaries and discontinuities. We also apply full-field quantitative ptychographic imaging to visualize the extended structure of a silica close-packed nanosphere multilayer, with thickness information encoded in the phase. These combined techniques allow us to simultaneously characterize the silica nanospheres size, their symmetry and distribution within single colloidal crystal grains, the local arrangement of nearest-neighbor grains, as well as to quantitatively determine the number of layers within the sample. Key to this advance is the good match between the high harmonic wavelength used (13.5nm) and the high transmission, high scattering efficiency, and low sample damage of the silica colloidal crystal at this wavelength. As a result, the relevant distances in the sample - namely, the interparticle distance (≈124nm) and the colloidal grains local arrangement (≈1µm) - can be investigated with Bragg coherent EUV scatterometry and ptychographic imaging within the same experiment simply by tuning the EUV spot size at the sample plane (5µm and 15µm respectively). In addition, the high spatial coherence of high harmonics light, combined with advances in imaging techniques, makes it possible to image near-periodic structures quantitatively and nondestructively, and enables the observation of the extended order of quasi-periodic colloidal crystals, with a spatial resolution better than 20nm. In the future, by harnessing the high time-resolution of tabletop high harmonics, this technique can be extended to dynamically image the three-dimensional electronic, magnetic, and transport properties of functional nanosystems.

Lack of effect of Timothy grass pollen sublingual immunotherapy tablet on birch pollen-induced allergic rhinoconjunctivitis in an environmental exposure unit.

BACKGROUND: Timothy grass pollen allergen extract tablets (Grastek) are standardized sublingual immunotherapy tablets (SLIT-T) approved for the treatment of grass pollen-induced allergic rhinitis (AR) and conjunctivitis. Many grass allergic patients are also cosensitized to birch pollen. Whether Timothy grass SLIT-T can confer symptomatic benefits for birch pollen-induced AR symptoms is unknown. OBJECTIVE: To evaluate the treatment effect of Timothy grass SLIT-T for birch pollen-induced AR in participants sensitized to both grass and birch pollen using an environmental exposure unit (EEU). METHODS: This study was a phase 4, randomized, double-blind, placebo-controlled, parallel-group study that enrolled participants aged 18 to 65 years allergic to both timothy grass and birch pollen. After a baseline EEU birch pollen challenge, in which a minimum total nasal symptom score (TNSS) of 6 of 12 was required for enrollment, participants were randomized to receive Timothy grass SLIT-T or placebo taken once daily for 4 months. No confirmatory grass pollen challenge was performed. The primary end point was the change in TNSS averaged from assessments from hours 2 to 5 during the posttreatment birch pollen challenge compared with baseline. The secondary and exploratory end points included temporally identical changes in total ocular symptom score (TOSS), total rhinoconjunctivitis symptom score (TRSS), and individual symptom scores. RESULTS: The difference in TNSS reduction after 4 months of therapy between the Timothy grass SLIT-T and placebo group was not significant (P = .83). Reductions in TOSS (P = .19) and TRSS (P = .67) were also comparable between groups. Findings between groups for individual symptom scores were similar (all P > .40), except for watery eyes, in which symptom reduction was slightly better in the placebo arm (P = .01). Timothy grass SLIT-T was well tolerated, and no serious adverse effects occurred. CONCLUSION: A bystander effect of grass SLIT-T on birch pollen-induced AR symptoms was not detected. Symptomatic benefits of grass SLIT-T are likely allergen specific. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02394600.

Clinical validation of controlled exposure to birch pollen in the Environmental Exposure Unit (EEU).

BACKGROUND: The Environmental Exposure Unit (EEU) in Kingston, Ontario, Canada is a controlled allergen challenge facility (CACF) that has been previously clinically validated for the use of ragweed and grass pollen in clinical studies. In this study we aim to validate the use of birch pollen to challenge allergic participants. METHODS: A total of 59 volunteers were screened and 38 birch allergic participants and ten non-allergics completed the study, outside of tree pollen season. Participants had to have a minimum of 2-year history of allergic rhinoconjunctivitis during the typical tree pollen season and have a positive skin prick test to birch allergen ≥5 mm from the control. Qualified participants were exposed to birch (Betula pendula) pollen for 4 h in the EEU and recorded their symptoms of sneezing, rhinorrhea, nasal congestion, nasal itch which comprised the total nasal symptom score (TNSS), as well as itchy/watery eyes, red/burning eyes and itching of ears/palate/throat which along with the TNSS comprised the total rhinoconjunctival symptom score (TRSS) along with Peak Nasal Inspiratory Flow (PNIF) at baseline and at 30 min intervals for the duration of exposure, then hourly for up to 12 h from the start of exposure. RESULTS: Allergic participants reported a gradual rise in TNSS and TRSS, reaching a mean and standard error of the mean of 7.08 ± 0.45 and 11.58 ± 0.93 respectively by 180 min from the start of exposure. Symptoms gradually declined to near baseline values following departing from the unit, reaching 1.9 and 2.7 by 450 min. Allergic participants reported significantly higher TNSS than non-allergics starting from 30 min (p < 0.01, two-way ANOVA with Bonferroni corrections), maintaining maximum significance from 60 to 300 min (p < 0.0001) and losing significance by 420 min. TRSS and PNIF followed similar trends as those seen with TNSS. Participants were phenotyped using previously published definitions using the TNSS into Early Phase Responders (EPR, 57.8 %), protracted EPR (pEPR, 39.5 %), and Dual Phase Responders (DPR, 2.7 %). CONCLUSIONS: The EEU can competently challenge birch allergic participants and achieve statistically significant changes in symptoms and nasal airflow, while such changes are not reported in non-allergic controls. Trial registration NCT02351830 clinicaltrials.gov.

Ptychographic hyperspectral spectromicroscopy with an extreme ultraviolet high harmonic comb.

We report a proof-of-principle demonstration of a new scheme of spectromicroscopy in the extreme ultraviolet (EUV) spectral range, where the spectral response of the sample at different wavelengths is imaged simultaneously. This scheme is enabled by combining ptychographic information multiplexing (PIM) with a tabletop EUV source based on high harmonic generation, where four spectrally narrow harmonics near 30 nm form a spectral comb structure. Extending PIM from previously demonstrated visible wavelengths to the EUV/X-ray wavelengths promises much higher spatial resolution and a more powerful spectral contrast mechanism, making PIM an attractive spectromicroscopy method in both microscopy and spectroscopy aspects. In addition to spectromicroscopy, this method images the multicolor EUV beam in situ, making this a powerful beam characterization technique. In contrast to other methods, the techniques described here use no hardware to separate wavelengths, leading to efficient use of the EUV radiation.

Quantitative Chemically Specific Coherent Diffractive Imaging of Reactions at Buried Interfaces with Few Nanometer Precision.

We demonstrate quantitative, chemically specific imaging of buried nanostructures, including oxidation and diffusion reactions at buried interfaces, using nondestructive tabletop extreme ultraviolet (EUV) coherent diffractive imaging (CDI). Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither visible microscopy nor atomic force microscopy can image the buried interface. Short wavelength high harmonic beams can penetrate the aluminum layer, yielding high-contrast images of the buried structures. Quantitative analysis shows that the reflected EUV light is extremely sensitive to the formation of multiple oxide layers, as well as interdiffusion of materials occurring at the metal-metal and metal-insulator boundaries deep within the nanostructure with few nanometers precision.