Near- and Extended-Edge X-Ray-Absorption Fine-Structure Spectroscopy Using Ultrafast Coherent High-Order Harmonic Supercontinua

Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6  keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K- and L-absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 10^{9}  photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 10^{26}  photons/s/mrad^{2}/mm^{2}/1% bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to-attosecond time scales and picometer length scales.093002

Statistically biased calibration method for the real-time adjustment of noninvasive haemoglobin measurements in a semiautomated infusion system

Closed loop systems are the ultimate solution to ensure that optimal therapies are delivered in a timely manner. A concept of a semi-closed loop infusion system for perioperative semi-automated optimisation of blood pressure and haemodilution is proposed. The key variable for the latter objective is the noninvasively and continuously measured blood haemoglobin concentration. However, it lacks reliability in predicting the haemoglobin in large blood vessels. Our proposed statistically biased calibration method for the adjustment of noninvasively measured Hb enabled better prediction of arterial Hb when it was applied to data from our ongoing clinical trial

Generation of a single UV pulse from a near-IR pulse burst

Date of Conference: 25-29 June 2017 in Munich, GermanySummary form only given. High harmonic generation (HHG) requires high peak-power laser sources. Most of the well-known high peak power lasers are operating in the near-IR wavelength region. Recently it was demonstrated that HHG can be effectively phase matched in the soft X-ray region by using very high intensity UV lasers and multiply charged ions [1]. High average and high peak power UV sources operating around and below 280 nm are required for many other applications, such as ablation in ophthalmology, materials processing and photoelectron spectroscopy. Due to lack of ultrafast high peak power lasers operating in UV, generation of ultrashort UV pulses is possible by up-converting frequency of near-IR laser. This can be done by cascaded harmonic generation in nonlinear crystals with efficiency higher than 40% [2]. However, to obtain high pulse energies in UV region, high energy IR pump is necessary. This becomes increasingly difficult for femtosecond laser pulses because of the optical damage problem in CPA systems. Very high pulse stretching rates in the CPA become unfeasible due to the limited size of dispersive optics. Alternatively, the intensity in the laser cavity can be decreased by using a pulse burst which effectively increases the pulse duration. Therefore, this approach is also suitable for increasing energy throughput in fiber delivery and fiber post compression schemes [3]. © 2017 IEEE

Supplement 1: Hollow-core-waveguide compression of multi-millijoule CEP-stable 3.2 μm pulses

Supplementary material Originally published in Optica on 20 December 2016 (optica-3-12-1308

Multi-millijoule Few-Optical-Cycle Pulses in Mid-IR: Scaling Power, Energy and Wavelength

We discuss prospects of the generation of high power mid-IR pulses by analyzing soliton self-compression of multi-mJ 4-μm pulses and the development of few-optical-cycle 6-μm optical parametric amplifier. Scalability of pump lasers is addressed

Revised evaluation of hemodilution response in the semi-closed loop infusion system

A mini volume loading test (mVLT) method is used for decision making in our prototype semi-closed loop infusion system (SCLIS). The mVLT fluid protocol consists of hemodilution response-guided mini fluid challenges. Each mini fluid challenge (MFC) consists of a 2.5 ml kg-1–5 ml kg-1 crystalloid bolus infused over 2 min–5 min and followed by a 5 min period with no fluids. Arterial plasma dilution efficacy (aPDE) of a MFC is calculated from invasively measured hemoglobin (aHb) before and after each MFC. Capillary plasma dilution efficacy (cPDE) is calculated from non-invasively measured hemoglobin (SpHb). The zero or negative arterio-capillary plasmadilution efficacy difference (acPED ≤ 0 p.d.u.) is an indication of hemodilution non-response and imminent edema. However, it requires both invasive and non-invasive hemoglobin measurements. A non-invasive assessment of hemodilution response within the mVLT method would increase its practical application and reduce costs further enhancing its applicability in the SCLIS. This possibility exists if the cPDE could reliably predict the acPED value or the hemodilution response (the presence of acPED within a range of > 0) or non-response (acPED ≤ 0). We report a retrospective observational study in an elective total knee arthoplasty (TKA) setting. The 2.5 ml kg-1 boluses were used in six MFCs in both pre- and post-operative mVLT sessions. The primary objective was to assess the accuracy of cPDE in predicting the hemodilution response using the receiver operating characteristic (ROC) curve and gray zone approaches. Our secondary objective was to investigate the feasibility of a statistical optimization method (SOM) in predicting the acPED. The analysis included 480 paired values of cPDE and acPED. The best cut-off value for cPDE was 0.015 p.d.u. (specificity = 0.84, sensitivity = 0.90). [...

Near- and Extended-Edge X-Ray-Absorption Fine-Structure Spectroscopy Using Ultrafast Coherent High-Order Harmonic Supercontinua.

Recent advances in high-order harmonic generation have made it possible to use a tabletop-scale setup to produce spatially and temporally coherent beams of light with bandwidth spanning 12 octaves, from the ultraviolet up to x-ray photon energies >1.6  keV. Here we demonstrate the use of this light for x-ray-absorption spectroscopy at the K- and L-absorption edges of solids at photon energies near 1 keV. We also report x-ray-absorption spectroscopy in the water window spectral region (284-543 eV) using a high flux high-order harmonic generation x-ray supercontinuum with 10^{9}  photons/s in 1% bandwidth, 3 orders of magnitude larger than has previously been possible using tabletop sources. Since this x-ray radiation emerges as a single attosecond-to-femtosecond pulse with peak brightness exceeding 10^{26}  photons/s/mrad^{2}/mm^{2}/1% bandwidth, these novel coherent x-ray sources are ideal for probing the fastest molecular and materials processes on femtosecond-to-attosecond time scales and picometer length scales