Single-exposure optical focusing inside scattering media using binarized time-reversed adapted perturbation

Light scattering inhibits high-resolution optical imaging, manipulation, and therapy deep inside biological tissue by preventing focusing. To form deep foci, wavefront-shaping techniques that break the optical diffusion limit have been developed. For in vivo applications, such focusing must provide a high gain, high speed, and a high focal peak-to-background ratio. However, none of the previous techniques meet these requirements simultaneously. Here, we overcome this challenge by rapidly measuring the perturbed optical field within a single camera exposure followed by adaptively time-reversing the phase-binarized perturbation. Consequently, a phase-conjugated wavefront is synthesized within a millisecond, two orders of magnitude shorter than the digitally achieved record. We demonstrate real-time focusing in dynamic scattering media and extend laser speckle contrast imaging to new depths. The unprecedented combination of a fast response, high gain, and high focusing contrast makes this work a major stride toward in vivo deep-tissue optical imaging, manipulation, and therapy

Single-exposure optical focusing inside scattering media using binarized time-reversed adapted perturbation

Light scattering inhibits high-resolution optical imaging, manipulation, and therapy deep inside biological tissue by preventing focusing. To form deep foci, wavefront-shaping techniques that break the optical diffusion limit have been developed. For in vivo applications, such focusing must provide a high gain, high speed, and a high focal peak-to-background ratio. However, none of the previous techniques meet these requirements simultaneously. Here, we overcome this challenge by rapidly measuring the perturbed optical field within a single camera exposure followed by adaptively time-reversing the phase-binarized perturbation. Consequently, a phase-conjugated wavefront is synthesized within a millisecond, two orders of magnitude shorter than the digitally achieved record. We demonstrate real-time focusing in dynamic scattering media and extend laser speckle contrast imaging to new depths. The unprecedented combination of a fast response, high gain, and high focusing contrast makes this work a major stride toward in vivo deep-tissue optical imaging, manipulation, and therapy

Conceptual design and progress of transmitting ∼\sim MV DC HV into 4 K LHe detectors

A dual-phase TPC (Time Projection Chamber) is more advanced in characterizing an event than a single-phase one because it can, in principle, reconstruct the 3D (X-Y-Z) image of the event, while a single-phase detector can only show a 2D (X-Y) picture. As a result, more enriched physics is expected for a dual-phase detector than a single-phase one. However, to build such a detector, DC HV (High Voltage) must be delivered into the chamber (to have a static electric field), which is a challenging task, especially for an LHe detector due to the extremely low temperature, $\sim$ 4 K, and the very high voltage, $\sim$ MV (Million Volts). This article introduces a convincing design for transmitting $\sim$ MV DC into a 4 K LHe detector. We also report the progress of manufacturing a 100 kV DC feedthrough capable of working at 4 K. Surprisingly, we realized that the technology we developed here might be a valuable reference to the scientists and engineers aiming to build residential bases on the Moon or Mars

Searching for ER and/or NR-like dark matter signals with the especially low background liquid helium TPCs

In the Dark Matter (DM) direct detection community, the absence of convincing signals has become a ``new normal'' for decades. Among other possibilities, the ``new normal'' might indicate that DM-matter interactions could generate not only the hypothetical NR (Nuclear Recoil) events but also the ER (Electron Recoil) ones, which have often been tagged as backgrounds historically. Further, we argue that ER and NR-like DM signals could co-exist in a DM detector's same dataset. So in total, there would be three scenarios we can search for DM signals: (i) ER excess only, (ii) NR excess only, and (iii) ER and NR excesses combined. To effectively identify any possible DM signal under the three scenarios, a DM detector should (a) have the minimum ER and NR backgrounds and (b) be capable of discriminating ER events from NR ones. Accordingly, we introduce the newly established project, ALETHEIA, which implements liquid helium-filled TPCs (Time Projection Chamber) in hunting for DM. Thanks to the nearly single-digit number of ER and NR backgrounds on 1 ton*yr exposure, presumably, the ALETHEIA detectors should be able to identify any form of DM-induced excess in its ROI (Research Of Interest). As far as we know, ALETHEIA is the first DM direct detection experiment claiming such an inclusive search; conventional detectors search DM mainly on the ``ER excess only'' and/or the ``NR excess only'' channel, not the ``ER and NR excesses combined'' channel. In addition, we introduce a preliminary scheme to one of the most challenging R\&D tasks, transmitting 500+ kV into a 4 K LHe detector

Pneumatic Performance Study of a High Pressure Ejection Device Based on Real Specific Energy and Specific Enthalpy

In high-pressure dynamic thermodynamic processes, the pressure is much higher than the air critical pressure, and the temperature can deviate significantly from the Boyle temperature. In such situations, the thermo-physical properties and pneumatic performance can’t be described accurately by the ideal gas law. This paper proposes an approach to evaluate the pneumatic performance of a high-pressure air catapult launch system, in which esidual functions are used to compensate the thermal physical property uncertainties of caused by real gas effects. Compared with the Nelson-Obert generalized compressibility charts, the precision of the improved virial equation of state is better than Soave-Redlich-Kwong (S-R-K) and Peng-Robinson (P-R) equations for high pressure air. In this paper, the improved virial equation of state is further used to establish a compressibility factor database which is applied to evaluate real gas effects. The specific residual thermodynamic energy and specific residual enthalpy of the high-pressure air are also derived using the modified corresponding state equation and improved virial equation of state which are truncated to the third virial coefficient. The pneumatic equations are established on the basis of the derived residual functions. The comparison of the numerical results shows that the real gas effects are strong, and the pneumatic performance analysis indicates that the real dynamic thermodynamic process is obviously different from the ideal one

Asymmetric Synthesis of Contact Sex Pheromone of <i>Tetropium fuscum</i> and Its Enantiomer

Tetropium fuscum is a harmful forest pest and attacks spruces. The contact sex pheromone of this pest, (S)-11-methyl-heptacosane, and its enantiomer were synthesized via Evans’ chiral auxiliaries. The key steps of this approach included acylation of carboxylic acid, diastereoselective methylation of oxazolidinone amide, and Wittig coupling of the aldehyde with chiral phosphonium salt. The synthetic pheromones would have potential utility in the control of this pest

Designing an Improved Strategy for Chinese Warehouses to Store Bamboo and its Semi-finished Products

Bamboo plants are fast-growing, quickly produce usable material, and are an abundant resource. Bamboo is an excellent, natural, and renewable material. It has a long history of application in human life, industrial manufacturing, cultural industries, and other fields. The warehousing of bamboo and its finished products is an emerging industry with much potential. A reasonable, stable, and orderly warehouse could be an effective solution for the sustainable management, seasonal harvesting, and raw material stability issues. In addition, the warehouse plays an important role in the processing of raw materials, reserve logistics, keeping a robust and real-time supply for downstream products. This is of great significance for alleviating problems associated with Chinese timber safety and for improving the quality of life. This paper focuses on warehousing experience in grain and coal fields, reviews the common material processing and preservation measures of bamboo, analyzes advantages and developmental prospects of bamboo warehousing, and explores and suggests appropriate storage methods, technical systems, and application models. It is expected to provide technical guidance for construction in the bamboo storage industry, and to supply ideas and suggestions for the modern development of the bamboo industry

Supplement 1: Single-exposure optical focusing inside scattering media using binarized time-reversed adapted perturbation

Supplemental document Originally published in Optica on 20 October 2015 (optica-2-10-869