scholarly journals High-speed wide-field multi-parametric photoacoustic microscopy

2020 ◽  
Vol 45 (10) ◽  
pp. 2756 ◽  
Author(s):  
Fenghe Zhong ◽  
Youwei Bao ◽  
Ruimin Chen ◽  
Qifa Zhou ◽  
Song Hu
Keyword(s):  
High Speed ◽  
Wide Field ◽  
Photoacoustic Microscopy

High-speed wide-field photoacoustic microscopy with enhanced sensitivity

2021 ◽  
Author(s):  
Hyojin Kim ◽  
Jin Young Kim ◽  
Jinwoo Baik ◽  
Seonghee Cho ◽  
Chulhong Kim
Keyword(s):  
High Speed ◽  
Wide Field ◽  
Photoacoustic Microscopy ◽  
Enhanced Sensitivity

scholarly journals Real-time whole-brain imaging of hemodynamics and oxygenation at micro-vessel resolution with ultrafast wide-field photoacoustic microscopy

2022 ◽  
Author(s):  
Junjie Yao ◽  
Xiaoyi Zhu ◽  
Qiang Huang ◽  
Anthony DiSpirito ◽  
Tri Vu ◽  
...  
Keyword(s):  
Real Time ◽  
Oxygen Delivery ◽  
High Speed ◽  
Brain Research ◽  
High Sensitivity ◽  
Wide Field ◽  
Photoacoustic Microscopy ◽  
Whole Brain ◽  
Functional Changes ◽  
Brain Hemodynamics

Abstract High-speed high-resolution imaging of the whole-brain hemodynamics is urgently needed to facilitate the next level of neurovascular research. Image acquisition speed and image quality are crucial to visualizing real-time hemodynamics in complex brain vascular networks, and displaying fast pathophysiological dynamics on a micro and macro-level, enabling advances in current queries in neurovascular and brain metabolism research, including stroke, dementia and acute brain injury. Further, real-time oxygen saturation of hemoglobin (sO2) imaging to differentiate arteries from veins and capture fast-paced oxygen delivery dynamics is needed to solve pertinent questions in these fields and beyond. Here, we present a novel ultrafast functional photoacoustic microscopy (UFF-PAM) to image the whole-brain hemodynamics and oxygen delivery. UFF-PAM takes advantage of several key engineering innovations, including Raman-shifter-based dual-wavelength laser excitation, water-immersible 12-facet-polygon scanner, high-sensitivity ultrasound transducer, and deep-learning-based image upsampling. A volumetric imaging rate of 2 Hz has been achieved over a field of view (FOV) of 11× 7.5 × 1.5 mm3 with a high spatial resolution of ~10 µm. Using the UFF-PAM system, we have demonstrated proof-of-concept functional studies on the mouse brains in response to systemic hypoxia, sodium nitroprusside, and stroke. We observed the mouse brain’s fast morphological and functional changes over the entire cortex, including vasoconstriction, vasodilation, and deoxygenation. More interestingly, for the first time, under the whole-brain FOV and micro-vessel resolution, we captured the vasoconstriction and oxygenation change simultaneously in the spreading depolarization (SD) wave. Our work provides a great potential for fundamental brain research under various pathological and physiological conditions.

scholarly journals Wide-field fast-scanning photoacoustic microscopy based on a water-immersible MEMS scanning mirror

2012 ◽  
Vol 17 (8) ◽  
pp. 1 ◽  
Author(s):  
Junjie Yao ◽  
Lidai Wang ◽  
Joon-Mo Yang ◽  
Liang S. Gao ◽  
Konstantin I. Maslov ◽  
...  
Keyword(s):  
Wide Field ◽  
Photoacoustic Microscopy ◽  
Scanning Mirror

The Compression-Ignition Engine and Its Applicability to British Railway Traction

1933 ◽  
Vol 124 (1) ◽  
pp. 3-61 ◽  
Author(s):  
L. F. R. Fell
Keyword(s):  
Internal Combustion Engine ◽  
High Speed ◽  
Combustion Engine ◽  
Internal Combustion ◽  
High Rate ◽  
Wide Field ◽  
Compression Ignition ◽  
Electric Locomotive ◽  
Compression Ignition Engine ◽  
Railway Traction

The author considers that, while the internal combustion engine is not universally applicable to British railway traction, there is a wide field which can be more economically covered by the oil engine than by other means. Electric transmission is, in spite of high first cost, the most readily adaptable for use in conjunction with the oil engine, and possesses a balance of advantages over all other known systems. The oil-electric locomotive offers a long list of important advantages for railway operation not possessed by other systems. These advantages are, however, offset by high first cost for powers of 1,000 b.h.p. and over. A comparison is drawn between the first cost of steam and oil-electric locomotives for the various duties called for in the service of a British railway. This shows that, while the first cost of the oil-electric main line express passenger locomotive is three times that of the existing steam locomotive, the first costs of branch passenger, medium goods, and shunting steam and oil-electric engines are comparable. This is owing to the cost per brake horse-power required diminishing with increase of size in the case of the steam locomotive, whereas it remains constant in the case of the oil-electric. Owing to the high rate of acceleration necessary the use of the oil-electric system is considered unsuitable as a substitute for dependent electrification of suburban lines. The railway oil engine is a specialized requirement. It must be of the high-speed type running at speeds of up to 1,500 r.p.m., in order to reduce first cost and for other reasons. Details are given of various types of British compression-ignition engines which are considered suitable for British railway work. The author deduces that an engine of twelve-cylinder “V” type and an engine with six cylinders in line, both incorporating the same design and size of cylinder, would fill all the requirements which can be economically met by the oil engine on a British railway. He selects the single sleeve-valve engine design as having the greatest balance of advantages in its favour for railway purposes. Attention is drawn to the importance of simplifying the installation of the compression-ignition engine and various suggestions are put forward to this end. In conclusion the author stresses the importance of the railway companies giving a lead to the internal combustion engine industry as to the railway requirements in size and type of engine, and states that it is the purpose of his paper to assist those concerned in arriving at this immediately important decision.

scholarly journals High-speed high-resolution laser diode-based photoacoustic microscopy for in vivo microvasculature imaging

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiufeng Li ◽  
Victor T C Tsang ◽  
Lei Kang ◽  
Yan Zhang ◽  
Terence T W Wong
Keyword(s):  
High Resolution ◽  
High Speed ◽  
High Performance ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Cost Effective ◽  
High Signal ◽  
Photoacoustic Microscopy ◽  
Mouse Ear

AbstractLaser diodes (LDs) have been considered as cost-effective and compact excitation sources to overcome the requirement of costly and bulky pulsed laser sources that are commonly used in photoacoustic microscopy (PAM). However, the spatial resolution and/or imaging speed of previously reported LD-based PAM systems have not been optimized simultaneously. In this paper, we developed a high-speed and high-resolution LD-based PAM system using a continuous wave LD, operating at a pulsed mode, with a repetition rate of 30 kHz, as an excitation source. A hybrid scanning mechanism that synchronizes a one-dimensional galvanometer mirror and a two-dimensional motorized stage is applied to achieve a fast imaging capability without signal averaging due to the high signal-to-noise ratio. By optimizing the optical system, a high lateral resolution of 4.8 μm has been achieved. In vivo microvasculature imaging of a mouse ear has been demonstrated to show the high performance of our LD-based PAM system.

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