Photoelectric microscopy with optical resolution (OR-PAM), a new method of hybrid imaging, allows us to listen to the sound of light and see its own biological color. Can be used for live, multi-segment action images, but most commercial lasers have limited wavelength option and the limitations of existing scanning methods have meant that OR-PAM can only have one or two of different types obtained in one scan. These constraints have given time to multivariate action images, and it has been difficult to capture the dynamic changes of action information in biological tissues.
To overcome these limitations, Lidai Wang and his research team at the City University of Hong Kong recently developed a multiwavelength OR-PAM system based on a single laser source. As reported in Advanced Photonics, the novel system enables simultaneous multicontrast imaging of hemoglobin concentration, blood flow rate, blood oxygen absorption, and lymphatic density. This action information can provide large subcellular insights to scientists studying disease models, for example in cancer research.
Photocoustic microscope with optical solution
Based on the intrinsic properties of the targeted biological material, photocoustic images take advantage of the fact that when a print is focused by a pulsed laser beam, it absorbs light and generates light. immediate heat. That heat causes thermal expansion, which generates an ultrasonic mechanical wave, called the photoacoustic wave (PA). After collecting the PA wave with an ultrasonic transducer and reconstructing the signal, scientists can obtain an image showing the light circulation in a biological print.
Photoelectric microscopy with optical resolution provides high-resolution and high-interface image information for the structure, morphology, function, and metabolism of biological tissues, with the expectation of wide applications in biomolecular imaging.
Five-wave fiber laser source
Wang’s team has developed OR-PAM by developing a five-wave fiber laser source based on a single-wavelength nanosecond laser source. The transition time among different waves occurs on a submicrosecond timeframe, which opens up opportunities for multitasking OR-PAM simultaneously. Wang’s team tested the stability of the system by measuring the variability of energy and motion, and tested the depth of images, as well as the lateral and axial resolution for OR-PAM images.
According to Wang, the system is based on the influence of scattered Raman (SRS). Basically, the pumped laser source can generate a scattered laser beam with a wavelength beyond the original incident behavior through the optical fiber. When the energy of the pumped laser source exceeds a certain threshold, the generated SRS wavelength maintains high conductivity, high monochromaticity, and high coherence, which makes it highly adaptable as an OR-PAM laser source. The multi-scatter scatter waves can be used for photoacoustic multi-wavelength images.
Multifunctional imaging and disease modeling
Wang’s team also developed a multiparameter image processing method for calculating diameter, depth, tortuosity, and other physiological parameters in microvascular vessels, providing the basis of image analysis for modeling disease. Using the five-wave OR-PAM, the research team performed more multifactorial images of tumor development, lymphatic clearance, and brain imaging.
In their first step, they performed multifactorial microscopic imaging of small animals in vivo, including hemoglobin density, blood flow rate, oxygen absorption, and lymphatic density. They also studied morphological and functional differences (including diameter, blood flow, blood oxygen level, etc.) of different blood vessels in the imaging range.
Because traditional multifunctional OR-PAM requires multiple scanning and multiple laser sources to achieve these results, their work has addressed two major problems. One is that the microenvironment of blood vessels in the tension changes with time, so long-term multiple scans cause inconsistencies in action images. The other is the asynchrony among the various laser sources. Such variables cause systematic errors in calculation. This new method can produce multi-functional images with a single laser source and in a single scan, which not only greatly shortens the image time, but also improves the accuracy of images .
Wang says, “In the future, by making the best use of the scanning method, and combining the ORiw-PAM multiwavelength in this work, real-time images of the changes can be made dynamics for realizing cognitive parameters in some disease models. “
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Read the open access research article by Chao Liu et al., “Five-wave resolution photoelectric microscope of blood and lymphatic vessels,” Adv. Photon. 3 (1), 016002 (2021), doi 10.1117 / 1.AP.3.1.016002
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