High-precision frequency-domain measurements of the optical properties of turbid media

1999 ◽  
Vol 24 (14) ◽  
pp. 930 ◽  
Author(s):  
Martina Gerken ◽  
Gregory W. Faris
Author(s):  
Lelia Adelina Paunescu ◽  
Maria Angela Franceschini ◽  
Sergio Fantini ◽  
Albert E. Cerussi ◽  
Enrico Gratton

2013 ◽  
Vol 329 ◽  
pp. 364-367
Author(s):  
Li Mian Ren ◽  
Li Xia Wang ◽  
Ming Zhe Wei

Frequency meter measured frequency of analog periodic signal in its frequency domain and used the software control program to replace the complex outside counting circuit. ARM7 development board, LPC2103 chip, and AD9833 chip made up of a complete system. This paper gave the designing schemes of hardware and software system and analyzed experiment results, which prove that this design reaches expectant target with less hardware and simpler structure.


2001 ◽  
Vol 40 (22) ◽  
pp. 3810 ◽  
Author(s):  
George Alexandrakis ◽  
David R. Busch ◽  
Gregory W. Faris ◽  
Michael S. Patterson

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yanyu Zhao ◽  
Bowen Song ◽  
Ming Wang ◽  
Yang Zhao ◽  
Yubo Fan

AbstractThe ability to quantify optical properties (i.e., absorption and scattering) of strongly turbid media has major implications on the characterization of biological tissues, fluid fields, and many others. However, there are few methods that can provide wide-field quantification of optical properties, and none is able to perform quantitative optical property imaging with high-speed (e.g., kilohertz) capabilities. Here we develop a new imaging modality termed halftone spatial frequency domain imaging (halftone-SFDI), which is approximately two orders of magnitude faster than the state-of-the-art, and provides kilohertz high-speed, label-free, non-contact, wide-field quantification for the optical properties of strongly turbid media. This method utilizes halftone binary patterned illumination to target the spatial frequency response of turbid media, which is then mapped to optical properties using model-based analysis. We validate the halftone-SFDI on an array of phantoms with a wide range of optical properties as well as in vivo human tissue. We demonstrate with an in vivo rat brain cortex imaging study, and show that halftone-SFDI can longitudinally monitor the absolute concentration as well as spatial distribution of functional chromophores in tissue. We also show that halftone-SFDI can spatially map dual-wavelength optical properties of a highly dynamic flow field at kilohertz speed. Together, these results highlight the potential of halftone-SFDI to enable new capabilities in fundamental research and translational studies including brain science and fluid dynamics.


2010 ◽  
Vol 36 ◽  
pp. 344-348
Author(s):  
Guo Hong Fu ◽  
Bin Xiong

A new medium-power frequency domain IP transmitter is developed in this paper, which uses the IP rectangle drive signal with high precision and good stability produced by CPLD and GPS punctual module, and adopts the four bridge legs of the new IPM to compose full bridge inverter switch. Experimental results show that this transmitter has many advantages, such as high precision frequency, high transmitting power, extremely good stability, portable and very good application effects.


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