Abstract
We described a low-cost, frequency-domain photon migration spectroscopy instrument by using in-phase and quadrature demodulation technique in a 140-MHz homodyne system. A time constant of 1 ms was obtained. A frequency-division multiplexing technique was used for multiposition or multiwavelength applications, such as for tissue oximetry. By conducting several experiments on tissue/blood models, we show that the optical properties of tissue can be determined with this system by either using multiple source-detector separations at accuracy better than 8% or using single source-detector separation. The accuracy with the latter method can be improved to be 10% or better by choosing a proper calibration sample. A frequency-sweep system (30 to 700 MHz) was also implemented; the phase and amplitude measured on a tissue-like solution at 780 nm agreed to their theoretical values within 5% and 10% accuracy, respectively.
Original language | English (US) |
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Pages (from-to) | 1562-1569 |
Number of pages | 8 |
Journal | Optical Engineering |
Volume | 36 |
Issue number | 5 |
DOIs | |
State | Published - May 1997 |
Externally published | Yes |
Keywords
- Absorption and scattering coefficients
- Frequency-division multiplex
- Frequency-domain spectroscopy
- In-phase and quadrature demodulation
- Noninvasive tissue oximetry
- Photon migration
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- General Engineering