Amplitude-phase cross-talk cancellation in frequency domain instrumentation

Stephen P. Morgan; Kai Y. Yong

doi:10.1117/12.434536

29 June 2001 Amplitude-phase cross-talk cancellation in frequency domain instrumentation

Stephen P. Morgan, Kai Y. Yong

Proceedings Volume 4250, Optical Tomography and Spectroscopy of Tissue IV; (2001) https://doi.org/10.1117/12.434536
Event: BiOS 2001 The International Symposium on Biomedical Optics, 2001, San Jose, CA, United States

Abstract

Changes in phase that occurs with changes in amplitude impose severe limitations on the accuracy of frequency domain near infrared spectrometers. Phase is related to the photon pathlength in tissue and phase errors introduced by the instrument can be interpreted as changes in tissue oxygenation. The instrument described employs a reference RF modulated laser diode to eliminate the effects of amplitude- phase crosstalk and requires no feedback. Light from the reference and medium channels follow a common path through the detector and so the same phase error is imposed on both. Summing the reference and medium phase eliminates the crosstalk and enables the resultant to be attributed only to photon pathlength within the medium. It is also demonstrated that elimination of amplitude-phase crosstalk is a natural consequence of a phased array configuration.

Citation Download Citation

Stephen P. Morgan and Kai Y. Yong "Amplitude-phase cross-talk cancellation in frequency domain instrumentation", Proc. SPIE 4250, Optical Tomography and Spectroscopy of Tissue IV, (29 June 2001); https://doi.org/10.1117/12.434536

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