Phase-Locked Detection of Fluorescence Lifetime

Phase-Locked Detection Using a Single Reference Signal 

In the system which uses crystalline alexandrite as the sensor material/381 a measurement reproducibility of 1 °C is achieved over a wide temperature region from 20 to 700°C. The same technique is applied to another fiber optic thermometer system which is designed for biomedical sensing applications and uses LiSrAlF6 Cr3+ as sensor material/391 The standard deviation of the measurement recorded by this system is better than 0.01°C within the 20 Cand 50°C region. 

The easing of the requirement for high-quality optics by using this two-reference technique, and employing those characteristics which are essentially inherent to the 

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Figure 11.10. Phase-locked detection of fluorescence lifetime using single reference signal. FID = fluorescence inducing and detecting devices LPF = low-pass electronic filter VCO = voltage-controlled oscillator v, = signal to modulate the output intensity of the excitation light source v/= the fluorescence signal.

Nd YAG and the lifetime measurement is made by the use of the phase-locked detection of fluorescence lifetime (PLD) scheme. By reference to the use of the fluorescence lifetime measurement, the problems, in pyrometry, of emissivity, and sight path factor in the blackbody radiation measurement could be corrected in such a scheme having an internal self-calibration. ... 

Abbreviations LD = laser diode PLD = phase-locked detection of fluorescence lifetime rr = lifetime deviation. 

Z. Y. Zhang, K. T. V. Grattan, and A. W. Palmer, Phase-locked detection of fluorescence lifetime and its thermometric applications, in Int. Conf. Biomedical Optics 93, Los Angeles, January 1993. SPIE Proc. 1885, 228-239 (1993). 

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