Abstract: A luminescence based analytical probe is excited with light varying repetitively in amplitude at multiple modulation frequencies. A composite signal incorporating components at a plurality of these modulation frequencies, produced by emissions in all of the various decaying modes is analyzed to provide information, such as the fractional luminescence contribution and/or lifetime of each individual decaying mode because the various decaying mode are segregated by analysis of the composite signal, there is no need to segregate light from the various decaying mode according to the wavelength of the light. Therefore, the probe may incorporate plural luminescent materials which have different decay modes with different luminescent decay times and sensitive to different conditions to be monitored, even if the plural luminescent materials absorb and emit light at the same wavelengths.

Abstract: Apparatus and methods for measuring response of a chemical composition to light, as by frequency domain, phase angle, or modulation fluorometry and/or phosphorimetry. Pulsed light having a known fundamental frequency is applied to the composition thereby eliciting response light varying at the fundamental frequency and at harmonics thereof. The response light signal may be sampled according to a wave-skipping sampling scheme, and the sampled response signal may be transformed into a frequency domain representation, as by a digital fast Fourier transform technique. A reference signal derived from the excitation light may be similarly processed and the results used as a basis for comparison to derive properties of the chemical composition such as phase and modulation response of the composition to the fundamental and harmonic frequencies. The invention provides rapid monitoring and determination of luminescence characteristics.

Abstract: A fiber optic probe incorporating a luminescent composition is used to monitor conditions within a living subject. Response light from the fiber optic is detected and a frequency domain representation of the response light is derived. Characteristics of the frequency domain representation are used to derive values for luminescence lifetimes or similar decay parameters and these values in turn are translated into values of the conditions to be sensed.