Optics: measuring and testing – Blood analysis
Patent
1992-04-24
1994-03-08
Rosenberger, Richard A.
Optics: measuring and testing
Blood analysis
435 34, 435808, 356338, G01N 3348
Patent
active
052932109
ABSTRACT:
Methods and apparatus for detecting bacteria in samples using time-resolved light scattering and absorption measurement are disclosed. The present invention provides a system wherein a plurality of samples may be tested by providing a modulated excitation signal which is introduced into each sample and collected at a point disposed across each sample. The amplitude and phase of the collected signal are then processed to determine the time characteristics, modulation and phase of the signal after it has passed through the sample. By comparing time characteristics, modulation and phase with the time characteristics, modulation and phase collected at a previous point in time or alternatively from a sample known to be free of bacteria, the presence of bacteria may be determined, since it has been found that the presence of bacteria causes a significant change in the time characteristics, modulation and phase. Preferably, diode lasers are used to introduce modulated electromagnetic radiation into the samples and a multichannel plate photomultiplier tube is used to provide a signal from which the phase and amplitude can be determined. Alternatively, in other embodiments of the present invention the modulated electromagnetic radiation may be introduced using an optical switch and the multichannel plate photomultiplier tube may be replaced by avalanche photodiodes disposed against each sample that also create a signal containing time-averaged intensity, amplitude, and phase information.
REFERENCES:
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patent: 4516858 (1985-05-01), Gelbwachs
patent: 5119815 (1992-06-01), Chance
K. Berndt, et al., "Picosecond laser spectroscopy with avalanche photodiodes," SPIE-The International Society for Optical Engineering, vol. 909 Time-Resolved Laser.
J. R. Lakowicz, et al., "Frequency-Domain Measurements of Photon Migration in Tissues," Chemical Physics Letters, (1990), vol. 166, No. 3, pp. 246-252.
Klaus W. Berndt, et al., "Phase-modulation fluorometry using a frequency-doubled pulsed laser diode light source," Rev. Sci. Instrum., 61(7), Jul. 1990, pp. 1816-1820.
K. Berndt, "Opto-electronic high-frequency cross-correlation using avalanche photodiodes," Measurement, vol. 5, No. 4, Oct-Dec. 1987, pp. 159-166.
Becton Dickinson and Company
Fiedler Alan W.
Rosenberger Richard A.
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