Measurement of fluorescence
AssigneeLuminis Pty. Ltd.
InventorsRichard J. Norrish, Joseph T. Wiskich
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Abstract
A fluorometer probe head and a method of operating a probe to overcome problems of reflectance. A preferred embodiment for determination of chlorophyll in plant leaves uses a red LED and a green LED consecutively directed to a particular target spot and a photodiode records fluoresced and reflected signals to provide an accurate result.
Claims12
A method of determining the instantaneous or transient fluorescence of a test sample at a test point, comprising the steps of
- (a) determining the gross reflectance and fluorescence value of a sample at a test point when excited by light from a first light emitting diode at a first known wavelength which causes at least fluorescence in the sample,
- (b) determining the reflectance at the test point by irradiating the sample with light from a second light emitting diode at a second wavelength which is known but different from the first wavelength and which does not cause fluorescence in the sample and
- (c) subtracting the reflectance from the gross reflectance and fluorescence value to give the fluorescence at the test point,
- wherein a single detector is used to make the determinations of steps (a) and (b).
A detector head for a device for measuring instantaneous or transient fluorescence, comprising a pair of light emitting diodes, the first of which is a red LED having a bandwidth of 655 to 677 nm and the second of which is a green LED having a bandwidth of 556 to 580 nm, positioned to provide respective emitted signals to a test point on a surface to be tested, and one detector positioned to receive reflected and fluoresced signals from the diodes from the test point.
Dependencies are inferred from the claim text.