Computer controlled fluorometer device and method of operating same

. A computer controlled fluorometer device for conveniently making rapid and accurate measurements of plant or phytoplankton photosynthetic parameters including ranges of variable fluorescence, .DELTA..phi..sub.sat, absorption cross section, .sigma.(PSII), decay kinetics of variable fluorescence, and levels of energy transfer between PSII units in either essential darkness or under background illumination, comprising:

• (a) a pump flash source, a probe flash source, a sample chamber having a cavity for containing a sample of plant or phytoplankton to be measured, a programmable computer means including a microprocessor, and data and address bus means and D/A converters for operatively connecting said computer means to enable the computer means when programmed to control energy, increment, repetition, and sequencing of both said pump flash source and said probe flash source;
• (b) light filter, collimator, and reflector means arranged in operating relationship between said pump flash source and the sample chamber, and between said probe flash source and the sample chamber, for directing pump flashes and probe flashes, produced, respectively, by said flash sources, into the sample chamber;
• (c) a light condenser lens system, emission filters, and a fluorescence detector with a photomultiplier (PMT) arranged in series to collect light emitted from said sample chamber and direct it into the PMT, said PMT being operable to produce a signal that corresponds to said light directed into the PMT, the operation of said PMT being controlled by a power supply that is operably connected to it and to said computer means from which control signals are transmitted to the power supply;
• (d) signal conditioning unit and two flash monitoring means, each operatively connected, respectively, to monitor pump flash light each probe flash light generated by said flash sources, said monitoring means being further operably connected to transmit signals corresponding to said monitored flashes to said signal conditioning unit, said signal conditioning unit being operably connected to be controlled by, and to transmit signals to, said microprocessor;
• (e) a software programmable source of background irradiance, said programmable source being operably connected to receive programmed signals from said microprocessor, and being arranged to emit light into said sample chamber;
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• (f) a computer program installed to run said microprocessor, thereby to control the operation of said flash sources, said power supply controlling the PMT, and said signal control unit, to enable the fluormeter device to make said measurements, said computer program being further operable to control said computer means to collect, analyze, and store data relating to said measurements.