Multiple protocol fluorometer and method

A method of stimulating and analyzing a fluorescence signal in a sample, the fluorescence signal being measured to analyze parameters of the sample, said method comprising the steps of:

• (i) exciting the sample with a sequence of between 40-80 flashlets having a duration of about 0.5-1 .mu.s each and time intervals ranging from about 0.5 .mu.s to 2.0 .mu.s, to saturate PSII reaction centers in the sample within about 40-80 .mu.s;
• (ii) exciting the sample a second time with between 40-80 flashlets having a duration of about 0.125-0.5 .mu.s each and time intervals exponentially increased from about 50 .mu.s to 20 ms;
• and
• (iii) repeating steps (i) and (ii) of exciting about 15-30 times with about 40-80 flashlets, wherein total time interval of each repeated step (ii) of exciting ranges between about 200 .mu.s to 10 ms.

A method of stimulating a fluorescence signal in a sample, the fluorescence signal being measured to determine parameters of the sample, said method comprising the step of:

• exciting the sample with a sequence of N flashlets;
• measuring the fluorescence signal of the excited sample;
• and
• continuously adjusting one of N, flashlet length and time intervals between flashlets to maintain the fluorescence signal at a predetermined level.

A fluorometer for stimulating and analyzing a fluorescence signal in a sample, comprising:

• an excitation source for producing flashlets;
• a flash control circuit for controlling number, length and time interval of the flashlets;
• and
• a fluorescence detector for measuring the fluorescent light generated by the sample in response to flashlets produced by the excitation source.

A system for stimulating and analyzing a fluorescence signal in a sample comprising:

• an excitation source that generates both a sequence of flashlets and a steady state background irradiance,
• wherein the protocol includes flashlets having a duration of about 0.125 .mu.s-2.0s and time intervals between the flashlets ranging from about 0.5 .mu.s-100 .mu.s;
• an excitation control circuit that controls both the sequence of flashlets and the steady state background irradiance;
• an excitation/emission optical system that guides the flashlets to the sample and guides an emitted fluorescent light from the sample;
• a fluorescence detector that detects the emitted fluorescent light and generates a fluorescence signal;
• a data acquisition circuit that processes the fluorescence signal and generates a digitized fluorescence and reference signal;
• and
• a controller that processes the digitized fluorescence and reference signal to calculate photosynthetic parameters of the sample.