(redirected from fluorometers)
Also found in: Dictionary, Medical.


An instrument that measures the fluorescent radiation emitted by a sample which is exposed to monochromatic radiation, usually radiation from a mercury-arc lamp or a tungsten or molybdenum x-ray source that has passed through a filter; used in chemical analysis, or to determine the intensity of the radiation producing fluorescence. Also spelled fluorimeter.



(also fluorimeter), an instrument used for measuring the decay time τ of fluorescence, which is approximately 10–8–10–9 sec. A fluorometer operates on the following principle. During high-frequency modulated excitation of luminescence, the luminescence is modulated at the same frequency as the excitation; however, because of the finite duration of the luminescence emission, the phase of the luminescence modulation lags behind that of the excitation modulation. In the case of excitation that is sinusoidally modulated at a frequency ω and fluorescence that decays exponentially, the phase angle φ = tan–1 (ωτ). The relation between the amplitude A0 of the excitation modulation and the amplitude A of the luminescence modulation is Fluorometer. Thus, to determine τ either φ or the ratio A0/A must be measured. If the decay is not exponential, the same method may be used to establish the mean lifetime of the excited state and to estimate the extent to which the decay is not exponential.

Figure 1. Schematic diagram of a phase fluorometer

The most widely used fluorometers are phase fluorometers, which measure φ (Figure 1). In an optical-excitation phase fluorometer, a light beam from a source (1) is focused on a modulator (2). A portion of the modulated flux is deflected by a semi-transparent plate (3) and enters a photomultiplier (5). The remainder of the flux is focused on a specimen (4) to excite fluorescence, which is deflected to another photomultiplier (6). The phase difference φ between the photoelectric currents from (5) and (6) is measured by means of a phase meter (7). A cathode-ray tube or phase detector (8) serves as the phase indicator. Fluorometers based on electron-beam and X-ray excitation have also been developed.

In an instrument that is more advanced than a fluorometer, luminescence is excited by short light pulses, and the decay curve is recorded directly.

Instruments that are used for luminescence analysis are also called fluorometers, or fluorimeters. Such instruments measure the intensity of luminescence and contain both a source for exciting the luminescence and a photometer.

References in periodicals archive ?
These values were determined using data collected by the submersible fluorometers at the sentinel stations.
Thus, in most current field fluorometers, in which the light flashes utilized induce multiple turnovers of PSII, one can consider the PQ pool as the terminal sink for the electrons extracted from water at PSII.
Readings from the two fluorometers also were compared side-by-side at the beginning of each deployment and again after the last set of readings was taken to be sure they gave similar readings.
Turner Designs is known for rugged, reliable and stable submersible, field, handheld, laboratory, and in-line fluorometers and turbidimeters, varying in functionality, size, and price.
Mountain View, CA 3/7/06--Reflect Scientific, a supplier of lab equipment, has signed a letter of intent to acquire JMST Systems, a maker of UV-Vis detectors and fluorometers as well as the CEC-20 capillary electrophoresis system.
The output signal from the indicator organism can be adapted to match existing instruments such as fluorometers, colorimeters, or luminometers.
PTI is the world leader in microscopy based fluorometers, especially for ion imaging, in part due to a long-standing research and development collaboration with a prestigious laboratory in the Faculty of Medicine and Dentistry of the University of Western Ontario in Ontario, Canada.
Cyclops Fluorometers can also be configured with custom optics for specialized applications per customer request.
Spectrofluorometers and multi-functional fluorometers are seeing some growth, but many users have shifted to microplate-reader formats.
Calibration of x-ray fluorometers is accomplished using lead-doped plaster of Paris phantoms.
Turner offers microplate and single tube reader luminometers, fluorometers, photometers and multimode instruments for life science labs.
com)-- Turner Designs' new Cyclops Integrator enables easy system integration of their popular Cyclops Submersible Fluorometers and Turbidimeter into AUVs, gliders, floats and other platforms.