Fluorometers are instruments that measure the amount of fluorescent radiation produced by a sample exposed to monochromatic radiation. They contain filters for excitation and emission but no wavelength scanning. Light is collected at 90 degrees from the incident light (excitation) direction. Fluorescence is a very reliable and accurate means for quantifying and detecting a compound or substance. It is a phenomenon in which light energy is absorbed by a molecule and then re-emitted again as a photon of light with a slightly longer wavelength. The phenomenon is common among organic molecules including groups of strongly fluorescent dyes, such as fluorescein (absorbs blue, emits yellow-green light), the rhodamines (absorb green light, emit orange-red), and the family of stilbene optical brighteners, which absorb U/V light and emit blue. Fluorescence has become an indispensable tool in a wide range of research disciplines such as: molecular and cellular biology, genetics, environmental assessment, pharmaceutics, forensics, food processing, oceanography, and biohazard detection. Fluorometers are also sometimes referred to as luminescence spectrometers, fluorimeters, fluorescence spectrometers or spectrofluorometers.
The important parameters measured by fluorometers are the spectral or wavelength range and the accuracy and resolution of that reading. Common detector configurations of fluorometers include photomultiplier tubes and photodiodes. A photomultiplier tube is a photo-detector, with adjustable voltage, that translates optical tube (PMT) signals into electrical current. Increasing the PMT voltage increases the output signal for a given amount of light. A photodiode is a semiconductor device used to detect light and generate an electrical current. Photodiode detectors are typically used in forward scatter (FSC) detection.
Fluorometers can be configured for either continuous or flow through monitoring to monitor samples on a process line or in-situ in the field. Fluorometers can also be configured to monitor single samples. The samples are individually injected into the fluorometer.
Common features for fluorometers include shutters, microscope, automatic temperature compensation ability, temperature measurement ability, programmability, self-calibration and alarms.