Definition : Instruments designed to measure the radiant flux (also known as radiant power) in a predetermined spectral range. Classical radiometers measure the thermal effect produced by radiation falling on the instrument, using a sensor that absorbs radiation and increases its temperature accordingly (frequently called a bolometer). The temperature increase is measured with a thermometer attached to the bolometer. Radiometers intended for the measurement of light radiation usually include a semiconductor diode that produces mobile electric charges when struck by photons (i.e., photodiodes) and a voltage or current meter; they are intended for measuring light in different ranges of the spectrum (e.g., visible, infrared, ultraviolet) within a given power range, accuracy, resolution, and/or other parameters. These instruments also include a display showing the results in either analog or digital format. To obtain accurate measurements, radiometers should be manufactured according to the source of light to be measured (e.g., lamp, LED, laser), the transmission medium (e.g., air, water, fiber optics), and the characteristics of the detector chosen. Power is typically measured in watts, and power density in watt/cm2. Most radiometers used for clinical purposes are intended to measure light radiation during phototherapy procedures and/or to assess the light intensity emitted by light sources (e.g., lamps, LEDs, fiber optics); dedicated instruments used to measure light intensity during therapeutic (e.g., bilirubin, skin) treatments and laboratory procedures and/or from light sources (e.g., germicidal lights, lasers) are available.
UMDC code : 16348