PHOTOMETER

Although this is basically a device for measuring light intensity, in medical work it is normally associated with clinical chemistry equipment used for determining the concentration of particular chemicals in samples of body fluids. They are found in fluorimeters, spectrophotometers, colorimeters, flame photometers, atomic absorption spectrometers and in automated chemical analysers.

The basic device consists of a light-detection mechanism which uses a photomultiplier tube or semiconductor device, and this is coupled to an electronic display and recording system which may include extra components to assist in identifying the wavelengths of light involved (in this case it should be called a spectrophotometer). When used in conjunction with any of the instruments mentioned above, three extra components are required, which are a light source, a wavelength selector (which may be a filter or monochromator) to select a particular wavelength or range of wavelengths, and a sample chamber or cuvette. The light power detected by the photometer shows the amount of absorption or emission of radiation at the particular wavelength selected. By comparison with a cuvette containing a blank or calibration sample, the concentration of the test sample can be estimated.

Content and Design Copyright 2000 Dr. Malcolm C Brown.  See Title Page for more details