What is a Spectrophotometer?
An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum. Compact optical spectrophotometers can typically measure the intensity of light at specific wavelengths from 200 to 2500 nanometers. Modern compact optical spectrophotometers are fully digital devices and the light spectrum is stored in computer memory. Advances in reducing the size of the spectrometer have enabled handheld/portable applications in addition to the traditional environment of the laboratory. Spectrometers are now present as critical components of mass produced instruments for many industries including medical, food, energy, research, and education.
The variable measured is most often the light’s intensity but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light or a unit directly proportional to the photon energy, such as wavenumber or electron volts, which has a reciprocal relationship to wavelength. A spectrophotometers is used in spectroscopy for producing spectral lines and measuring their wavelengths and intensities. Spectrophotometers is a term that is applied to instruments that operate over a very wide range of wavelengths, from gamma rays and X-rays into the far infrared. If the instrument is designed to measure the spectrum in absolute units rather than relative units, then it is typically called a spectrophotometer. The majority of spectrophotometers are used in spectral regions near the visible spectrum.