Spectrometer

A spectrometer shines a light on a sample and measures how much light is absorbed at a specific wavelength. Knowing how much light is absorbed can help scientists identify the substances in a given sample, since each substance absorbs a different amount of light at different wavelengths. Spectrophotometers usually have a photomultiplier tube that amplifies the signal for accurate measurement.

A spectrometer shines a light on a sample and measures how much light is absorbed at a specific wavelength.

Here is how it works: first, a bright light source is used to create light of a known wavelength and intensity. The light passes through a monochromator, which filters out all except a narrow band of wavelengths (or colors) which will be used to illuminate the sample. This narrow band of light is passed through the sample material where some is absorbed. The remaining light that passes through the sample strikes the light-sensitive detector. The detector generates an electrical signal in proportion to the light intensity. The electrical signal is amplified and read out on a meter or other device.