What is spectrometer ? what are components of spectrometer ?

Spectrometers are used to observe the spectrum of the energy transition in a sample of interest. Experimental spectrometer contains the following components,

1. Sample: The sample to be detected for spectrum is kept in the sample holder. This sample holder should be transparent to the radiation that we are going to use for the test. For example if we are using UV below 2000 angstroms air becomes opaque in that case we must use a vacuum chamber for the observation.
2. Radiation source: Radiation source is chosen according to sample we are testing. For absorption spectra in the visible and ultraviolet regions older sources were the standard types of continuous light sources: tungsten filament lamps, electric discharges and arcs, spectrum tunable lasers are also available. In emission spectroscopy, the sample is the radiation source. In this the sample is heated, by electric discharge, by radiation or by chemical reaction.
3. Optical system: The optical system is usually used to select or disperse the radiation of different wavelengths and collect it at detectors. Usually, prisms and lenses can be used as optical system. Other systems like, diffraction gratings, dispersing elements can also used.
4. Detector: This is to detect the radiation coming from the sample for intensity measurement. This is designed in such a way that it will record and display the relation between wavelength and intensity. Normally a photographic emulsion is used as a detector. In visible and ultraviolet regions, photosensitive semiconductors are used. In infrared region thermocouples and bolometers are used. In microwave region, crystal diodes are used.