Jun 21 2013
Globar is a thermal light source that emits radiation near the infra red region of the electromagnetic spectrum. Globar is a thermal radiator, meaning a solid which is heated to very high temperatures to produce light radiation.
The name ‘globar’ is simply a combination of glow and bar, the heating element in the form of a bar is heated until it glows to emit radiation. Globar is a continuous radiation source that produces a broad, featureless range of wavelengths. This article will elaborate on the working, construction and applications of globars.
Working and Spectral Output
Globar is a solid light source made of silicon carbide; it is heated by resistor heating method by a current source. The silicon carbide rod is heated to temperatures of 1000 to 1650°C (1832-3002°F) and then combined with a downstream interference filter to produce radiation having wavelengths of 4 to 15 µm.
The emitted radiation from globars lies in the in the near infrared range. They are powerful sources of large amount of infrared radiation. The wavelength range of the emitted radiation is from 1 to 50 µm.
Construction
The silicon carbide rod used as the heating element of the globar rod is of length 20-50 mm and width 5-10 mm. It is in the form of a U shaped rod, where the heating element is heated by an electric current. Globars that were used in the past required a separate cooling system in order to protect the electrical components. Modern globars, however, have the cooling system inbuilt in them by using ceramic technology.
Applications
Some of the applications of globars are given below:
- Infrared spectroscopy
- FTIR (Fourier Transform Infrared Spectrometer)
- Continuous light sources for infrared microscopy
- Heating elements
Sources and Further Reading