Using He-Ne Laser in Raman Spectroscopy by Locally-Made Spectrometer.

Spectrum analysis technology using Raman spectroscopy is considered an important and common matter in the field of materials analysis in many applications. This study used the laser, which is considered one of the most important tools used in studying Raman spectrum, which is a helium-neon (He-Ne) laser with a wavelength of (632.8 nm). A locally made spectrometer with a focal length of (261 mm) connected to a CCD camera was also used in the study. The slit was used as the signal input instead of an optical Fiber, and one of its advantages is that we can manually control its width using a micrometre. Three mirrors were used, the first a flat reflective mirror, the purpose of which was to obtain the required focal length. The second mirror is spherical and is called the collimating mirror. It collects the rays reflected from the plane mirror towards the grating. The third is a toroidal mirror that has two different diameters, that is, two focal lengths, in order to reduce aberration, and it is called a focusing mirror. It focuses the rays after analysing them and projecting them onto the CCD detector. The laser appeared to have spectral lines called plasma lines. Plasma lines presented an obstacle in our work, especially the lines with high intensity compared to the Raman spectrum, which has low intensity. Raman spectra were produced for some materials and the spectrum was identical to international references.