The helium-neon laser, commonly known as the HeNe laser, is a type of gas laser that emits a narrow and coherent beam of light in the red-orange region of the electromagnetic spectrum. This article aims to explore the characteristics of the HeNe laser, with a specific focus on its wavelength and its applications.
II. Overview of the HeNe Laser
The HeNe laser is named after the two gases it utilizes – helium (He) and neon (Ne). It operates on the principle of population inversion, which is achieved by pumping energy into the gas mixture through an electrical discharge. This process excites the electrons within the gas atoms, causing them to jump to higher energy levels. When these excited electrons return to their ground state, they emit photons in the visible spectrum.
III. Wavelength of the HeNe Laser
The wavelength of the HeNe laser is primarily determined by the energy level transition of the neon atom. The most common HeNe laser wavelength is 632.8 nanometers (nm), corresponding to a deep red color. The specific energy level transition responsible for this wavelength is known as the 3s2 to 2p4 transition within the neon atom.
IV. Factors Affecting Wavelength Stability
Several factors can influence the stability of the HeNe laser’s wavelength. Firstly, temperature changes can cause the gas mixture’s pressure to fluctuate, leading to variations in the energy level transitions and consequently the emitted wavelength. Additionally, the discharge current and voltage applied to the laser can affect the energy levels of the gas atoms, impacting the wavelength.
V. Applications of the HeNe Laser
The HeNe laser’s stable and well-defined wavelength makes it suitable for various applications. It is commonly used in the field of interferometry, where its coherent beam helps measure minute changes in distances or surfaces. Its red color also makes it useful in alignment and laser pointing devices, as it is easily visible to the human eye. Furthermore, the HeNe laser is utilized in barcode scanners, holography, and even as a reference standard in wavelength calibration.
The helium-neon (HeNe) laser possesses a distinct wavelength within the red-orange spectrum, primarily determined by the energy level transition of the neon atom. Despite potential variations resulting from factors such as temperature and discharge current, the HeNe laser’s wavelength stability remains advantageous for a wide range of applications, including interferometry, laser alignment, and barcode scanners. As technology advances, the HeNe laser continues to contribute significantly to various scientific and commercial sectors.