Optical constants of He (Helium)
Cuthbertson and Cuthbertson 1936: n 0.275–0.546 µm
Complex refractive index (n+ik)
Derived optical constants
Dispersion formula
$$n-1=\frac{0.014755297}{426.29740-λ^{-2}}$$Conditions
temperature: 273.15 pressure: 101325
Comments
Standard conditions: 0 °C, 760 torr (101.325 kPa).
References
1) C. Cuthbertson and M. Cuthbertson.
The refraction and dispersion of neon and helium.
Proc. R. Soc. London A 135, 40-47 (1936)
2) C. Cuthbertson and M. Cuthbertson.
On the refraction and dispersion of neon.
Proc. R. Soc. London A 83, 149-151 (1910)
* Ref. 1 doesn't cite gas temperature and pressure. See the earlier publication by the same authors (ref. 2) instead.
Data
Additional information
About Helium
Helium (He) is a noble gas that is colorless, odorless, and tasteless. In the realm of optics, helium is frequently employed as a buffer gas in gas lasers such as helium-neon (He-Ne) and carbon dioxide (CO2) lasers. In He-Ne lasers, helium helps to excite neon atoms, thereby facilitating the laser action, while in CO2 lasers, it assists in the quick dissipation of heat. Additionally, helium's low refractive index, which is close to that of a vacuum, makes it useful in interferometry and other precision measurement techniques. Outside of optics, helium is commonly used in cryogenic environments to achieve extremely low temperatures, which are essential for certain high-precision devices like superconducting magnets used in Magnetic Resonance Imaging (MRI). Despite being one of the most abundant elements in the universe, its applications are quite diverse.
Other names and variations:- He