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Optical constants of He (Helium)
Börzsönyi et al. 2008: n 0.4–1.0 µm

Wavelength: µm
 (0.4–1)  
 

Complex refractive index (n+ik)[ i ]


n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]

$$n^2-1=\frac{4977.77\text{×}10^{-8}λ^2}{λ^2-28.54\text{×}10^{-6}}+\frac{1856.94\text{×}10^{-8}λ^2}{λ^2-7.76\text{×}10^{-3}}$$

Conditions & Spec sheet

n_is_absolute: true
wavelength_is_vacuum: true
temperature: 273 K
pressure: 100000 Pa

Comments

273 K (0 °C), 1000 mbar.
Dispersion formula may be usable down to ~0.2 µm.

References

A. Börzsönyi, Z. Heiner, M. P. Kalashnikov, A. P. Kovács, and K. Osvay, Dispersion measurement of inert gases and gas mixtures at 800 nm, Appl. Opt. 47, 4856-4863 (2008)

Data

[Expressions for n]   [CSV - comma separated]   [TXT - tab separated]   [Full database record]

INFO

Helium, He

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.

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